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Pre Reg > Visit 2 > Flashcards

Visit 2 Flashcards

1
Q

8i

what does migraines present as

A
  • FH
  • Unilateral
  • Pulsating Pain
  • Lasts few hours – days
  • Photophobia
  • Phonophobia
  • Fatigue
  • Neck Stiffness
  • Blurred Vision
  • May have associated aura:
    o Zigzaged lines
    o Flashing Lights/Spots/Lines
    o Loss of Vision
    o Scotoma
    o Pins and Needles
  • Numbness
  • may have trigger
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2
Q

what do tension HAs present as

A
  • Bilateral
  • Pressing/Tightening
  • Mild-Moderate Intensity
  • Most common HA
  • Constant ache that affects both sides of the head – may also feel the neck muscle tighten and a feeling of pressure behind the eyes
  • Not normally severe enough to prevent you doing everyday activities
  • Can develop at any age – more common in teenagers and adults (women more than men)
  • Chronic tension-type headache
    o >15x a month for at least 3/12 in a row
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3
Q

what do cluster HAs present as

A
  • Short Lasting: 15-3hrs
  • Severe Pain
  • Unilateral
  • Neuralgiform Headache
  • Conjunctival Injection, Lacrimation or nasal congestion
  • Sweating
  • Miosis
  • Ptosis
  • Lid Oedema
    • Typically affects men in 30s or 40s
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4
Q

GCA classic presentation

A

New severe headache (maybe worse on standing up)
* Temporal artery - prominent, inflamed, non-pulsatile
* Loss of vision in one/both eyes
* scalp tenderness
* pain on jaw claudication (discomfort chewing),
* proximal myalgia (muscle pain)
* weight loss
* Malaise
* Eye pain/orbital pain (rarer symptom)

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5
Q

amaurosis fugax

A

It is a TIA
Medical Emergency!
Amaurosis fugax is a harbinger of an imminent stroke
One cause is when a blood clot or a piece of plaque blocks an artery in the eye.

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6
Q

raised Intracranial pressure presentation

A
  • Headache (diffuse, constant, aggravated by coughing/straining/bending/lying
    down, worse in morning)
  • Blurred vision - induced hyperopia
  • Transient visual obscuration of vision (postural)
  • Photopsia (perceived flashes of light)
  • Transient/persistent diplopia
  • Bilateral swelling of optic nerve head
  • Nausea and vomiting
  • Pulsatile tinnitus
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7
Q

questions to ask about diplopia

A
  • Do you have double vision such that you see two of everything?
  • Is It at distance or at near?
  • Does the double vision stop when one eye is covered? (Mono/Bino)
  • Are the double images side by side, one on top of the other or both?
  • Is the double vision always present or does it come and go?
  • Is the double vision more noticeable when looking in a certain direction?
  • Is the double vision worse when you’re tired?
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8
Q

aacg present as

A

severe temporal HA with associated pain around affected eye
nausea
vomiting
red eye

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9
Q

flashes vs migraine symptoms

A

if lights last longer than 20mins then we think possible RD
real flashes:
o Photopsia caused by vitreous traction on the peripheral retina
o Generally vertical, peripheral, more obvious in dim light, monocular

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10
Q

optic neuritis HA

A

o Fatigue, vision problems, numbness/tingling etc
o Uhthoff phenomenon: transient worsening of symptoms i.e. when core body temperature increases i.e. after exercise/hot bath
** check and add to this

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11
Q

Giant Cell Arteritis (A&E)

A
  • New severe headache (maybe worse on standing up)
  • Temporal artery - prominent, inflamed, non-pulsatile
  • Loss of vision in one/both eyes
  • scalp tenderness
  • pain on jaw claudication (discomfort chewing),
  • proximal myalgia (muscle pain)
  • weight loss
  • Malaise
  • Eye pain/orbital pain (rarer symptom)
    • Amaurosis fugax (transient blurred vision),
  • Transient diplopia
  • Cranial nerve palsies
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12
Q

Carotid Artery Dissection (A&E) presentation

Split in vessel wall -occlusion of lumen - stroke

A

Presentation
* Headache
* Gradual
* Deteriorates in severity
* Scalp tenderness
o pain in area around arm and neck.
o Ipsilateral horner’s syndrome
* characterised by:
o miosis (constriction of the pupil),
o ptosis (drooping of the upper eyelid),
o anhidrosis (absence of sweating of the face)
* Neurological signs (i.e. limb weakness, speech disturbances, visual field loss)
* Possible visual field loss (from ischaemic optic neuropathy, retinal artery
occlusion)
* Possible diplopia

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13
Q

Subarachnoid Haemorrhage (A&E) presentation

A

Presentation:
* Thunder-clap headache
o Onset = split second
o Described as: ‘worst ever headache’ the patient has experienced
Location: occipital (back of head)
Other associated symptoms:
* neck stiffness
* loss of consciousness
* agitation
* nausea
* vomiting
* Resembles acute attack of meningitis
Ocular manifestations:
* optic nerve head swelling,
* 6th nerve palsy
* Terson’s Syndrome (Haemorrhage (pre-retinal, vitreous) with a subarachnoid
haemorrhage)

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14
Q

Trigeminal Neuralgia

A

Idiopathic/secondary to compression by tumour/aneurysm/secondary to MS
* Persistent/recurrent/unilateral/periocular
* Electric shock-like quality or unpleasant ‘pins and needles’/ants crawling under
skin sensation
* Decreased corneal or facial sensation
* Anisocoria

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15
Q

health and saftey

A

o Make sure bins are not overflowing, counter tops and sink are clean – have enough tissues, paper towels and soap
o Cotton buds should be in a drawer with the lid closed over it – do not want it to be contaminated (same for NaFl strips)
o Make sure have tonometer heads and equipment in the room on the day of the assessment, looks organised and saves time
o Have a spare CL case as well for the px
o Ensure POM drops are placed in the correct bin
o Do not leave out any water bottles in the room, should be stored in a cupboard
- clean room, no hazards

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16
Q

when should MPS be discarded

A

3/12 after opening

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17
Q

for expiry dates, is it the beginning or the end of the month

A

the end of the month of jul 2024
- cannot use after july 31st

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18
Q

Fire exists in the store

A

o Front door and back door in the break room – there is also a floor layout in the break room showing the fire exits
o Certificates of the fire responders of the shop in the break room too e.g. DO and Mark
o Fire assembly point = outside M&S
o Fire extinguishers = one at the front of the shop next to the front desk and second one at the back of the shop before the staff room

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19
Q

first aid in store

A

o First aid kit in the break room
o First aiders in the shop are the directors and DO
* Would report to directors if there were any safety risks in the shop e.g. exits blocked, loose wires, tripping hazards etc.
* Hazardous substances include:
o Cleaning agents, fumes, dust, gases, bacteria and viruses

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20
Q

clinical waste

A
  • Environment Protection Act 1990 states it’s unlawful to deposit, recover or dispose of controlled waste without a waste management license and it’s the responsibility of producer of the waste to properly dispose of waste
  • Most waste produced in optometric practice is not considered clinical as it is not hazardous (known as ‘special waste’ in Scotland)
    o This means that waste such as soiled tissues and small quantities of used contact lenses can be disposed of in general domestic waste stream
    oshould have a contract with a registered waste disposal contractor, who will come to your practice to remove non-hazardous and hazardous waste when required
  • Practices should keep all waste transfer or consignment notes, and the length of time practices are required to keep these will vary depending on the type of waste
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21
Q
  • How should sharps e.g. for FB removal be disposed of?
A

in a sharps box
o Sharp boxes are colour coded according to whether they are infectious or not

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22
Q

Reusable probes (e.g. tonometer, pachymeter) should be decontaminated IMMEDIATELY by:

A
  1. Rinse with saline
  2. Wash with liquid soap
  3. Soak in sodium hypochlorite 1% for 10 minutes
  4. Rinse with saline for 10 mins
  5. Dry
    - Alcohol wipes alone do not remove prion proteins from contact devices.
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23
Q

adaptative period for rx - for child

A

18 weeks

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24
Q

what is mohindras technique?

A

done in complete darkness
use hand held lenses - WD 50cm 2D

infants <2y/o subtract 0.75 from result. Allows for 1.25D accommodation

px’s >2 y/o. Subtract 1.00D from result. Allows for 1.00D of accommodation

no cyclo needed

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25
Q

Common Risks of Developing an Anomaly of Binocular Vision

A
  • Anisometropia
  • High refractive error: >3.00 DS, >2.50DC (45% chance. If FH also, 86%)
  • Abnormal OMB
  • Positive Family History (25% chance)
  • Low Birth Weight/Premature
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26
Q

what problems does amblyopia cause

A
  • Reduced Snellen and grating acuity
    • Loss of contrast sensitivity
  • Shape distortion
  • Motion deficits
  • Crowding effect
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27
Q

why do we ask if prematurity for kids

A

o Recognised that myopia is very common in premature babies
o Premature and low birth weight babies also shown to have a higher incidence of strabismus
o Retinopathy of prematurity

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28
Q

what if child has Down’s syndrome and cerebral palsy (and other disabilities)

A
  • Less likely to emmetropise, so consider prescribing for refractive errors earlier
  • Likely to have poor accommodative response, so DO NOT reduce hypermetropic rx
    o Likely to benefit from bifocals or other styles of near rx
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29
Q

what is the ideal birth weight

A

ideally 7 pounds and 6 ounces, or 3.3kg

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30
Q

what is the expected rx type for an infant

A

o A full term neonate is hyperopic approx. +2.00 +/-2.00DS
 Pre-term can be more variable +/-2.50DS
o Infants show a high degree of astigmatism too
 Majority corneal
 Significant reduction occurs in the first year due to the increasing eye size and concurrent flattening of the cornea

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31
Q

what to ask in history for suspected strabismus

A

o Direction
o Age of which it was noticed & who noticed it
o Onset – sudden or gradual
o Constant or intermittent
o When the squint is seen
o If the angle is increased or decreased
o Other features e.g., AHP
o Defective ocular movement
o Defective vision
* Ask px about gross stereo i.e. 3D movies

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32
Q

what is amblyopia

A

A reduction is vision in one or both eyes, persistent after correction of refractive error. Absence of retinal pathology or any disease of the afferent visual pathways

Most common cause of vision loss in children , interruption of normal visual development

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33
Q

what is recorded for a latent deviation

A

direction, size, speed of recovery, changes at distances, with/without specs

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34
Q

what is recorded for a manifest deviation

A

direction, size, changes at distances, accommodation, with/without specs

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35
Q

stereopsis evident from which age

A

6 months

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36
Q

what is emmetropisation

A

 Emmetropisation: expected reduction in neonatal refractive error during normal growth
o Most active phase 12-18 months
o Can eradicate 3.00DS / 1.50DC

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37
Q

what is the active and passive stages of emmetropisation

A

o Active element = visual feedback mechanism in the control of eye growth i.e., time outdoors
o Passive element = growth of eye; decrease of corneal radius of curvature / increase in axial length

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38
Q

what is the critical period

A

 Critical period for binocular vision 0-5 years; most plastic
o Time frame in which visual deprivation results in loss of function, poor prognosis for development of binocularity and most severe visual loss

plastic = The brain’s ability to re-write both structurally and functionally in response to external influences (leaves it vulnerable to amblyopia)

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39
Q

what is the sensitive period

A

 Sensitive period 5-8 years; still vulnerable to damage and may respond to treatment

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40
Q

what are the 2 types of fusion needed for BV and stereopsis

A

motor and sensory fusion

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41
Q

what is motor fusion

A

 To put object of attention onto each fovea – maintains it there when the object moves
 Allows change of fixation from one object of attention to another
 Ensures proper alignment of both eyes
 Weak motor causes px inability to keep image single

o Interaction between this mechanism and size of deviation determines how well a phoria is compensated

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42
Q

what is sensory fusion

A
  1. Sensory fusion

o Appreciate 2 similar images and interpret as one
o How the eyes perceive and how the brain utilises

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43
Q

what innervates LR

A

6th Nerve (Abducens)

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44
Q

what inneravtes SO

A

4th Nerve (Trigeminal)

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45
Q

what innervates SR IR IO MR

A

3rd Nerve
(Oculomotor)

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46
Q

what is the action of LR

A

abduction

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47
Q

what is the action of MR

A

adduction

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48
Q

what is the action of SR

A

elevation
intorsion
adduction

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49
Q

what is the action of IR

A

depression
extorsion
adduction

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50
Q

what is the action of SO

A

intorsion
depression
abduction

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51
Q

what is the action of IO

A

extorsion
elevation
abduction

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52
Q

what is the expected vision at birth

A

6/300

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53
Q

what is the expected vision at 3 months and which test would you use?
what is the expected refraction?

A

6/90-6/60
FCPL
+3.00ds

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54
Q

what is the expected vision at 6 months and which test would you use?
what is the expected refraction?
expected stereo?

A

6/36-6/60
keeler FCPL
+2.50DS
stereo 600

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55
Q

what is the expected vision at 1 yr and which test would you use?
what is the expected refraction?
expected stereo?

A

6/18
cardiff acuity cards
+2.00DS
210-170 stereo

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56
Q

what is the expected vision at 2 yrs and which test would you use?
what is the expected refraction?
expected stereo?

A

6/12-6/9
cardiff/kays pictures/ sheridan gardiner
+1.25DS
100-85 stereo

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57
Q

what is the expected vision at 4 yrs and which test would you use?
what is the expected refraction?
expected stereo?

A

6/9 -6/6
snellen
+0.50DS
40-30 stereo

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58
Q

normal BSV: whats panums area and horopter

A

 Horopter: all images constant size, viewed as single
 Panums fusional area: images here as viewed in 3D; images outside space cause large disparities that cannot be fused i.e., physiological diplopia

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59
Q

for amblyopia - how often should a px be reviewed

A

 Patient should be reviewed regularly, minimum every 3 months
 Age in years = review in weeks (4 years old = 4-week reviews)
 VA stable 2 consecutive visits = consider tapering off/stopping occlusion
 Amblyopia persist & px compliant = refraction & fundus check, increase occlusion to FT or change therapy
 Amblyopia persist & px non-complaint = instruction leaflet, reward scheme, video game therapy, change regime

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60
Q

muscle sequlae

A
  1. Under action of the primary affected muscle
  2. Overaction of the contralateral synergist – Hering’s Law
  3. Overaction of the ipsilateral antagonist – Sherrington’s Law
  4. Inhibition palsy of the contralateral antagonist
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61
Q

what is abnoraml retinal correspondence

A

describes a condition in which originally non-corresponding retinal areas of the two eyes co-operate to produce a form of binocular single vision - never as good as having normal

A shift in the spatial localisation of the deviating eye occurs to counteract the effect of the ocular deviation

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62
Q

what is suppresion

A

 Cortical mechanism; mental inhibition of visual sensations in one eye in favour of the other
 Develops rapidly in childhood; more slowly in older children up to 10years
 Suppression should only be treated if the deviation can be eliminated and strong chance of restoring BSV
 Physiological = normal
 Pathological = used to overcome binocular diplopia in manifest strabismus or incompatible images due to significant degree of anisometropia – central suppression develops in poorer eye

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63
Q

what is normal retinal correspondance

A

both foveae have common visual directions - produce a single image

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64
Q

what is an incomitant devation and what is concomitant deviation

A

Comitant strabismus
The angle of eye deviation remains the same regardless of the direction of gaze. This is the most common type of strabismus in children.

Incomitant strabismus
The angle of eye deviation changes depending on the direction of gaze. This type of strabismus is often caused by limited eye movement due to neurological, mechanical, or myogenic issues.

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65
Q

what size is a small/med/large deviation?

A

 Any deviation <4 prism D cannot be seen
 Small – 4-8D
 Moderate – 8-16D
 Large - >16D

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66
Q

what is fixation disparity

A

measures the amount of uncorrected phoria, measured with rx
done on anyone who can accommodate
due to panums area the eyes can be misaligned during binocular viewing w/o diplopia,

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67
Q

what causes an individual to get an hetereophoria

A

anatomical causes, refractive causes, uniocular activity and trauma

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68
Q

what happens when an heterephoria decompensates

A

o In compensated heterophoria, motor fusion is maintained, therefore sensory fusion and stereopsis should occur
o If phoria is large or fusional reserves small – increasing degrees of decompensation of the heterophoria can occur with increase in symptoms i.e., asthenopia, headaches, intermittent diplopia
o As decompensation professes, fusion may break down completely – resulting in a manifest deviation & inevitable double vision

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69
Q

Concomitant deviations in adults require management if:

A
  1. Cosmetically unacceptable / patient would like surgery to improve alignment (surgery usually when angle >20^)
  2. Strabismus has become symptomatic producing diplopia - may occur if a change to the angle of deviation causes the image to fall outside the suppression scotoma
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70
Q

what causes someone to get an heteroptropia

A

o Anomalies in development of skull or orbital structures
o Other non-structural conditions i.e., cerebral palsy
o Any impediment to good vision (i.e., congenital cataract) is an impediment to sensory and therefore motor fusion
o Downs syndrome

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71
Q

muscle balance test, eg maddox rod, what does it do

A

measure the full extent of the phoria, useful for small deviations, especially vertical, not suitable for accommodative deviations
XOP - images crossed, base in prisms needed
SOP - images uncrossed, base out prisms needed
*cannot use maddox rod to prescribe prism

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72
Q

how and why are fusional reserves measured

A

when phoria is not controlled then phoria is decompensated
base out - positive fusional reserves, corrects SOP
base in - negative fusional reserves, corrects XOP

*distance correction and lights on
done on any eye
infront of px, at distance and near, target single letter, a line bigger than VA for poorer eye
blur break recovery

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73
Q

symptoms of decompensated heterophoria

A

frontal HA’s, asthenopia, intermittent diplopia, Photophobia, Difficulty changing focus from near to distance and vice versa, Blurring of reading, Crowding of words while reading

o As decompensation professes, fusion may break down completely – resulting in a manifest deviation & inevitable double vision
o Frontal headaches & asthenopia = caused by EFFORT to maintain BSV (tend to occur later on in the day)
o Transitory diplopia & blurred vision = caused by FAILURE to maintain BSV (noticed more when tired or unwell)

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74
Q

what can cause decompenstated phorias

A
  • Optical causes: uncorrected/under corrected refractive errors (eso = hyperopia, exo = myopia), wrong corrected refractive errors by reducing VA and dissociating the eyes, ill-fitting specs causing prismatic effect, aniseikonia
    o SOP in younger age groups
    o XOP in elderly age groups
    o Convergences excess SOT
    o Accommodation excess SOT
    o Ill-fitting specs – induced prismatic effect
    o Uncorrected spherical errors
    o Medical causes e.g. poor GH, head trauma, meds, alcohol, stress
    o Precision jobs
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75
Q

management of decompensated phorias

A

o Full correction first line of management
 SOP decompensated by uncorrected hypermetropia – acts as BO
 XOP decompensated by uncorrected myopia – acts as BI
o Ill-fitting specs can results in a prismatic effect if the lenses are decentred and can increase the degree of phoria and make control more difficult
o Orthoptic exercises for divergent/convergent insufficiencies
 Decompensated XOP are easiest to treat with exercises
o 20-20-20 for prolonged near work
o Bifocals to relax accommodation
o Prisms in elderly pxs (usually first choice)
o Botox injections if prism does not work

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76
Q

how to use maddox rod

A

o Room lights off
o Maddox rod place in front of the non-fixing eye with the cylinder axes horizontal
o Px fixates the spotlight with the other eye and is asked on which side they see the vertical red line
o Prism is held in front of the rod with its base orientated in the direction of the line and the strength of the prism is adjusted until the line passes through the light
o Repeated with the other eye and then to correct any vertical deviation
o Line is seen in the opposite direction of the deviation
 HYPER – line is seen below dot
 HYPO – line is seen above dot
 RE ESO – line is seen temporally/right
 RE EXO – line is seen nasally/left

  • Double Maddox rod
    o Used to assess cyclotorsion
    o 2 lines are seen – red and white – and ideally they should be parallel if no deviation is present
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77
Q

meaning of pinhole results

A

o No improvement – indicates pathology
o Improvement – issue with rx
o Worse with pinhole – macular problem

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78
Q

principle of duochrome

A

based on the principle of longitudnal chromatic aberration, whereby short wavelength light (green) is refracted more than the light of longer wavelengths (red)

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79
Q

why do we do +1.00 blur test?

A

very useful for refracting young children with very active accommodation, but is useful in any pre presbyopic px’s to make sure you have not given too much minus or plus

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80
Q

why do we want duochrome to be on green for cross cyl

A

green duochrome to ensure circle of least confusion is on the retina

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81
Q

what is the vitreous

A

 The vitreous is a clear gel which fills the vitreous cavity and occupies about 80% of the volume of the globe
 The vitreous consists of mostly water, as well as hyaluronic acid and a meshwork of collagen fibres

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82
Q

attachments of the vitreous

A

o Vitreous base/ora-seratta
o Posterior lens capsule
o Optic disc
o Macula
o Along the retinal vessels

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83
Q

Where is the strongest attachment of the vitreous

A

Vitreous base is the strongest attachment. The vitreous base is a 3-4mm wide zone of vitreous which straddles the ora seratta. At the vitreous base, the collagen fibres at attached to the underlying peripheral retina.

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84
Q

what do the posterior and anterior hyaloid membrane do

A

 Posterior hyaloid membrane separates rear of vitreous from retina
 Anterior hyaloid membrane separates front of vitreous from lens

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85
Q

what is the ora seratta

A

junction between the ciliary body at the retina

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86
Q

how to examine anterior vitreous

A

o Bright, thin slit beam focused on anterior vitreous (posterior lens and slightly forward)
o Volk lens is not used for this
o Ask patient to look up-down-straight ahead
o Pigmented cells in anterior vitreous = tobacco dust = +VE shafers
o Helps exclude break – only 8% eyes with breaks and shafers negative

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87
Q

what is a PVD

A

 PVD occurs when the posterior vitreous separates from the retina and collapses anteriorly towards the vitreous base
 This occurs due to vitreous syneresis (with age) in which the vitreous becomes more-fluid like
 An opening can the develops in the posterior vitreous through which liquefied vitreous passes through causing the posterior hyaloid membrane to pull away from the retina
 Spontaneous PVD is common but may also follow surgery, trauma, uveitis or laser
 It may cause troublesome floaters or retinal tears which may lead to a detachment

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88
Q

why do floaters occur

A

o Caused by vitreous opacities such as glial tissue from the disc, condensations of collagen fibres or blood
o Shadows are cast on the retina and seen as floaters

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89
Q

management of PVD

A

 PVDs are non-sight threatening and symptoms usually reside after 1-3 months
 Explaining & reassuring patient
 Advise px tor return if any sudden change or worsening of flashes/floaters or any visual field defect – provide a patient advice leaflet
 Within 6/52 from initial symptoms – PVD has greater risk of developing into RD
 Review in 6/52 from initial symptoms to ensure no RD has occurred
 Very occasionally, extremely symptomatic patients may require a vitrectomy

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90
Q

what is lattice degeneration

A

 Retinal thinning associated with overlying vitreous liquefaction / abnormally strong vitreoretinal adhesion
 Stress caused by vitreous is worse in these areas, so retina is more likely to tear here
 Spindle shaped areas of retinal thinning; sclerosed vessels forming network of white lines
 Routine prophylaxis is not justified

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91
Q

signs of RD

A

*IOP often lower by about 5mmHg
* RAPD
* +VE Shafers – tobacco dust/pigmented particles in anterior vitreous

*Chronic detachments often have thinned retina, RPE pigmentation at the border of detached retina (high-water mark)
Record:
o Extent of RD
o Any macular involvement
o Any breaks/lattice degeneration

  • Pigment in the fundus – Demarcation line
  • operculum in vitreous
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92
Q

what is a retinoschisis

A

 Benign, idiopathic, splitting of the neurosensory retina at the level of the OPL
 Relatively common – 5% population
 More common in hyperopia
 Non-progressive/not sight-threatening

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93
Q

retinoschisis signs and symptoms

A

 Usually no symptoms
 OCT useful – has the whole retina detached as in a retinal detachment or is it just a slitting of the neurosensory retina?
 No retinal break
 More common inferior temporal/peripheral area – loss of visual function in this area but it is peripheral and rarely noticed
 Bilateral
 Dome-shaped elevation

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94
Q

Differential diagnosis of retinal detachments

A

 PVD
 Choroidal mass – urgent referral
 Retinoschisis – no referral needed/observation in community practice

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95
Q

what is a retinal detachment

A
  • Refers to the separation of the neurosensory retina (NSR) from the RPE
  • This results in the accumulation of sub-retinal fluid (SRF) in the potential space between the NSR and RPE
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96
Q

what causes vitreomacular traction

A

caused by the vitreous gel in the eye remaining attached to the macula after a posterior vitreous detachment

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97
Q

what is the purpose of binocular balance

A

goal of equalising accommodative effort in the 2 eyes and achieving the bet possible binocular refraction

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98
Q

risk factors for PVD

A

 Increased age, common in 50+
 Axial length – myopic eyes more at risk (experienced 10 yrs earlier)
 Following surgery i.e. cataract
 Trauma

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99
Q

what is a horseshoe tear

A

 Starts with PVD, typically in older patients
 Persistent vitreous traction and increasing SRF
 50% result in detachments – emergency referral for prophylactic Tx
 Rapidly progressive
 Laser Tx is likely

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100
Q

giant tear

A

 Starts with PVD, typically in older patients
 Large break, high risk of complications, worst prognosis

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101
Q

atrophic hole

A

 No PVD; typically, in young (myopic patients)
 Tide mark appearance
 Most likely to be asymptomatic

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102
Q

diaylsis RD

A

 No PVD; typically, in younger px’s
 Detachment may be large, usually infero-temporal
 May be due to trauma

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103
Q

tractional RD most common cause

A

 Mainly caused by fibrosis from severe diabetic retinopathy

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104
Q

does tractional RD cause symptoms

A

Flashes/floaters usually absent because vitreoretinal traction develops insidiously, and is not associated with PVD

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105
Q

signs of tractional RD

A

 Concave configuration, breaks absent
 Retinal mobility reduced, shifting fluid absent
 Highest elevation of retina occurs at sites if traction
 If develops a break – assumes characteristics of RRD

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106
Q

what is an exudative RD

A

 No breaks with shifting sub-retinal fluid
 May occur due to a variety of vascular, inflammatory and neoplastic diseases
 Involves the retina, RPE and choroid in which fluid leaks and accumulates under retina

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107
Q

symptoms of exudative RD

A

No flashes, floaters if Vitritis, field defect may develop & progress rapidly

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108
Q

signs of exudative RD

A

 Convex configuration, but smooth surface
 Detached retina is mobile, shifts fluid
 Leopard spots consisting of scattered areas of subretinal pigmented clumping may be seen after detachment has flattened

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109
Q

management for a RD

A
  • Pneumatic retinopexy – gas bubble inserted in eye
  • Cryotherapy or laser retinopexy to create an adhesive scar; prevents vitreous fluid moving into subretinal space
  • Scleral buckle
  • vitrectomy

o Remove gel & remove traction on retina
o Ensure retina is back in place using cryotherapy or laser, to reattach retina to RPE
o Takes some time, usually put air (lasts 1 week)/gas (short acting 2 weeks, long acting 5-8 weeks)/oil (complex detachments; can see and fly, hyperopic shift but 2nd operation to remove) to allow it time to stick properly
o In this time, patient cannot see or fly
o Overtime, bubble gets smaller, rounder and lower over period of time

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110
Q

what is white without pressure

A

Areas of peripheral whitening on the retina seen
without scleral indentation. Caused by a changes in the vitreoretinal attachments
which result in retinal atrophy and abnormal vitreo-retinal adhesion

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111
Q

when would you do an emergency referral for RD

A
  • RD with good VA (Macula On),
  • Vitreous or pre-retinal haemorrhage,
  • Pigment in anterior vitreous,
  • Retinal Tear/Holes with symptoms
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112
Q

when would you do an urgent referral for RD

A
  • RD with poor VA (Macula off) unless this is longstanding retinal hole/tear without
    symptoms.
  • Lattice degeneration with symptom of flashes and floaters
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113
Q

risk factors for RD

A

o chances are higher in myopes
o Px with FH of retinal detachment
o RD in other eye
o Post complicated cataract surgery – with vitreous loss
o Injury to eye
o YAG laser capsulotomy in high risk eye (high myopes)

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114
Q

what is snail track degeneration

A

o Characterised by sharply demarcated bands of tightly patched ‘snowflakes’ that give the peripheral retina a white frost-like appearance

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115
Q

what is Cystic retinal tuft

A

o Congenital abnormality
o Small, round or oval, discrete elevated whitish lesion
o Typically in the equatorial or peripheral retina
o There may be associated pigmentation at its base

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116
Q

what is Zonular traction tuft

A

Common phenomenon caused by an aberrant zonular fibre extending posteriorly to be attached to the retina near the ora serrata, and exerts traction on the retina at its base

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117
Q

what is white with pressure

A

o Refers to retinal areas in which a translucent white-grey appearance can be seen by scleral indentation
o Frequently seen in normal eyes and may be associated with abnormally strong attachment of the vitreous gel, though may not indicate a higher risk of retinal break

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118
Q

what is myopic chorodial atrophy

A

o Diffuse or circumscribed choroidal depigmentation, commonly associated with thinning of the overlying retina
o Retinal holes developing in the atrophic retina may occasionally lead to RD

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119
Q

what is wet AMD

A

abnormal growth of BV

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120
Q

what is dry AMD

A

 DRY AMD = retinal cells die off & are not renewed (because function of RPE is reduced)
o Geographic atrophy = cell death of RPE cells

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121
Q

what is normal (for AMD)

A

o No signs of AMD
o Small (hard) drusen <63 microns)

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122
Q

what is Early AMD with low risk of progression

A

o Medium drusen 63-125 microns
o Pigmentary abnormalities

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123
Q

what is Early AMD with medium risk of progression

A

o Large drusen >125microns
o Reticular drusen
o Medium drusen with pigmentary abnormalities

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124
Q

what is Early AMD with high risk of progression

A

o Large drusen with pigmentary abnormalities
o Reticular drusen with pigmentary abnormalities
o Vitelliform lesion with significant visual loss (BVA <6/18)
o Atrophy smaller than 175 microns and not involving fovea

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125
Q

what is late AMD

A

o Geographical atrophy
o Significant visual loss associated with
 dense/confluent drusen
 advanced pigmentary changes and/or atrophy
 vitelliform lesion

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126
Q

what is seen in late AMD (wet inactive)

A

o Fibrous scar
o Sub-fovea; atrophy or fibrosis secondary to an RPE tear
o Atrophy
o Cystic degeneration
o Eyes still may develop of have recurrence of late wet active AMD

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127
Q

what is seen in late AMD (wet active)

A

o CNV
o Ocular (fibrovascular PED / serous PED with neovascularisation
o Mixed predominantly or minimally classic CNV with occult CNV)
o Retinal angiomatous proliferation (RAP)
o Polypoidal choroidal vasculopathy (PCV); macular neovasc, occurs more in African Americans & Asians

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128
Q

what is seen in late AMD (indeterminate)

A

o RPE degeneration and dysfunction
o Serious PED without neovascularisation

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129
Q

prevalence of AMD

A

 Generally over 55 years old
 AMD leading cause of VI
 Accounts for over 5-% of those registered SI or SSI
 4.8% over 60s
 65-74 = 11%
 12.2% over 80s
 75-85 = 28%
 Estimation: 670,000 people in UK = late AMD

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130
Q

Risk Factors of AMD

A
  • Age ^
  • Race - late AMD more common in Caucasians
  • Gender – females > males
    o Greater risk possibly due to longevity
  • Heredity – risk of AMD is up to 3 times as high if first-degree relative has the disease
  • Smoking - doubles risk (2-3x) of AMD
    o Tar of cigarettes = hydroquinine = oxidative stress = DRY
    o Nicotine = induces capillary formation = WET
  • Hypertension & other cardio-vascular risk factors (vascular disease > ischaemia/accumulation of waste products > degeneration of RPE)
  • Dietary factors
    o Low in omega 3 & 6, vitamins, carotenoids, and minerals
    o High fat intake, obesity, excessive alcohol consumption
    o BMI of 30 = higher risk
  • Aspirin – evidence is limited
  • Females – greater risk possibly due to longevity
  • Cataract surgery – can speed up progression from dry to wet
  • No evidence for increased risk of AMD due to light exposure
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131
Q

symptoms of dry AMD

A

gradual reduction (over months-yrs)
bilateral changes
distortion only in advanced cases

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132
Q

symptoms of wet AMD

A

loss of vision more quickly
unilateral/ one eye worse
severe/ obvious distortion noticed

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133
Q

which layer is affected in dry AMD

A

sub rpe

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134
Q

which layer is affected in wet AMD

A

subretinal layer

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135
Q

signs of dry AMD

A

drusen (hard or soft)
pigmentary changes
eventual development of geographic atrophy

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136
Q

signs of wet AMD

A

med - large drusen
subretinal or preretinal haemorrhage
CNV
PED
CMO

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137
Q

what is CNV

A

Consists of a blood vessel complex that extends through Bruch membrane from the choriocapillaris into the sub-RPE (type 1) or subretinal (type 2) space
* May be identifiable as a grey-green or pinkish-yellow lesion
o Associated medium-large drusen are a typical finding in the same or fellow eye
o Sometimes CMO

138
Q

dry AMD tx

A
  • Px may register as sight impaired – need referred to ophthalmologist to complete this form
  • Px may access low vision services and LVAs
    o Hand/stand magnifiers (illuminated vs non-illuminated options)
    o Typoscope
    o Use large prints/increase text size on phone
    o Black felt tip pens to see writing easier
    o Audio books and Kindles (reduce glare and can increase contrast)
    o Alexa/Google home – allows px to speak to device and it can call friends/family, tell the time/news etc.
    o Liquid level indicators, talking microwave, phone with bigger numbers etc.
  • Training
    o Eccentric viewing
    o Steady eye strategy
  • Useful websites e.g. Macular Society, RNIB, Citizens Advise, Sightline
  • May have to refer to the GP for psychological problems that arise e.g. depression
  • Stop smoking
  • Eat healthier, exercise, diet rich in green leafy veg and fruit – no firm evidence but no harm in doing so
  • Protect eyes from sunlight – tinted (absorptive) lenses
    o May suffer discomfort from glare
139
Q

Dry AMD supplements

A

AREDS study 2 contain lutein and zeaxanthin
#AREDS2 formula also reduced the risk of lung cancer compared to the original formula, which contained beta-carotene
AREDS2 supplements help slow the progression from intermediate to late AMD.

140
Q

WET AMD referral

A

Urgent referral (within week) if suspect AMD – done via Fast-track Wet AMD referral (through SCI gateway)
There must be a recent history (usually < 3/12) of at least one of the following
* Visual loss (VA 6/12 or worse)
* Spontaneously reported distortion
* Onset of missing patch/blurring of central vision
* NB corrected VA must be 6/96 or better in the affected eye – if any worse than this may be no improvement with injections

141
Q

Side effects of anti vegf

A

 Side effects include bleeding in the eye, feeling as if there is something in the eye, eyes being red and irritated

142
Q

o Photodynamic therapy (PDT) for AMD

A

 Light is shone at the back of the eye to destroy the abnormal BVS that cause wet AMD
 May be recommended alongside eye injections if they don’t help alone
 Usually needs to be repeated every few months
 Side effects include temporary vision loss, and the eyes and skin being sensitive to light for a few days/weeks

143
Q

anti VEGF drug used and process

A

 Most used treatment
 Criteria – 6/12 or worse
 Avoids the proliferation of new & unhealthy blood vessels
 Visual prognosis
o 25% cases VA improves
o 90% VA remains stable
 Ranibizumab (lucentis) – approved by NHS Scotland & NICE - £742
o Initial loading dose – 3 injections, every 4 weeks
o Maintenance injections usually 1-3 months, for as long as necessary
o Effective for all lesion types
 New drug – Brolucizumab (Beovu) – now approved by NHS Scotland & NCE, can increase time between appointments to 12 weeks – minimize treatment burden for patients

144
Q

contraindications for advising AMD supplements

A

o Smoking & Beta carotene – More likely to trigger lung failure
o Genitourinary problems & Zinc - May cause kidney stones or UTI
o Heart failure & Vitamin E – Increased risk of heart failure
* Ensure the patient speaks to a doctor/pharmacist about the supplements
BEFORE they are taken

145
Q

macular hole

A

is a retinal break that involves the fovea, most macular holes are idiopathic
however it could also be due to traction between the posterior hyaloid membrane and parafovea and this occur as
complication of a posterior vitreous detachment (PVD)
URGENT REFERRAL (within one week) - vitrectomy usually
Symptoms Metamorphopsia (distortion of central vision), central vision loss or scotoma

146
Q

when would you refer a sub conjunctival haemorrhage

A

B3: management to resolution
Refer to GP if suspicion of hypertension or bleeding disorder, or if condition is recurrent

A1: if orbital fracture or intracranial source of haemorrhage suspected, emergency (same day) referral
to A&E

147
Q

what to ask about for sub conj haems

A

hypertension, medications, acute or chronic cough, eye rubbing, heavy lifting, recent ocular or head trauma, bleeding or clotting abnormalities and recurrent subconjunctival haemorrhage

148
Q

differential diagnosis of sub conj haemorrhage

A

Acute haemorrhagic conjunctivitis (AHC)

viral conjunctivitis (typically enterovirus; usually small multiple haemorrhages; rare)
usually bilateral
Retrobulbar haemorrhage

Conjunctival neoplasms (e.g. lymphoma) with secondary haemorrhage

Kaposi’s sarcoma (red or purple lesions under conjunctiva)

149
Q

what is the difference between pedunculated and sessile papillomas

A

Pedunculated papillomas are more elevated and have a rough surface, while sessile papillomas are broad based and slightly elevated with a smooth surface. Pedunculated papillomas can look like a skin tag attached to the eyelid by a stalk

150
Q

general management for sub conj haem

A
  • Measure BP
  • ensure posterior borders visible to rule out intra-cranial source
  • If recurrent refer to GP
  • Reassure px
  • Advise condition clears within 5-10 days and return if no resolution
151
Q

differential of ptergium

A

o Pinguecula (no corneal involvement)
o Pannus: an immune system condition that occurs as a result of ultraviolet (UV)
light damage to the side of the cornea – the clear part of the eye – that triggers
the body to attempt to repair the damage by sending small blood vessels into the
layers of the cornea

152
Q

what is pterygium

A

Benign wing shaped fold of fibrovascular tissue
Degenerative condition usually found in Hot/High UV climates

153
Q

management of pterygium

A
  • UV protection (reduce risk of progression)
  • photo document
  • cold compress when inflamed
  • Ocular Lubricants

Refer for Surgical Excision if:
o threatens visual axis
o induces irregular astigmatism
o is associated with chronic inflammation
o is cosmetically unacceptable.

154
Q

cause of pinguecula

A

Yellow/White deposit on the bulbar conjunctiva
due to degeneration of the collagen fibres in the conjunctival stroma, thinning of the
overlying epithelium and occasional calcification

155
Q

signs of bacterial conjunctivitis

A
  • Lid crusting
  • Purulent discharge
  • Conjunctival Hyperaemia
  • Papillary Reaction
  • no corneal involvement usually à if corneal, possibily gonococcal
156
Q

management of bacterial conjunctivitis

A
  • Often resolves in 5-7 days without treatment,
  • Bathe and clean the eyelids
  • Advise px it is contagious
  • Treatment with topical antibiotic (chloramphenicol, fusidic acid)
  • Cease any lens wear.
  • Return if symptoms persist past 7 days.
  • Manage to resolution
  • Refer – If condition persists or if there is corneal involvement
157
Q

Contact lens wearers with a diagnosis of bacterial conjunctivitis should be treated with

A

topical antibiotic effective against Gram –ve organisms, such as an aminoglycoside (e.g. gentamycin) or a quinolone (e.g. levofloxacin or moxifloxacin)
no cls worn in this time

158
Q

when would bacterial conjunctivitis be referred

A

B3: management to resolution. Refer if condition fails to resolve, or if there is corneal involvement.

A3: If condition fails to resolve, or if there is corneal involvement, urgent referral (within one week) to ophthalmologist

159
Q

viral conjunctivits signs

A
  • Watery discharge
  • Conjunctival hyperaemia (may be intense),
  • Follicles on palpebral conjunctiva (upper and lower fornix),
  • Subconjunctival haemorrhages,
  • Corneal involvement in some cases
  • punctate epithelial lesions initially progressing to sub epithelial lesions which may
    persist for months.
  • Pseudo-membrane on tarsal conjunctiva (Severe)

Px usually have had a cold or other upper respiratory tract infection

160
Q

viral conj management

A
  • Advise highly contagious
  • Self-limiting resolving in 1-2 weeks
  • cold compress
  • cease lens wear
  • monitor for corneal involvement or development of pseudo-membrane.
  • Ocular lubricants
  • Refer – If Corneal involvement (keratitis – severe pain / visual loss) or pseudomembranes on conjunctiva (EMERGENCY)
161
Q

what is disciform keratitis

A

central or eccentric zone of epithelial oedema overlying stromal thickening
folds in Descemet’s membrane
uveitis
Keratic Precipitates

162
Q

sings of angle closure glaucoma

A

Unilateral,
* Elevated IOP,
* Hyperaemia,
* Corneal epithelial and/or stromal oedema,
* Descemet’s folds,
* Shallow or flat AC,
* Mid dilated pupil with absent reactivity,
* conjunctival congestion

163
Q

HZO more likely in who

A

HZO is when the nasociliary branch of the ophthalmic division of the trigeminal nerve is
involved.
It generally occurs between 60-70 however can occur at any age especially in
immunocompromised patients

Most people get infected with the virus varicella (chicken pox) and the virus lays
dormant. However, a reactivation will lead to zoster (shingles)

164
Q

signs and symptoms of HZO

A

general

  • unilateral painful red vesicular rash on the forehead and upper eyelid progressing to crusting after 2- 3 weeks
  • resolution often involves scarring.
  • Periorbital oedema
  • lesion at side of tip of the nose (Hutchinson’s sign)
  • mucopurulent conjunctivitis associated with vesicles on lid margin
  • scleritis
  • Episcleritis
  • Keratitis (punctate epithelial, pseudodendrites, nummular, disciform, reduced sensation, endothelial changes and KP)
  • anterior uveitis
  • glaucoma
  • posterior uveitis
  • optic neuritis
  • optic atrophy
    Neurological
  • CN palsy
  • optic neuritis
  • encephalitis
  • post herpetic neuralgia

fever, malaise, HA, pain and altered sensation of the forehead on one side

165
Q

HZK management

A

Co-management with GP if keratitis limited to epithelium.
* URGENT (within one week) if deeper corneal involvement such as a disciform
keratitis or neurotrophic ulcer.
* EMERGENCY REFERRAL TO GP for acute skin lesion

166
Q

HSK management

A

(acute or recurrent epithelial HSK with no stromal involvement): alleviation or palliation; monitor closely within first 72 hours to evaluate healing, but refer urgently (within one week) to ophthalmologist if epithelium has not healed after seven days
A1 (if stroma involved, or in children or contact lens wearers, or in bilateral cases): emergency (same day) referral to ophthalmologist

167
Q

HSK signs and symptoms

A

Unilateral (may be bilateral)
* Pain
* Burning
* Photophobia,
* Reduced VA
* Redness

Epithelial :
* Punctate lesion coalescing into dendriform pattern
* dendritic ulcer
* Opaque cells arranged in stellate pattern progressing to liner branching ulcer associated with decreased corneal sensitivity
* Geographic ulcer in late stage

Stromal:
* Necrotic stroma
* stromal infiltrates
* vascularization
* scarring
* keratic precipitates
AC
* uveitis and raised IOP

168
Q

anterior uveitis signs

A
  • Circumlimbal injection,
  • AC flare and cells,
  • Keratic Precipitates,
  • Pupil Miosis,
  • Hypopyon,
  • Band Keratopathy,
  • Fibrin in the AC,
  • Cells in anterior vitreous,
  • Peripheral anterior synechiae (PAS),
  • Posterior Synechiae,
  • Rubeosis Iridis,
  • Mutton fat KP,
  • Iris nodules.

IOP – Reduced (Aqueous humour production reduced),
Normal/Elevated IOP (Inflammation affect outflow pathway)

169
Q

severity of anterior uveitis grading

A
  • Mild – VA 6/6 -6/9, Superficial circumcorneal flush, No KPs, Grade 0 -1+, Normal
    pupil, no posterior synechiae, no iris swelling, IOP reduced <4mmHg.
  • Moderate – VA 6/9 – 6/30, Deep circumcorneal flush, KPs, Grade 1+- 3+, Miotic or
    sluggish pupil, Mild posterior synechiae, Mild iris swelling, IOP reduced 3-6 mmHg,
    Anterior vitreous cells.
  • Severe – VA<6/30, Deep circumcorneal flush, KPs, Grade 3+-4+, sluggish or fixed
    pupil, Fibrous posterior synechiae, Iris crypts, IOP increased, Moderate to Severe
    anterior vitreous cells.
170
Q

grading of cells and flare

A
  • Grade 0 - No Flare / No Cells
  • Grade 1+ -Faint Flare (Barely detectable)/5-10 Cells in view
  • Grade 2+ - Moderate Flare (Iris and Lens still clear) / 10 - 20 Cells in view
  • Grade 3+ - Marked Flare (Iris and Lens Hazy) / 20 – 50 Cells in view
  • Grade 4+ - Intense flare (coagulated aqueous, fibrin visible) / 50+ Cells in view
171
Q

what causes cataract

A

Caused by denaturation of protein fibrils within the lens due to oxidative
stress, increasing age and metabolic disturbance

172
Q

NS risk factors and signs

A
  • Poorer Diet
  • Low socio-economic status
  • Age
  • Smoking
  • Larger Lens
  • Higher Ambient Temperature
    Signs:
  • Yellowish hue
  • Myopic Shift
173
Q

cortical risk factors and signss

A

Cortical – Appearance of spokes
* Sunlight (UVB)
* Lens size
* Age
* Diabetes
* Smoking
* Female
* Non-Caucasian
Signs:
* Increased astigmatism
* Monocular Diplopia

174
Q

posterior sub cap risk factors and signs

A

Posterior Sub-capsular – abnormal epithelial cells and granular material at posterior pole
due to swelling and breakdown of lens fibres
* Diabetes
* High Myopia
* Steroids
* Age
* Male
* Thyroid Hormone Use
Signs:
Rapidly progressing loss of visual acuity.

175
Q

what happens in cataract surgery

A
  1. Day case procedure
  2. Local anaesthetic drops and possibly intra-cameral (into AC) injection
  3. Small incisions made in the cornea (1-3mm in size)
  4. Viscoelastic substance injected to maintain shape and pressure in eye
  5. Capsulorrhexis – round incision made in the anterior capsular bag to get
    access to the cataract
  6. Hydrodissection – fluid injected between the capsule and cataract to
    separate them
  7. Phacoemulsification - high frequency ultrasound device which breaks the
    cataract up into 2-4 small pieces which are then suctioned out
  8. A folded artificial intraocular lens (IOL) is then inserted (via the small
    incision) and placed into the capsular bag
  9. Stitches are rarely required due to it being keyhole surgery
176
Q

cataract surgery risks - said to px

A

1 in 10,000 - loss of eye
1 in 1000 endophthalmitis (a very serious complication)
1 in 100 will have a more serious complication resulting in a poor outcome
1 in 300 persistent corneal oedema
1 in 50 cystoid macular oedema
95% of patients have a straightforward operation

177
Q

complications 48 hrs post catarct surgery

A

Corneal oedema
o Raised IOP
o Uveitis
o Cystoid macular oedema
o Periocular Bruising,
o Wound leak,
o Wound burn,
o Hyphaema

178
Q

what is the drainage system

A

Drainage – through the puncta, through canaliculi, into lacrimal sac to the nose. Pumped into there
from lid action and gravity feed to lower punctum

179
Q

what is dry eye disease

A

A disorder of the tear film due to tear deficiency or excessive evaporation, which causes
damage to the interpalpebral ocular surface and is associated with symptoms of ocular
discomfort.

180
Q

what are the layers of the tear film?

A
  • lipid layer
  • aqueous layer
    -mucus layer
181
Q

what is the role of the lipid layer?

A

Reduces water evaporation from the aqueous layer
Secreted by: Meibomian gland, glands of Zeiss, glands of Moll.

182
Q

what is the role of the aqueous layer

A

carries nutrients and oxygen to the eye and
carries away waste. Hydrates the cornea and prevents it from
drying out.
Secreted by: Main lacrimal gland for reflex secretion, Basal
secretion by accessory lacrimal glands of Krause and Wolfring

183
Q

what is the mucus layer role

A

Trap debris and epithelial cells, which are then removed through blinking. Also allows for tear stability and adheres
to the epithelial corneal cells and conjunctival goblet cells

184
Q

normal value for schirmers test

A

o 35mm x 5mm strip of paper is inserted into the temporal side of the eyelid
o Assess tear production
o A normal tear film should produce a wetting length of > 15mm in 5 mins

185
Q

what is the Phenol thread test

A

o Less invasive than Schirmer
o Phenol red is pH sensitive and changes from yellow to red when wetted by tears, due to the alkaline nature of tears (pH 7.4)
o Thread is placed in the eye for 15s – colour of thread is then measured
o Wetting lengths should normally be between 9mm and 20mm, values less than this have been shown to correlate with subjective symptoms of dryness

186
Q

tear meniscus height

A

o G1: >0.3mm
o G2: 0.2 mm
o G3: <0.1mm

187
Q

what does fluroescein do?

A

is a weak acid. It doesn’t stain, it fluoresces in the presence of more
alkaline fluid (such as mix of tear fluid and aqueous humor) and ‘stains’ corneal
epithelial cells by pooling in areas of dead or shedded cells. It fluoresces at 525-
530nm (use yellow filter).

188
Q

what does lissamine green do

A

stains membrane degenerate and dead cells. viewed in white
light.

o In dry eyes, the nasal conjunctiva stains more than the temporal and the cornea stains less the conjunctiva. Observe 1 eye at a time (use red filter)

Lissamine is better for conjunctiva instead of NaFl

189
Q

differential diagnosis for lumps on eyelids

A

hordeloum
chalazion
molloscum contagiosum
xanthelasma
papilloma
basal cell carcinoma
squamous cell carcinoma
malignant melanoma
epidermoid cyst
cyst of moll

190
Q

Adequate production and drainage of the aqueous layer is necessary for the
maintenance of:

A
  1. tear nutrients (e.g. oxygen and electrolyte supply to the cornea) and antibacterial agents (i.e. lysozyme produced by the major and accessory lacrimal glands).
  2. moist conditions on the eye surface (evaporation reduces surface temperature)
  3. the mechanical flushing action of tear movement

Aqueous deficiencies may be partial or absolute but invariably produce marked
symptoms of soreness or burning.
The osmolarity of the aqueous increases in dry eye and the resulting hypertonicity leads
to ocular damage.

191
Q

what happens when there is impaired lid function

A

The forces associated with lid-globe contact during blinking is important for mucus distribution. Restricted lid movement can lead to serious tear deficiency and exposure
keratitis

192
Q

what is Epitheliopathy

A

An irregular corneal epithelium (due to corneal lesions or keratoconus) can produce a
thin and unstable tear film.

193
Q

tear substitutes

A
  • Carbomers (GelTears, Viscotears) – semi-solid formulations of high molecular
    weight.
    o Drop frequency reduced from 20x to 4x
    o reduces natural elimination of tears
    o retention time is 7x longer
    o protective during sleep
    o high viscosity can cause blurring
  • Hypermellose – traditional choice of treatment for tear deficiency. Requires
    frequent instillation
  • Liquid Paraffin (Hycosan Night) – lubricates eye surface in case of recurrent
    corneal erosion. May cause blurry vision
  • Macrogels (Systane) – uses pH sensitive component to become more viscous in the eye
  • Paraffin (Ointment) – bland ointment are semisolid preparation of petrolatum
    and mineral oil and lanolin. Melt in eye and retained. Only use at night
  • Sodium Hyaluronate (Hysosan) – Viscoelastic high molecular weight polymer, increases goblet cell density and reduces inflammation of ocular surface.
    Improves tear stability and wettability.
  • Diet – Omega 3/6, fatty acids.
  • Ocular Environment – central heating, air humidifier
194
Q

Aqueous-deficient (ADDE)

A

Sjögren Syndrome (SSDE)
 Associated with systemic disease e.g. RA, lupus etc.

Non-Sjögren Syndrome (NSDE)
 Intrinsic
 Lacrimal gland deficiency
 Inflammation of infiltration of lacrimal gland
 Lacrimal gland obstruction
 Hyposecretory states i.e. reflex afferent block or secretomotor block (parasympathetic damage)

195
Q

what is Dacryocystitis

A

Bacterial infection of lacrimal sac – secondary to blockage on the nasolacrimal duct

196
Q

symptoms and signs of Dacryocystitis

A

Symptoms
* Sudden onset
* Pain
* tender swelling of lacrimal sac
* epiphora
* fever

Signs
* Red, tender swelling centred over lacrimal sac and extending around the orbit
* Purulent discharge from the puncta when pressure applied
* frequent conjunctivitis and pre-septal cellulitis

197
Q

college managment guidelines dacryocysitis

A

ALL Children EMERGENCY REFERRAL, Severe case if
px is systematically unwell, cases which do not respond to anti-biotics for 7 days
Urgent referral, mild cases responsive to systemic antibiotics – monitor for blockage of
duct. Manage to resolution

198
Q

management of entropion

A
  • Tape the lid to the skin of the cheek for temporary relief
  • Epilation of lashes can be done where Trichiasis is localised
  • therapeutic CL to protect cornea
  • Ocular lubricants
    Refer – Initial management followed by routine referral for surgery
199
Q

management of ectropion

A

College Management Guidelines – Mild cases require no treatment, tape lid at night to avoid corneal exposure, ocular lubricant

Refer–Severe cases requiring surgery

200
Q

management of trichiasis

A
  • Epilation of lashes
  • therapeutic CL for temporary relief,
  • Ocular lubricant
  • lid hygiene for associated blepharitis
    Refer – Routine referral for electrolysis, cryotherapy, argon laser photocoagulation, lid
    surgery if secondary to entropion
201
Q

what is a chalazion

A

sterile chronic inflammation from a blocked gland

202
Q

chalazion signs and symptoms

A

Symptoms
* painless lid lump, usually single, may be recurrent, may rupture,
* sometime blurred vision from induced astigmatism

Signs
* Well defined, 2-8mm nodule in tarsal plate
* lid eversion may show external conjunctival granuloma
* associated blepharitis
* induced astigmatism

203
Q

whats an external hordeolum

A

Acute bacterial infection of the lash follicle and its associated gland of zeiss or
moll

204
Q

whats an internal hordeloum

A

Acute bacterial infection of the Meibomian gland, usually staphylococcal: can develop into chalazion if untreated.

205
Q

signs and symptoms of hordeolum

A

Symptoms
* Tender lump in eyelid
* Epiphora
* Local redness of eye and lid

Signs
External – tender inflamed swelling on the lid margin, may point anterior through skin,
multiple abscesses involved entire eyelid

Internal – tender inflamed swelling within the tarsal plate that’s more painful than stye.
May point anteriorly through skin or posteriorly through conjunctiva

206
Q

management of hordeloum

A
  • most resolve spontaneously or discharge by resolution
  • remove lash from infected follicle,
  • manage associated blepharitis with lid hygiene
  • return if persist or worsen
  • topical antibiotics - when copious discharge
    Refer – In cases which do not discharge ( more with internal hordeolum)
  • severe or recurrent then management w systemic braod spectrum antibiotic like amoxicillin
207
Q

what is pre septal cellulitis

A

Bacterial infection of tissues lying anterior to the orbital septum common in infants
under the age of 10 Caused by Staphylococcal, Streptococcal

208
Q

what is orbital cellultis

A

Bacterial infection of the tissues lying posterior to the orbital septum (within the orbit)
severe and life threatening

209
Q

signs of orbital cellulitis

A
  • Proptosis
  • Restriction of EOM
  • pain with eye movement
  • reduced VA
  • reduced CV
  • RAPD present
  • pyrexia
  • fever
    -malaise
    -unilateral swelling of conj and lids
210
Q

reasons for fitting RGPs

A

aphakia
cornea with high DC
keratoconus
post graft surgery
more stable vision
more durable cls - up to 1 yr
* High o2 permeability
* Doesn’t dry out tear film due to 0% water content
* Resistant to protein deposits

211
Q

RGP Boston Simplus Multi-Action Solution
Ingredients:

A
  • Poloxamine – Removes lipids and environmental debris
  • Hydroxyalkyl phosphonate – Removes protein deposits
  • Boric Acid – eliminates bacteria and fungi
  • Sodium Borate – anti-fungal and Balances pH for natural lens wear, to match the tearfilm: 6.6 – 7.8.
  • Sodium Chloride - Maintains similar tonicity to the tearfilm to avoid discomfort and conjunctival hyperaemia
  • Hydroxypropylmethyl cellulose – Conditions and lubricates the lens surface
  • Chlorhexidine Gluconate - Disinfectant
  • Polyaminopropyl biguanide – Disinfectant and preservative
212
Q

how to use RGP MPS solution

A
  1. Soak lenses in solution for 4 hours or overnight in an empty lens case
  2. Wash your hands
  3. After soaking, rub both sides of the lens with 4 drops of the cleaner solution in the
    palm of your hand for 20 seconds.
  4. Rinse using the solution for approximately 5 seconds to remove loosened surface
    deposits
  5. Insert lenses
  6. Discard solution 90 days after opening
213
Q

Boston 2 Step Cleaning and Conditioning System
Ingredients

A

Boston Advance Cleaner (Step 1)
* Alkyl ether sulfate – surfactant to remove contaminants from the lens surface
* Ethoxylated alkyl phenol – alcohol to remove bacteria from the lens surface
* Quarternary phospholipids, Titanium Dioxide & Silica Gel – Aids to physically scrub
off proteins and deposits when rubbing
Boston Advance Conditioning Solution (Step 2)
* Wetting and cushioning agents:
o Cellulosic Viscosifier
o Polyvinyl Alcohol
o Polyethylene Glycol
* Preserved with:
o Chlorhexidine Gluconate
o Polyaminopropyl biguanide
o Edetate Disodium

214
Q

RGP 2 step cleaning and conditioning system

A
  1. Wash your hands
  2. Rub both sides of the lenses carefully with 4 drops of cleaner (Step 1) in the palm
    of your hand for 20 seconds
  3. Rinse both sides of the lens with a saline solution
  4. Soak your lenses for 4 hours with the conditioning solution (step 2)
  5. Add a drop of conditioner to the lens for extra cushioning and insert into your
    eye.
  6. Rinse your lens case with a sterile disinfecting solution and then wipe dry with a
    clean tissue. Avoid air-drying.
215
Q

RGP FITTING what to do when the difference in the Ks is < or equal to 1DC

A

fit on flattest K (round to 0.05mm)
(plus lenses tend to drop a little, consider fitting 0.05mm steeper)

216
Q

RGP FITTING what to do when the difference in the Ks is > 1DC

A

use formula:
BOZR=FlatK - (FlatK-SteepK)/3

217
Q

RGP fitting why are HVID and VVID measurements taken

A

 HVID dictates the total size of the lens
 TD ~ 1.5 – 2mm smaller than HVID
o HVID generally 11-12mm
 Generally, 9.30 and 9.80 TDs available
 VVID gives us indication of the fit
o Lid attached; minus lens more likely to lid attach as it is thicker in the periphery
o Interpalpebral
 Higher powers require greater td for stability

218
Q

RGP fitting Pupil diameter indicates what?

A

 BOZD = area with Rx (periphery of lens is for stabilisation)
 BOZD must be > pupil size in scotopic (dim light) to ensure pupil is smaller than BOZD in all lighting conditions
 If pupil > BOZD = issue with flare / haloes around lights
 High myopes may need larger BOZDs to avoid flare

219
Q

flat fitting RGP lens

A

 Nafl = central touch, large area of edge lift
 Flat fit creates a negative tear lens, resulting in plus over Rx

220
Q

steep RGP fitting

A

 Nafl = central pooling (smaller area of pooling = steeper lens)
 Steep fit creates a positive tear lens resulting in a negative over Rx

221
Q

RGP lenses what happens when over refraction done or when diameter increased

A

0.25DS over Rx = 0.05 BOZR change

Increase in diameter by 0.5 = flatten BC by 0.05

Increased diameter = increased sag
Because cornea is aspheric, increasing diameter = steepening lens, therefore you need to flatten it to keep Rx same

222
Q

most RGPs are which material

A

fluorosilicone acrylate
Silicone is softer so scratches more easily, hence modern RGPs are only on 1–2-year replacement schedules.

The addition of fluoropolymers to silicone acrylate increases the wettability & less susceptible to protein deposition

223
Q

the total diameter for RGPs

A
  • Usually ranges from 8.50-10.50mm
  • Ideally approx. 2mm smaller than HVID measurement
  • Influenced by the pupil size as it must be larger than the pupil in low illumination
    o If not px may experience halos at night/dark conditions
  • Higher powered lenses are better suited to larger TD so they are more stable
  • Altering the TD does not influence the NaFl pattern to a great degree on aspheric lenses
224
Q

what is lag and why do we measure it

A

the measurement of horizontal movement on lens excursion

Lag is important to measure when fitting contact lenses to assess how well the lens moves with the eye when it looks away from the primary gaze

Lag is the difference in distance between the lens edge and the limbus when looking in different directions. For example, if the distance from the lens edge to the limbus is 1.5 mm when looking straight ahead, but 2.5 mm when looking up, the lag is +1.0 mm

225
Q

hydrogel what is it and advnatge and disadvantages?

A
  • Hydrophillic polymer (Main material used is Poly-HEMA).
  • The oxygen permeability depends on the water content, the higher the water
    content the more oxygen that can pass through the lens.
    Advantages of Hydrogel:
  • Thinner lenses
  • Better initial comfort
    Disadvantages of Hydrogel:
  • Low oxygen permeability
  • Higher risk of eye infections and hypoxia-related issues
  • Not ideal for overnight wear
226
Q

silicone hydrogel

A
  • Allows 5x times more oxygen to pass through than hydrogels.
  • The oxygen permeability depends on the amount of silicone used, not the water content
    Advantages of Silicone Hydrogel:
  • High oxygen permeability
  • Extended wear and longer wear times available
  • Easier to handle as generally thickness aids sturdiness and enhances durability
    Disadvantages of Silicone Hydrogel:
  • Tend to be more expensive
227
Q

opteyes

A

o 160Dk/t
o 48% water content
o No UV protection
o Modulus 0.75
o Monthly/EW (i.e. can sleep in lenses) silicone hydrogel
o BC 8.6mm, Dia. 14.0mm
o Power ranges
 -0.25 to -6.00 (0.25)
 -6.50 to -12.00 (0.50)
 +0.25 to +6.00 (0.25)
 +6.50 to 8.00 (0.50)
o Extended range
 -12.50 to -20.00 (0.50)
 +8.50 to +15.00 (0.50)
o Stock in store
 +/-0.25 to +/-6.00
 -6.50 to -17.00 (0.50)
 +7.50 and +8.00
o Also have toric, toric XR (which has an extended range for sphere and cyl powers) and multifocal options

228
Q

SCLs: Adjusting rx for BVD: needs to be taken in account for rx

A

> +/-4.00

K= F/((1-dF))

K = new CL power
F = spec power
d = BVD (in metres)
229
Q

SCL specification is written out in the following way:

A

BOZR/TD/rx, lens name (modality) e.g. 8.4/14.2/-3.00DS Bioinfinity (monthly)

230
Q

how to adjust lens when flat fit vs steep fit

A

 Flat fit = steepen by increasing TD or reducing BOZR
 Steep fit = flatten by decreasing TD or increasing BOZR

231
Q

why is pupil size measurement taken for cls

A

to make sure the optic zone radius covers the pupil at all times.
If pupil size bigger than measured then distortion seen

232
Q

why is HVID measured

A

Horizontal visible iris diameter (HVID) is of value to the soft lens fitting and will act as a determinant of total diameter. The HVID must be at least mm less than the TD of the lens to be fitted

233
Q

linarial cls

A

spherical +8.00 -12.00DS
toric +8.00 –10.00DS, 2.25DC is the highest
water content 54%
Dk 80
0.4 modulus

234
Q

precision ones torics

A

+8.00 -12.00
-2.25DC
Dk 90
51% water content at core

235
Q

opteyes

A

+20 -20DS, highest cyl 5.75DC
Dk 128
48% water content

236
Q

To work out the power required for a certain working distance

A

1/dist(m) = D
1/0.5m = 2.00D

237
Q

when px works on screens what is the law for specs from work

A
  • The UK Health and Safety Executive (HSE) law states that employers must arrange an eye test for display screen equipment (DSE) users if they ask for one, as well as pay for it, and pay for glasses if an employee needs them only for DSE use
    o If an ordinary prescription is suitable, employers do not have to pay for glasses
    o In some cases an employer may choose to contribute towards specs which are not solely for DSE use, but this is entirely at the employer’s discretion
238
Q

what does the employer need to know from the ST eg VDU users

A

o The px is under no obligation to reveal any clinical information to his employer, though failure to do so may become an employment issue
o Under DSE regulations, the employer only requires a very small amount of info
 Confirmation that a test was performed
 Whether or not the px requires no specs, their own specs or special VDU spectacles
 The date of the next suggested examination

239
Q

DVLA group 1

A

o In good daylight, must be able to read the registration plate
 At a distance of 20m with letters and numbers on a car registered since 1st September 2001
 At a distance of 20m with letters and numbers on a car registered before 1st September 2001
o VA must be at least Snellen 6/12 (logMAR 0.5) with both eyes open or only eye if monocular (with or without correction)
o A VF of at least 120 degrees on the horizontal using a target equivalent to the white Goldmann III4e setting e.g. Estermann field test
 There should be no significant defect in the binocular field that encroaches within 20 degrees of the fixation above or below the horizontal meridian
 The false-positive score must be no more than 20%
o Bioptic telescope devices are not accepted by the DVLA for driving

240
Q

DVLA group 2

A

bus and lorry license
o Require a higher standard of VA than group 1
o VA (using corrective lenses where needed) of at least
 Snellen 6/7.5 in the better eye
 Snellen 6/60 in the poorer eye
o If glasses are worn to meet the minimum standards, they should have a corrective power not exceeding +8.00 in any meridian of either lens

VFs:
 An uninterrupted measurement of at least 160 degrees on the horizontal plane. VF (with at least 70 either side of fixation) and 30 above and below fixation
 No defect should be present within a radius of the central 30 degrees
o No other impairment of visual function, including no glare sensitivity, CS or impairment of twilight vision

241
Q

driving safety and vision

A
  • You should advise the px that they have a legal responsibility to notify the DVLA and provide them with further information on how to contact them
  • You should advise the px that you have a duty to notify the DVLA yourself if you think the px will not or cannot do so, and if there is any concern for the safety of the px and/or wider public
  • You should also consider whether you need to notify other healthcare professionals e.g. GPs who can also discuss this with the px
  • If driving is relevant to the px’s occupation, you should advise them to inform their employer
  • You should put any advice in writing and keep a clear record of your actions including any correspondence
  • If you have followed the above steps, but still consider that the px will not inform the DVLA, you should
    o First, inform the px that you intend to notify the DVLA and you have a duty to cooperate fully with the DVLA and provide all relevant information as requested
    o Notify the DVLA and provide all relevant information that is requested
    o Consider whether you need to notify other healthcare professionals e.g. GP
    o Keep a record of your actions and any advice given
    o DVLA make the final decision whether or not to revoke the px’s licence
242
Q

for which eye conditions does the DVLA need to be informed?

A
  • Cataract
    o Often safe to drive and may not need to notify the DVLA (even if bilateral)
    o More prone to suffering glare/halos when driving at night
  • Monocular vision
    o Driver must meet the same VA and VF standards as binocular drivers
    o Only for those who fail to meet these requirements are required to notify the DVLA
  • VF defects
    o Bilateral glaucoma/retinopathy/retinitis pigmentosa and other VF defects that cause partial or complete homonymous hemianopia/quadrantopia or complete bitemporal hemianopia MUST notify the DVLA
  • Diplopia
    o Must not drive and must notify the DVLA – DVLA will review request for group 1 licences if corrected with glasses/patch/prism
  • Nyctalopia
    o Must not drive and must notify the DVLA (both groups)
  • Blepharospasm
    o Must not drive and must notify the DVLA (both groups)
  • Colour blindness
    o May drive and need not notify the DVLA (both groups)
  • Nystagmus
    o DVLA not need be notified providing the vision standards for driving are achieve and providing any associated medical condition is declared
243
Q

which bifocal segment for which rx

A

o R = PLUS
o D = Minus

244
Q

aspheric lenses advantages and disadvantages

A

Aspherics:
o Thinner, Flatter, Lighter
o Eliminates spherical aberrations, as causes all light that hits the lens
surface to converge onto one focal point
o Better Cosmetic Appearance due to flatter front surface
o Reduces centre thickness for High Plus and Edge thickness for High Minus
o Better optics in patients >+7.00D

Disadvantages of Aspherics:
* No useable zone in periphery
* Distorted vision is notorious in minus lenses à the only real use for a minus
aspheric is to reduce edge thickness

245
Q

prism thinning for varifocals

A

Prism Thinning: Incorporated vertical prism to reduce the thickness and weight of
the lens
* R+L Lens feel equal, no relative prismatic effect
* Base down prism is applied to reduce central thickness of the lens

246
Q

MAR advantages and disadvantages

A

Anti-Reflective Coating: Decreases surface reflections inside the lens by phasing the reflected rays into ½ their wavelengths, causing destructive interference.
Multiple coatings are applied for different wavelengths. Ultimately this improves
the optical performance and removes glare for the patient.
o Advantages of MAR:
§ Improved visual performance
§ Reduced Glare
§ Increased Contrast
§ Improved Cosmesis
§ Mandatory for High Index

o Disadvantages of MAR:
§ Easily smeared due to hydrophobic coating
§ Expensive due to vacuum coating process
§ Prone to chemical damage from everyday products (e.g. hairspray)

247
Q

Uv400

A

Blocks UVA & UVB rays up to 400 nanometers. Good for patients with
cataracts & AMD.

248
Q

Decentration calculation:

A

Frame PD – Px PD / 2 = X (in)

This is important as if the lens is not decentred in to fit the Px’s PD, a prismatic effect will
be induced

249
Q

Levels of Thinning:

A

o 1.6 ‘T&L 25’: 20% thinner than a standard lens (2.50 to 4.00)
o 1.67 ‘T&L 35’: 33% thinner (4.00 to 6.00)
o 1.74 ‘T&L 50’: 42% thinner (6.00 +)

On all thin lenses an anti-reflection coating is recommended as high-index lenses refract
the light at a quicker rate and therefore create more reflections

250
Q

Cellulose Acetate: Most widely used

A

o Colour is produced by dye moulding.
o Manufactured in blocks and cut into sheets to cut the frame shape out of.
o Has reinforced sides.
o Finished in lacquer to improve scratch resistance.
o Reshapes at 60oC.
o Px may have allergies

251
Q

Cellulose Propionate

A

o Produced by injection moulding, dying and lacquer
o Stronger than Cellulose Acetate
o Greater elasticity and more flexible than Cellulose Acetate
o Greater resistance to ageing
o Lighter
o Reshapes at 70oC
o Hypoallergenic

252
Q

Polycarbonate

A

o Primarily used for safety eyewear (the one piece and side shields).
o Can be soft or high impact resistant.

253
Q

Lenticular Lenses

A

where the effective optical aperture is smaller than the frame aperture
o Used to reduce weight and thickness of high powered lenses, poor cosmetic appearance and reduced FoV
(especially for +ve lenses) rarely used due to availability of high index materials
o Standard lenticular, blended lenticular
o Made from plastic
eg bifocals

254
Q

photochromatic lenses

A

Photochromic – AgCl and CuCl added to glass at manufacture, uv exposure causes chloride to undergo oxidation to chlorine and silver ions reduced to form atoms presence of CuCl in low UV allows reverse reaction
o Photochromic – Plastic – spiroxazines – molecule that rotates to form a shape reducing light transmission
combination of several spiroxazines each with different transmission and temperature dependencies
combined to form a photochromic lens.
o Photochromic performance – Temp dependent (darker and faster in cold), Enhanced by MAR (increased UV
transmission)

255
Q

varifocals soft and hard designs

A

 Soft designs = long progression lengths, more gradual astigmatic gradient in lens periphery, but have smaller stable reading area and distortions in the distance
o Easier to get used to – less of a change per 1mm when looking down
o More intermediate area
o E.g., Admin worker
 Hard = wider stable reading area, wider progression and distortion free distance area; however, the distortions are more severe as they are crammed into smaller area
o E.g., driver

256
Q

High index = reduction in abbe number = increased chromatic aberrations

A

o ABBE number = measurement of the materials dispersion of light
o Chromatic aberration = white light splits into its colour components as the lens is unable to bring various wavelengths to the same focal point
o High abbe = desirable = low dispersion
 As refractive index increases density and amount of aberration increases and weight decreases (plastic) or increases (glass)

257
Q

Crown glass lens advantages and disadvantages

A

o Advantages
 Refractive index (N=1.523) is higher than that of CR39, so lenses are thinner
 Lenses are abrasion resistant
 Good constringence (V or Abbe number of 59)
* the higher the V value the lower the material’s dispersion of transverse chromatic aberration (less likely to disperse white light into ROYGBIV)
 Good transmission – 92% in uncoated state
o Disadvantages
 Poor impact resistance and shatters into sharp shards when broken
 Density high so lenses will generally be heavier than CR39

258
Q

CR39 (ophthalmic hard resin) advantages and disadvantages

A

o Advantages
 Low density and lenses are therefore lighter than crown
 Good transmission – 92% in uncoated state
 Good constringence (V values of 58/59)
 Impact resistance better than crown and then lens does not splinter when broken
 UV protection good (around 350nm) since UV absorbers are incorporated into the lens as standard
o Disadvantages
 Lower refractive index (n=1.498) than crown, so are thicker than crown lenses
 Abrasion resistance is poor, unless a hard coat is added

259
Q

Polycarbonate advantages and disadvantages

A

o Advantages
 Primarily impact resistance or ‘increased robustness’, making it ideal for sports and industrial purposes
 Becoming more popular for children and general-purpose specs
 Good UVC protection (cut off 400nm)
 Higher RI than CR39, so very light
o Disadvantages
 Abrasion resistance is poor, so are coated with silicone-based polymers – this reduces impact resistance slightly, but the material still maintains its ‘increased robustness’ standard
 Cannot be easily tinted

260
Q

how is the total power of lens found

A

The total power of a lens is a sum of the front and back surface of the lens
F1 + F2 =FT
e.g.
+4 + +2 = +6.00 D
+7 + -1 = +6.00D

261
Q

Optoms/DOs have a responsibility for safety specs

A

o Must assess the suitability of chosen appliance
o Must provide the most suitable ocular and housing type
o Must ensure the finished product complies with the px’s requirements and relevant standards
 Cannot repair safety specs (not even change a screw) – needs to be sent back to the manufacturer for them to carry out safety checks
 Can only really carry out adjustments

A visual task analysis

262
Q

VDU users laws

A

 VDU users are entitled to a free sight test paid for by their employer if they are having difficulty carrying out display screen work.
 If glasses are required specifically for VDU only then the employer must provide those for free (basic cost of lens & frame). This is specified by the Health & Safety Regulations (1992).

 The AOP recommends the following standards for a VDU operator:
o Ability to read N6 at the range of 33 – 70cm, with adequate VA for any required task at a greater distance
o Good binocular vision or well-established monocular vision
o Normal NPC
o Clear ocular media

263
Q

polycarbonate should not be cleaned with what

A

 Polycarb shouldn’t be cleaned with acetone or methyl chloride; should avoid extreme heat – not suitable for chemical engineers
 Consider glass if molten metal

264
Q

the employee responsibility for eye protection

A

o Must maintain the safety appliance in good working order
o Must report loss or damage of the appliance
o Must use the appliance as instructed

265
Q

the employer responsibility for eye protection

A

o Must assess the risks to workers
o Must supply an appropriate safety appliance
o Must maintain, repair and replace safety appliances as appropriate
o Must provide areas of safe storage when not in use
o Must advise employees regarding correct use of safety appliances and their limitations

266
Q

British/European standards for safety specs

A
  • BS 2092 has been superseded by EN 166, 167 and 168
  • These new European standards give four levels of impact resistance (see table in notes )
  • Lenses are referred to as ‘oculars’ and frames as ‘housings’
  • Each feature is represented by a specific symbol marked on the ocular or housing
  • The order in which the markings appear is standardised
  • These can be found in EN 166 and the College occupational optometry module 6
267
Q

saftey specs lens markings

A

o 1 ʹ Optical Class Rx +/- 0.06
o 2 ʹ Optical Class Rx +/- 0.12
o 3 ʹ Optical Class Rx + 0.12 (Specs and Goggles Only)
o 3 ʹ Optical Class Rx -0.25 (Specs and Goggles Only)
o S ʹ Increased robustness (toughened or thickened CR39)
o F ʹ Low energy impact (Polycarbonate and Trivex)
o B ʹ Medium energy impact (Goggles and Faceshields Only)
o A ʹ High energy impact (Faceshields Only)
o 9 ʹ Non-adherence of molten metal/ hot solids (Goggles and Faceshields Only)
o N ʹ Resistance to fogging
o K ʹ Resistance to surface damage (damage by fine particles)

268
Q

saftey specs frame markings

A

Frame Marking ʹ
o F ʹ Low energy impact (polycarb lenses)
o B ʹ Medium energy impact (Goggles and Faceshields Only)
o A ʹ High energy impact (Faceshields Only)
o 3 ʹ Liquid droplets / splashes (Goggles and Faceshields Only)
o 4 ʹ Large dust particles (Goggles Only)
o 5 ʹ Gas and fine dust particles (Goggles Only)
o 8 ʹ Short circuit electric arc (Faceshields Only)
o 9 ʹ Molten metals / hot solids (Goggles and Faceshields Only)

269
Q

saftey specs order of markings

A
  • Scale Number (filters only)
  • Manufacturer’s Mark
  • Optical Class (1 (is the best),2 or 3)
  • Mechanical Strength (A, B, F, S)
  • Fields of Use (9 Molten metal/hot solids)
  • Scratch Resistance (K)
  • Fogging Resistance (N)
  • Radiant Heat
  • CE mark
270
Q

welders flash

A

It causes burning of the cornea

Symptoms
o Will not be obvious immediately, although will be several hours after the exposure, 6-12 hours latency period
o 1. Painful
o 2. Sensitive to light
o 3. Watering
o 4. Become increasingly difficult to open the eyes due to spasm of the eyelids muscle
o FB sensation, blurring of vision, redness, associated skin burns from UV exposure

271
Q

welders flash tx

A
  • If there is no improvement after 30 mins of treatment, contact A&E
  • Treatment
    o Cold compresses
    o Local anaesthetic can be instilled to help with the pain
    o Drops and lubricating ointment
    o If pain becomes unbearable to take painkillers – as you would for a headache
    o Symptoms last 6-24 hours usually completely cleared by 48 hours
272
Q

Commotio retinae

A

usually due to blunt force resulting in whitening and opacification of retinal area (pseudo-cherry red spot)

273
Q

what to do when chemical injury

A
  1. Wash out the eye IMMEDIATELY: normal saline or head under a cold water
    tap/bucket (eyes open)
  2. After 1 litre of irrigation (15-30 mins), review pain levels
  3. Instil topical anaesthesia if pain level if high
  4. Evert the lid and clear the eye of debris
  5. sweep with cotton bud
  6. Wait 1 minute, measure pH of tear meniscus (lower lid) – pH 7-8 acceptable
  7. Continue irrigation if necessary, repeat pH every 5-10 minutes
  8. Admit to hospital
274
Q

what is Anisometropia

A

Where the prescriptions between R&L are different (1.50/2.00DS/DC)

Simple
o One eye is emmetropic and the other is either myopic or hyperopic

Compound
o Both eyes are either hyperopic or myopic and one eye has a higher refractive error than the other

Mixed (antimetropia)
o One eye is myopic and the other is hyperopic

275
Q

what is anisokonia

A

For patients with anisometropia of more than 2, they may experience a difference in the
size and shape of visual images and magnification: Aniseikonia.

276
Q

what problems can be caused with anisometropia?

A

Anisometropia becomes problematic when the difference is >2.00D.
When looking away from the optical centre of the lens (e.g. looking down to read), issues
can include:
* Blurred Vision
* Double Vision
* Unable to tolerate reading for long periods as a result of >1D of VDPE

277
Q

why do problems happens with anisometropia

A

Because for each dioptre difference in power between the eyes, there is 1 dioptre of vertical differential prismatic effect at the near visual point (10mm below, 2mm in from
the optical centre).

According to British standards, patients can tolerate 1 dioptre of VDPE, but the tolerance is much greater horizontally (10 BO – 4 BI at dist, 7 BO – 7 BI at near)
Actual Vertical Prism Reserves range between 2-4PD

278
Q

Symptoms of Aniseikonia

A
  • Visual discomfort
  • Visual distortion
  • Difficulty with stereopsis/BV.
  • Dizziness, H/A, Nausea.
279
Q

Single Vision Dispensing for an Anisometropic Patient

A
  • Aspheric Lens to the Most Positive Powered Eye. The retinal image size is reduced as the aspheric surface is approx. 2.00D flatter.
    Thinner lenses change lens shape - less maginfication - changes retinal image size
  • Iseikonic lens to the Least Positive Eye. The thickness is increased by increasing the base curve (to approx 8.00D) to increase the spectacle magnification of the least positive eye.
280
Q

vertical differential prism

A
  • Usually not an issue with SV lenses as the px will simply move their head in order to look through the optical centres (OC)
    o There is no prismatic effect at the OCs
  • However, if must be considered in the cases where the px has no choice but to look away from the OCs of the lenses, as the near visual points (NVP) do not coincide with the OCs e.g. bifocals and varifocals
  • Prism will be induced according to Prentice Rule: P = cF
    o c = decentration in cm
    o F = power in DS
    o Assume NVP is 10mm below the OC when calculating at near
  • A positive lens exerts base out prism
  • A negative lens exerts base in prism
  • If the lens power for each eye is different, there will be a differential vertical prism at near
    o Vertical prismatic power difference = difference in dioptric power between the 2 lenses in the vertical meridian (i.e. 90)
    o A max of 1-2 vertical differential prism may be tolerated (<1 unlikely to give rise to symptoms)
  • Image is always shifted towards the apex of the prism
    o All lenses that aren’t plano, have the potential to create prism
281
Q

spectacle magnification equation

A

Spectacle Magnification = Shape Factor x Power Factor

Shape Factor: a ratio of surface curvatures that describe the shape of the lens and typically ranges from values of -2 to +2

Power Factor: The dioptric power of the lens considering the power and vertex distance
of the lens.

282
Q

other solutions for Single Vision Dispensing for an Anisometropic Patient

A

give the px two pairs for different distances, as the optical centres will be set for viewing that particular distance. Ultimately this eliminates vertical differential prismatic power.

Advise the px to tilt their head downward when reading in order to view through the optical centre of the lens – however this is only successful for quick reading,
as may give px neck pain due to the uncomfortable head position.

283
Q

Bi-focal Dispensing for an Anisometropic Patient

A
  • Slab off near-portion for the most negative eye as it induces the most base down prism - balances eyes
    o Most ideal for minus lenses as the base up prism induced by the slab-off neutralises the base down prism of the main lens) (minimum slab off
    available – 2 dioptres base down)
    o The most negative eye induces the largest amount of base down prism which can be removed by slabbing-off.
    o The slab-off line should be set at the lower limbus.

When minus lenses are slabbed off base down prism is removed. When positive lenses are slabbed off base up prism is added.

BIF -thinning doesn’t change anything, problem is looking into near add

From pre reg academy*
P=cf
=0.01x-2.25 (difference betwen R and L eye) axis needs to be taken into consideration, if axis is at 180 it can be ignored, need to tranpose the LE to get axis at 180)
=2.25D Base down RE, how much prism is reduced when they are looking (avergae person can only cope with 1D of vertical prism). Slab off prism could used in reading portion - induces base up prism, adds prism in the near add in the RE
Slab on is base down
slab off prism is base down
opposite if plus precription, for the opposite eye as well

284
Q

anismetropic px, bifocals different round seg sizes

A

o Larger segment given to the most positive eye. It works on the principle that a larger segment will induce the most base down prism

Formula used:
Segment radius (cm) x near add = amount of relative vertical prism overcome

o Most ideal for Positive lenses: the base down prism induced in the
segment eliminates the base up of the distance power in the main lens)
o Only successful in round segs.
o To find out how much difference in size to give:
Difference in seg diameters (mm) = 20 x differential prism / Add

Pre reg academy*
Different Segments induced different prism
R seg the OC are where the radius of the segments are, would use different sizes. Bigger seg in the most plus so in the LE
R seg induces prism the other way round, different segment sizes

(For normal px’s we Usually do R seg for plus rx
D seg minus, less jump since the prisms cancel out, D seg prism is at the top of the segment)

285
Q

Franklin Split method Bifocals

A

Franklin Split can be used instead - 2 lenses that are held together by a frame - can put OC where needed for each lens
most do E seg instead

286
Q

main problem for anisometropia disp for SV vs BIF

A

SV - different retinal image sizes
BIF - differential prism

287
Q

what is image displacement

A

Is the prismatic effect induced by the combination of the bifocal type and the power of the distance lens rx in the reading position

288
Q

Varis for anisometropia disp

A
  • Need to specify fitting cross position in both eyes (PDs/OCs)
  • Horizontal centration = monocular PDs
  • Monocular vertical centration = distance above or below HCL
  • Do not necessarily get image jump with varis, but will still suffer image displacement due to vertical differential prism – tend to cope with this gradual introduction of prism better
    o Therefore in anisometropia pxs it is better to dispense a varifocal lens with a short corridor
    o This will reduce the amount the px has to look down the lens, and hopefully minimise the amount of vertical prism induced by looking away from the OC
289
Q

seperate SVN disp for anismoetropia

A

Position OCs 5mm below the pupil centre (a standard practice) which allows the px to read with the visual axis not too far away from the OCs

For each mm decentration downwards, the Pantoscopic tilt will need to be increased 2 degrees

290
Q

how does slab off work for bifocals

A

 A prism wedge is added to the back of the most minus/least plus eye
 Base up to correct base down effect – neutralising effect at near
 Prism is effectively removed from the reading portion of the lens, resulting in a horizontal visible edge across the front surface
 The line coincides with the top part of the segment
 Can be done with varifocals too
 Reverse slab-off (short-cut technique to create lens)

291
Q

which bifocal segment to give for rx types

A

 Prism x 2 = difference in segment diameter x add
 The larger round segment has its optical centre lower down and therefore introduces more base down prism then does the smaller segment
 The larger segment is used to neutralise the vertical differential prism by adding prism to one lens
 Myopic anisometropia – the lesser myopic eye will need the larger segment
 Hyperopic anisometropia – the higher powered lens introduces more base up prismatic effect at the NVP, so this lens will need the larger base down effect of the larger segment
 Not usually done as it is not very cosmetically appealing

 The base down effect of a round segment is exaggerated by a negative distance lens – hyperopes are better served by a down curve round segment
 Myopes benefit from a D shaped or executive in which the near optical centre is better controlled (reduced jump)

292
Q

90D volk field of view and magnification

A

FOV: 89
Mag: 0.76

293
Q

superfield volk field of view and magnification

A
  • FOV: 116
  • Mag: 0.76
294
Q

posterior subcapsular grading

A

o 1+ = 1-2mm
o 2+ = 2-3mm
o 3+ = >3mm

295
Q

cortical cataract gradings

A

o 1+ = 1/8 to ¼ of total area
o 2+ = ¼ to ½ of total area
o 3+ = ½ or more of the total area

296
Q

pupils: when does the near response needs checked

A

near response only checked if direct response is abnormal

297
Q

what is a partial rapd

A

Sluggish response / slight dilation = partial RAPD

298
Q

afferent pathway

A

Nerve that carries information towards the central nervous system

299
Q

efferent pathway

A

Nerve that carries information away from the central nervous system

300
Q

sphincter muscle

A
  • Pupil size is mainly determined by the contraction & relaxation of the sphincter muscle.
    Þ It is a thin circumferential ring of smooth muscle fibres
  • The sphincter muscle responds to signals from the short ciliary nerve
    Þ This constricts the pupil
  • The sphincter muscle is innervated by cholinergic parasympathetic fibres (rest and digest)
301
Q

dilator muscle

A
  • The dilator muscle has a secondary effect on pupil size
  • The dilator muscle responds to signals coming from the long ciliary nerve
    Þ This dilates the pupil
  • The dilator muscle is innervated by adrenergic sympathetic fibres
    The Sphincter & Dilator muscles are antagonistic muscles
302
Q

How does the pupil Dilate in dark lighting?

A
  1. The sphincter muscle relaxes
    Þ The sphincter muscle has the biggest effect on pupil size
  2. The dilator muscle contracts
303
Q

How does the pupil constrict in bright lighting?

A
  1. The sphincter muscle contracts
    The sphincter muscle has the biggest effect on pupil size
  2. The dilator muscle relaxes
304
Q

pupils what does it mean when there is no direct reflex?

A

problem anywhere in nerve pathway

305
Q

pupils when direct response but no consensual response

A

but no consensual = problem with efferent pathway of consensual eye

306
Q

RAPD

A

 Swinging flashlight – RAPD
Which indicates:
 RAPD indicates - gross retinal abnormality (VA 6/60 or worse) in one eye or asymmetric, impaired optic nerve function, asymmetric chiasmal compression
 Correlated with abnormal vision
 Eye with RAPD will dilate when light is shone as ability to perceive bright light is diminished

307
Q

anisocoria

A

 Difference of >0.4mm
 25% of normal have this in dim light, 10% in bright light
 If anisocoria present – size difference must be measured in bright & dim light
 If difference remains constant = likely to be normal
o 20% of population have physiological anisocoria
 Difference greatest in dim light
o Possibly normal
o Possible problem with dilation of smaller pupil
o Suggests lesion affecting sympathetic innervation of dilator
 Difference largest in bright light
o Possible problem with constriction of larger pupil = REFER
o Suggests a lesion affecting parasympathetic innervation of sphincter
o Abnormal eye movements suggest preganglionic lesions; normal eye movements suggest post ganglionic lesion
 Pathological Anisocoria = defect in the efferent (motor) pathway

308
Q

Horner’s syndrome

A

 Anisocoria greater is dark conditions (affected pupil cannot dilate)
 Affects sympathetic nerve supply
 Signs: miotic pupil, ptosis, sweating down one side of face (hemifacial anhidrosis), reduced IOP on effected side
The pupil in the affected eye also dilates more slowly or less than the other pupil in response to light
 Cause: commonly lung tumour
 Management: urgent referral / record if longstanding
 Diagnosis is usually confirmed pharmacologically using apraclonidine drop

309
Q

Holmes-Adie pupil

A

 Common in young woman & usually unilateral
 Anisocoria greater in light conditions (affected pupil cannot constrict)
 Affects parasympathetic nerve supply
 Symptoms: reading problems & glare/photophobia
 Signs: dilated pupil with poor/tonic reaction to light – restricts better when accommodating
 Cause: damage to the post-ganglionic supply to the ciliary ganglion & sphincter pupillae or viral infection
 Management: Urgent referral to check for underlying cause
o Pilocarpine check test: disease/dilated eye constricts more than the other after pilocarpine instillation as the sphincter becomes very sensitive in the defect eye & absorbs more

310
Q

Argyll Robertson Pupil

A

 Very rare
 Signs: Bilateral miosed & irregular pupils; dilate poorly in darkness
 Accommodative (normal response to near) but not reactive to light (light/near dissociation)
 Cause: neurosyphilis / lesions in the rostral midbrain/ long term DM/ alcoholism

311
Q

CN3 Palsy pupils

A

 Pupil may be dilated (compressive cause) or normal (if caused by diabetes)
 Other signs include ptosis, eye down & out (horizontal & vertical diplopia)
 Cause: Aneurysm of the posterior communicating artery (PCA) or diabetes
 If diabetic CN3 > pupil sparing as DM is vascular (= no aneurysm compressing pupillary fibres)
 Management: emergency referral to exclude aneurysm

312
Q

Sympathetic pupil pathway (efferent pathway = brain > eyes), problem then what do we think

A

 Sympathetic innervation = dilation = dilator pupillae
 Sends signals from Edinger Westphal nuclei to both pupils via the ciliary ganglion & then CN3 (oculomotor nerve)
 Efferent defects are due to damage to the efferent innervation of the pupil and will result in unequal pupil size (anisocoria)
 If affected; anisocoria seen; no RAPD
o Congenital (causes heterochromia also) – reassure & record
o Horner’s syndrome
o Holmes Aidie Pupil
o Intraocular surgery
o Trauma
o Uveitis
o Acute angle-closure glaucoma
o Tumours of iris or ciliary body
o Anterior segment neovasc

313
Q

Parasympathetic pupil pathway (afferent pathway – eye to brain)

A

 Parasympathetic innervation = pupillary constriction = sphincter pupillae
 Signals - pupil -> Edinger Westphal nuclei via the optic nerve
 If affected – reduction in pupillary response to light, may only be detectable by swinging flashlight
 RAPD present - no anisocoria
 Most caused by lesions in the retina & optic nerve i.e.,
o AION
o Glaucoma
o Optic Neuritis
o Toxic Optic Neuropathy
o CRAO / CRVO
o Extensive retinal detachment

314
Q

pupils how to distinguish where the lesion is for parasympatheic branch of the efferent pathway

A
  • Prior to the Ciliary Ganglion
    Causing:
    Þ Absent accommodation
    Þ Fixed/Dilated pupils
    Þ Paresis of some of the EOMs
  • Post the Ciliary Ganglion
    Þ Post Ciliary Ganglion damage is known as Adie’s Tonic Pupil
315
Q

parallelopiped - how to do it and set up

A

Setup
* Angle: 45 °
* Slit: 1-2mm in width
* Filter: None
* Magnification: 16-25x
* Illumination: medium

Observation
* Detect and examine corneal structures and defects
* Higher magnification preferred to evaluate both depth and extent of corneal
scarring or foreign bodies.

316
Q

specular reflection - how to do it and set up

A

Bring SL in set up position
* Angle: 60°
* Position of the illumination arm 30°; Position of observation arm 30°; Angle of
illuminator to microscope must be equal and opposite.
* Slit: width 4mm
* Filter: Start with no filter
* Magnification: 16x-40x
* Illumination: medium to maximum

Observation
* To visualize the integrity of the tear film (lipid layer), corneal and lens surfaces
* To visualize the endothelium
4. Start with lower magnification (10X to 16X).
5. Direct a relatively narrow beam onto the cornea
6. Switch to the highest magnification available
Þ Endothelium is best viewed using only one ocular.
*Focus on tear film and locate the bright corneal reflection/Purkinje image
* Under specular reflection anterior corneal surface appears as white uniform surface
and corneal endothelium takes on a mosaic pattern

317
Q

Yellow/Wratten 12 filter

A

Can be used in addition to the Cobalt blue filter
to enhance contrast.

318
Q

Red free (green)

A

Enhances the contrast of blood vessels on the
corneas of contact lens wearers and
haemorrhages seen under the conjunctiva

319
Q

diffuse illumination

A

Setup
* Angle: 45°.
* Widest beam.
* Diffusing filter.
* Magnification: 10-16x
* Illumination: medium to high.

Observation
* Observe: eyelids, lashes, conjunctiva, sclera, pattern of redness, iris, pupil, gross
pathology, and media opacities

320
Q

optical section

A

Set-Up
* Angle: 45 °
* Slit: width minimum 0.01mm
* Filter: no filter
* Magnification: 25-16x
* Illumination: medium

Observation
* Used to localise: Nerve fibres, Blood vessels, Infiltrates, Cataracts, AC depth.
* To discover thickening, thinning, and distortions in the corneal contour.
* To determine the depth of foreign bodies or opacities in the corneal substance. (a
percentage of the total corneal thickness)
* To see a wide slice of stroma. (The angle between the microscope and
illuminating arm can be increased.)

321
Q

direct retro illumination

A

The beam is focused in an area adjacent to ocular tissue to be observed.
* Angle: Variable
* Slit: Parallelepiped
o Iris: maximum height
o Retina: Pupil size
* Filter: Start with no filter
* Magnification: 10-16x
* Illumination: Maximum
DECOUPLED

Observation
* Used most often in searching for Keratic precipitates and other debris on corneal
endothelium.
* The crystalline lens can also be retro illuminated for viewing of water clefts and
vacuoles of anterior lens and posterior subcapsular cataract

322
Q

indirect retro illumination

A

The beam is focused in an area adjacent to ocular tissue to be observed.
* Angle:
o Observer central to area of interest
o Illumination angle 45 deg nasally
* Slit: Parallelepiped
* Filter: Start with no filter
* Magnification: 16x
* Illumination: Maximum
DECOUPLED

Observations
* Infiltrations, small scars, corneal vessels, micro cysts, vacuoles
* Feature on the cornea is viewed against a dark background

323
Q

explanation of cataract

A

Cataracts are formed when the clear lens inside the eye becomes progressively more cloudy or
misty, which can mean vision is not quite as sharp. This is a slow gradual process that usually happens to most people as we get older. The early stages of a cataract do not necessarily affect your sight.

If the cataract begins to affect your daily life, a 15 minute surgery can be conducted to change the lens in your eye to a clearer artificial lens in order to improve your
vision.

324
Q

explanation of floaters

A

these are collagen fibres
These can appear to float in front of
your vision. It usually occurs due to a jelly inside of your eye starting to become a little-more liquid like with age, so sometimes the number of floaters increases as you get older.

However, a sudden and dramatic increase in floaters can be a sign of problem inside the eye, so you should always see an optometrist if this should occur.

325
Q

explanation of PVD

A

PVD is a common condition that occurs in about 75% of people over the age of 65. As we get
older the jelly like substance in the eye called the vitreous shrinks and becomes more liquid. As is
it shrinks it collapses away from the light sensitive layer of the eye called the retina. some people
may notice symptoms such as floaters or flashing lights as a result, but it does not in itself lead to
visual loss. However, if the floaters suddenly increase and are accompanied by flashing lights or a
shadow in your vision, you must visit your optometrist immediate as this can indicate something
more serious called a retinal detachment. However, this is a rare complication.

326
Q

dry eye explanation

A

is a common condition that may be caused because your eye doesn’t produce enough tears or because the tears evaporate too quickly. Dry eye can make your eye feel scratchy or irritated. In severe cases, it may temporarily make your vision blurry. Its uncomfortable but rarely
causes serious eye damage and is easily treatable / manageable.

327
Q

blepharitis explanation

A

Blepharitis is an inflammation of your eyelids. It can make eyelids red and itchy and can also lead to burning, soreness or stinging in your eyes. It is a chronic condition and can be uncomfortable
but rarely causes serious eye damage and is easily treatable / manageable.

328
Q

Lid wiper epitheliopathy

A

o Alteration in epithelium of advancing lid margin due to friction during lid movement across the lens surface
o Tear film thickness insufficient to separate lid and ocular surface

329
Q

Post cataract surgery drops

A

chloramphenicol 0.5% 4x a day for 5 days
Dexamethason 4x a day for 28 days

330
Q

RGP - when flat fit what power is the tear film so what is the over refraction

A

flat fit – will have a negative tear film then it would have a plus over refraction

331
Q

ICON RGP lens water content, DK, rx change, material

A

Boston EO and Boston XO material which is Fluoro silicone acrylate

Dk XO=200, Range 6/EO=58

-25.00 to +25.00D in.025 increments
Fit on flattest K
Outside the range (- 11.00 to +16.00D) ICON back surface design can be applied

Larger lens diameters usually deliver better lens stability and centration, so 9.80mm diameter lenses will be supplied unless otherwise stated or requested by the practitioner - comes in 9.3 to 9.8

Base curves 7.00-9.00mm in 0.05mm increments

332
Q

what are common RGP materials - advantages and disadvantages

A

Silicone acrylate - more prone to lens flexure
Flurosilicone acrylate- better wetability, fewer deposits, but can be britte if too thin

333
Q

what wavelength does polarised lenses block

A

Polarized lenses block horizontal light waves, including some blue light wavelengths, but they don’t block 100% of blue and green light between 400 and 550 nanometers.

334
Q

super readers

A

offers larger intermediate and near reading areas
super soft design

335
Q

super digital - soft design

A

distortion extends to distance area which affects peripheral vision
px will have to move their head more for when viewing objects in periphery
larger intermediate zone
narrower reading area
good for 1st time presbyopes (especially VDU)

336
Q

definition elect - hard design

A

larger distance area, narrow intermedaite corridor and wider reading area
aberrational astigmatism confined to limit nasal and temporal areas
distance virtually abberation free
good for prev bifocal wearers

337
Q

How often do saftey spec needs replaced

A

Generally every 2 yrs

338
Q

Is a lens is scratched for saftey specs - is it still okay to be used?

A

No

339
Q

What would you advise a welder in terms of eye protection

A

A9KG
Each letter and numbers shows meeting standard - resistant to head etc

340
Q

anti reflection coating

A

quarter of a wavelength thick

half a wavelength out of sync - cancels the wavelength out

341
Q

reticular drusen

A

reticular drusen are above RPE and more yellowish and in a network pattern and are more often extend to periphery than normal drusen

342
Q

vitelliform lesion

A

Vitelliform lesions are beneath the macula and are round yellowish and tend to be isolate.
Tend to be more symmetical between the eyes
Can be treated with antiVEGF

Pre Reg (7 decks)

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