Visit 2 Flashcards
8i
what does migraines present as
- 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
what do tension HAs present as
- 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
what do cluster HAs present as
- 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
GCA classic presentation
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
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.
raised Intracranial pressure presentation
- 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
questions to ask about diplopia
- 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?
aacg present as
severe temporal HA with associated pain around affected eye
nausea
vomiting
red eye
flashes vs migraine symptoms
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
optic neuritis HA
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
Giant Cell Arteritis (A&E)
- 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
Carotid Artery Dissection (A&E) presentation
Split in vessel wall -occlusion of lumen - stroke
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
Subarachnoid Haemorrhage (A&E) presentation
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)
Trigeminal Neuralgia
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
health and saftey
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
when should MPS be discarded
3/12 after opening
for expiry dates, is it the beginning or the end of the month
the end of the month of jul 2024
- cannot use after july 31st
Fire exists in the store
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
first aid in store
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
clinical waste
- 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
- How should sharps e.g. for FB removal be disposed of?
in a sharps box
o Sharp boxes are colour coded according to whether they are infectious or not
Reusable probes (e.g. tonometer, pachymeter) should be decontaminated IMMEDIATELY by:
- Rinse with saline
- Wash with liquid soap
- Soak in sodium hypochlorite 1% for 10 minutes
- Rinse with saline for 10 mins
- Dry
- Alcohol wipes alone do not remove prion proteins from contact devices.
adaptative period for rx - for child
18 weeks
what is mohindras technique?
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
Common Risks of Developing an Anomaly of Binocular Vision
- 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
what problems does amblyopia cause
- Reduced Snellen and grating acuity
- Loss of contrast sensitivity
- Shape distortion
- Motion deficits
- Crowding effect
why do we ask if prematurity for kids
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
what if child has Down’s syndrome and cerebral palsy (and other disabilities)
- 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
what is the ideal birth weight
ideally 7 pounds and 6 ounces, or 3.3kg
what is the expected rx type for an infant
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
what to ask in history for suspected strabismus
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
what is amblyopia
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
what is recorded for a latent deviation
direction, size, speed of recovery, changes at distances, with/without specs
what is recorded for a manifest deviation
direction, size, changes at distances, accommodation, with/without specs
stereopsis evident from which age
6 months
what is emmetropisation
Emmetropisation: expected reduction in neonatal refractive error during normal growth
o Most active phase 12-18 months
o Can eradicate 3.00DS / 1.50DC
what is the active and passive stages of emmetropisation
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
what is the critical period
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)
what is the sensitive period
Sensitive period 5-8 years; still vulnerable to damage and may respond to treatment
what are the 2 types of fusion needed for BV and stereopsis
motor and sensory fusion
what is motor fusion
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
what is sensory fusion
- Sensory fusion
o Appreciate 2 similar images and interpret as one
o How the eyes perceive and how the brain utilises
what innervates LR
6th Nerve (Abducens)
what inneravtes SO
4th Nerve (Trigeminal)
what innervates SR IR IO MR
3rd Nerve
(Oculomotor)
what is the action of LR
abduction
what is the action of MR
adduction
what is the action of SR
elevation
intorsion
adduction
what is the action of IR
depression
extorsion
adduction
what is the action of SO
intorsion
depression
abduction
what is the action of IO
extorsion
elevation
abduction
what is the expected vision at birth
6/300
what is the expected vision at 3 months and which test would you use?
what is the expected refraction?
6/90-6/60
FCPL
+3.00ds
what is the expected vision at 6 months and which test would you use?
what is the expected refraction?
expected stereo?
6/36-6/60
keeler FCPL
+2.50DS
stereo 600
what is the expected vision at 1 yr and which test would you use?
what is the expected refraction?
expected stereo?
6/18
cardiff acuity cards
+2.00DS
210-170 stereo
what is the expected vision at 2 yrs and which test would you use?
what is the expected refraction?
expected stereo?
6/12-6/9
cardiff/kays pictures/ sheridan gardiner
+1.25DS
100-85 stereo
what is the expected vision at 4 yrs and which test would you use?
what is the expected refraction?
expected stereo?
6/9 -6/6
snellen
+0.50DS
40-30 stereo
normal BSV: whats panums area and horopter
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
for amblyopia - how often should a px be reviewed
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
muscle sequlae
- Under action of the primary affected muscle
- Overaction of the contralateral synergist – Hering’s Law
- Overaction of the ipsilateral antagonist – Sherrington’s Law
- Inhibition palsy of the contralateral antagonist
what is abnoraml retinal correspondence
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
what is suppresion
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
what is normal retinal correspondance
both foveae have common visual directions - produce a single image
what is an incomitant devation and what is concomitant deviation
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.
what size is a small/med/large deviation?
Any deviation <4 prism D cannot be seen
Small – 4-8D
Moderate – 8-16D
Large - >16D
what is fixation disparity
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,
what causes an individual to get an hetereophoria
anatomical causes, refractive causes, uniocular activity and trauma
what happens when an heterephoria decompensates
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
Concomitant deviations in adults require management if:
- Cosmetically unacceptable / patient would like surgery to improve alignment (surgery usually when angle >20^)
- 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
what causes someone to get an heteroptropia
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
muscle balance test, eg maddox rod, what does it do
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
how and why are fusional reserves measured
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
symptoms of decompensated heterophoria
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)
what can cause decompenstated phorias
- 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
management of decompensated phorias
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
how to use maddox rod
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
meaning of pinhole results
o No improvement – indicates pathology
o Improvement – issue with rx
o Worse with pinhole – macular problem
principle of duochrome
based on the principle of longitudnal chromatic aberration, whereby short wavelength light (green) is refracted more than the light of longer wavelengths (red)
why do we do +1.00 blur test?
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
why do we want duochrome to be on green for cross cyl
green duochrome to ensure circle of least confusion is on the retina
what is the vitreous
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
attachments of the vitreous
o Vitreous base/ora-seratta
o Posterior lens capsule
o Optic disc
o Macula
o Along the retinal vessels
Where is the strongest attachment of the vitreous
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.
what do the posterior and anterior hyaloid membrane do
Posterior hyaloid membrane separates rear of vitreous from retina
Anterior hyaloid membrane separates front of vitreous from lens
what is the ora seratta
junction between the ciliary body at the retina
how to examine anterior vitreous
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
what is a PVD
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
why do floaters occur
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
management of PVD
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
what is lattice degeneration
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
signs of RD
*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
what is a retinoschisis
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
retinoschisis signs and symptoms
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
Differential diagnosis of retinal detachments
PVD
Choroidal mass – urgent referral
Retinoschisis – no referral needed/observation in community practice
what is a retinal detachment
- 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
what causes vitreomacular traction
caused by the vitreous gel in the eye remaining attached to the macula after a posterior vitreous detachment
what is the purpose of binocular balance
goal of equalising accommodative effort in the 2 eyes and achieving the bet possible binocular refraction
risk factors for PVD
Increased age, common in 50+
Axial length – myopic eyes more at risk (experienced 10 yrs earlier)
Following surgery i.e. cataract
Trauma
what is a horseshoe tear
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
giant tear
Starts with PVD, typically in older patients
Large break, high risk of complications, worst prognosis
atrophic hole
No PVD; typically, in young (myopic patients)
Tide mark appearance
Most likely to be asymptomatic
diaylsis RD
No PVD; typically, in younger px’s
Detachment may be large, usually infero-temporal
May be due to trauma
tractional RD most common cause
Mainly caused by fibrosis from severe diabetic retinopathy
does tractional RD cause symptoms
Flashes/floaters usually absent because vitreoretinal traction develops insidiously, and is not associated with PVD
signs of tractional RD
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
what is an exudative RD
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
symptoms of exudative RD
No flashes, floaters if Vitritis, field defect may develop & progress rapidly
signs of exudative RD
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
management for a RD
- 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
what is white without pressure
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
when would you do an emergency referral for RD
- RD with good VA (Macula On),
- Vitreous or pre-retinal haemorrhage,
- Pigment in anterior vitreous,
- Retinal Tear/Holes with symptoms
when would you do an urgent referral for RD
- RD with poor VA (Macula off) unless this is longstanding retinal hole/tear without
symptoms. - Lattice degeneration with symptom of flashes and floaters
risk factors for RD
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)
what is snail track degeneration
o Characterised by sharply demarcated bands of tightly patched ‘snowflakes’ that give the peripheral retina a white frost-like appearance
what is Cystic retinal tuft
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
what is Zonular traction tuft
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
what is white with pressure
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
what is myopic chorodial atrophy
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
what is wet AMD
abnormal growth of BV
what is dry AMD
DRY AMD = retinal cells die off & are not renewed (because function of RPE is reduced)
o Geographic atrophy = cell death of RPE cells
what is normal (for AMD)
o No signs of AMD
o Small (hard) drusen <63 microns)
what is Early AMD with low risk of progression
o Medium drusen 63-125 microns
o Pigmentary abnormalities
what is Early AMD with medium risk of progression
o Large drusen >125microns
o Reticular drusen
o Medium drusen with pigmentary abnormalities
what is Early AMD with high risk of progression
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
what is late AMD
o Geographical atrophy
o Significant visual loss associated with
dense/confluent drusen
advanced pigmentary changes and/or atrophy
vitelliform lesion
what is seen in late AMD (wet inactive)
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
what is seen in late AMD (wet active)
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
what is seen in late AMD (indeterminate)
o RPE degeneration and dysfunction
o Serious PED without neovascularisation
prevalence of AMD
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
Risk Factors of AMD
- 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
symptoms of dry AMD
gradual reduction (over months-yrs)
bilateral changes
distortion only in advanced cases
symptoms of wet AMD
loss of vision more quickly
unilateral/ one eye worse
severe/ obvious distortion noticed
which layer is affected in dry AMD
sub rpe
which layer is affected in wet AMD
subretinal layer
signs of dry AMD
drusen (hard or soft)
pigmentary changes
eventual development of geographic atrophy
signs of wet AMD
med - large drusen
subretinal or preretinal haemorrhage
CNV
PED
CMO
what is CNV
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
dry AMD tx
- 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
Dry AMD supplements
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.
WET AMD referral
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
Side effects of anti vegf
Side effects include bleeding in the eye, feeling as if there is something in the eye, eyes being red and irritated
o Photodynamic therapy (PDT) for AMD
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
anti VEGF drug used and process
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
contraindications for advising AMD supplements
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
macular hole
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
when would you refer a sub conjunctival haemorrhage
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
what to ask about for sub conj haems
hypertension, medications, acute or chronic cough, eye rubbing, heavy lifting, recent ocular or head trauma, bleeding or clotting abnormalities and recurrent subconjunctival haemorrhage
differential diagnosis of sub conj haemorrhage
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)
what is the difference between pedunculated and sessile papillomas
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
general management for sub conj haem
- 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
differential of ptergium
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
what is pterygium
Benign wing shaped fold of fibrovascular tissue
Degenerative condition usually found in Hot/High UV climates
management of pterygium
- 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.
cause of pinguecula
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
signs of bacterial conjunctivitis
- Lid crusting
- Purulent discharge
- Conjunctival Hyperaemia
- Papillary Reaction
- no corneal involvement usually à if corneal, possibily gonococcal
management of bacterial conjunctivitis
- 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
Contact lens wearers with a diagnosis of bacterial conjunctivitis should be treated with
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
when would bacterial conjunctivitis be referred
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
viral conjunctivits signs
- 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
viral conj management
- 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)
what is disciform keratitis
central or eccentric zone of epithelial oedema overlying stromal thickening
folds in Descemet’s membrane
uveitis
Keratic Precipitates
sings of angle closure glaucoma
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
HZO more likely in who
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)
signs and symptoms of HZO
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
HZK management
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
HSK management
(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
HSK signs and symptoms
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
anterior uveitis signs
- 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)
severity of anterior uveitis grading
- 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.
grading of cells and flare
- 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
what causes cataract
Caused by denaturation of protein fibrils within the lens due to oxidative
stress, increasing age and metabolic disturbance
NS risk factors and signs
- Poorer Diet
- Low socio-economic status
- Age
- Smoking
- Larger Lens
- Higher Ambient Temperature
Signs: - Yellowish hue
- Myopic Shift
cortical risk factors and signss
Cortical – Appearance of spokes
* Sunlight (UVB)
* Lens size
* Age
* Diabetes
* Smoking
* Female
* Non-Caucasian
Signs:
* Increased astigmatism
* Monocular Diplopia
posterior sub cap risk factors and signs
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.
what happens in cataract surgery
- Day case procedure
- Local anaesthetic drops and possibly intra-cameral (into AC) injection
- Small incisions made in the cornea (1-3mm in size)
- Viscoelastic substance injected to maintain shape and pressure in eye
- Capsulorrhexis – round incision made in the anterior capsular bag to get
access to the cataract - Hydrodissection – fluid injected between the capsule and cataract to
separate them - Phacoemulsification - high frequency ultrasound device which breaks the
cataract up into 2-4 small pieces which are then suctioned out - A folded artificial intraocular lens (IOL) is then inserted (via the small
incision) and placed into the capsular bag - Stitches are rarely required due to it being keyhole surgery
cataract surgery risks - said to px
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
complications 48 hrs post catarct surgery
Corneal oedema
o Raised IOP
o Uveitis
o Cystoid macular oedema
o Periocular Bruising,
o Wound leak,
o Wound burn,
o Hyphaema
what is the drainage system
Drainage – through the puncta, through canaliculi, into lacrimal sac to the nose. Pumped into there
from lid action and gravity feed to lower punctum
what is dry eye disease
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.
what are the layers of the tear film?
- lipid layer
- aqueous layer
-mucus layer
what is the role of the lipid layer?
Reduces water evaporation from the aqueous layer
Secreted by: Meibomian gland, glands of Zeiss, glands of Moll.
what is the role of the aqueous layer
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
what is the mucus layer role
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
normal value for schirmers test
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
what is the Phenol thread test
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
tear meniscus height
o G1: >0.3mm
o G2: 0.2 mm
o G3: <0.1mm
what does fluroescein do?
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).
what does lissamine green do
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
differential diagnosis for lumps on eyelids
hordeloum
chalazion
molloscum contagiosum
xanthelasma
papilloma
basal cell carcinoma
squamous cell carcinoma
malignant melanoma
epidermoid cyst
cyst of moll
Adequate production and drainage of the aqueous layer is necessary for the
maintenance of:
- 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).
- moist conditions on the eye surface (evaporation reduces surface temperature)
- 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.
what happens when there is impaired lid function
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
what is Epitheliopathy
An irregular corneal epithelium (due to corneal lesions or keratoconus) can produce a
thin and unstable tear film.
tear substitutes
- 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
Aqueous-deficient (ADDE)
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)
what is Dacryocystitis
Bacterial infection of lacrimal sac – secondary to blockage on the nasolacrimal duct
symptoms and signs of Dacryocystitis
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
college managment guidelines dacryocysitis
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
management of entropion
- 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
management of ectropion
College Management Guidelines – Mild cases require no treatment, tape lid at night to avoid corneal exposure, ocular lubricant
Refer–Severe cases requiring surgery
management of trichiasis
- 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
what is a chalazion
sterile chronic inflammation from a blocked gland
chalazion signs and symptoms
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
whats an external hordeolum
Acute bacterial infection of the lash follicle and its associated gland of zeiss or
moll
whats an internal hordeloum
Acute bacterial infection of the Meibomian gland, usually staphylococcal: can develop into chalazion if untreated.
signs and symptoms of hordeolum
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
management of hordeloum
- 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
what is pre septal cellulitis
Bacterial infection of tissues lying anterior to the orbital septum common in infants
under the age of 10 Caused by Staphylococcal, Streptococcal
what is orbital cellultis
Bacterial infection of the tissues lying posterior to the orbital septum (within the orbit)
severe and life threatening
signs of orbital cellulitis
- Proptosis
- Restriction of EOM
- pain with eye movement
- reduced VA
- reduced CV
- RAPD present
- pyrexia
- fever
-malaise
-unilateral swelling of conj and lids
reasons for fitting RGPs
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
RGP Boston Simplus Multi-Action Solution
Ingredients:
- 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
how to use RGP MPS solution
- Soak lenses in solution for 4 hours or overnight in an empty lens case
- Wash your hands
- After soaking, rub both sides of the lens with 4 drops of the cleaner solution in the
palm of your hand for 20 seconds. - Rinse using the solution for approximately 5 seconds to remove loosened surface
deposits - Insert lenses
- Discard solution 90 days after opening
Boston 2 Step Cleaning and Conditioning System
Ingredients
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
RGP 2 step cleaning and conditioning system
- Wash your hands
- Rub both sides of the lenses carefully with 4 drops of cleaner (Step 1) in the palm
of your hand for 20 seconds - Rinse both sides of the lens with a saline solution
- Soak your lenses for 4 hours with the conditioning solution (step 2)
- Add a drop of conditioner to the lens for extra cushioning and insert into your
eye. - Rinse your lens case with a sterile disinfecting solution and then wipe dry with a
clean tissue. Avoid air-drying.
RGP FITTING what to do when the difference in the Ks is < or equal to 1DC
fit on flattest K (round to 0.05mm)
(plus lenses tend to drop a little, consider fitting 0.05mm steeper)
RGP FITTING what to do when the difference in the Ks is > 1DC
use formula:
BOZR=FlatK - (FlatK-SteepK)/3
RGP fitting why are HVID and VVID measurements taken
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
RGP fitting Pupil diameter indicates what?
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
flat fitting RGP lens
Nafl = central touch, large area of edge lift
Flat fit creates a negative tear lens, resulting in plus over Rx
steep RGP fitting
Nafl = central pooling (smaller area of pooling = steeper lens)
Steep fit creates a positive tear lens resulting in a negative over Rx
RGP lenses what happens when over refraction done or when diameter increased
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
most RGPs are which material
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
the total diameter for RGPs
- 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
what is lag and why do we measure it
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
hydrogel what is it and advnatge and disadvantages?
- 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
silicone hydrogel
- 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
opteyes
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
SCLs: Adjusting rx for BVD: needs to be taken in account for rx
> +/-4.00
K= F/((1-dF))
K = new CL power F = spec power d = BVD (in metres)
SCL specification is written out in the following way:
lens name manufacturer BOZR/TD/rx,
e.g. Bioinfinity coopervision 8.4/14.2/-3.00DS
how to adjust lens when flat fit vs steep fit
Flat fit = steepen by increasing TD or reducing BOZR
Steep fit = flatten by decreasing TD or increasing BOZR
why is pupil size measurement taken for cls
to make sure the optic zone radius covers the pupil at all times.
If pupil size bigger than measured then distortion seen
why is HVID measured
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
linarial cls
spherical +8.00 -12.00DS
toric +8.00 –10.00DS, 2.25DC is the highest
water content 54%
Dk 80
0.4 modulus
precision ones torics
+8.00 -12.00
-2.25DC
Dk 90
51% water content at core
opteyes
+20 -20DS, highest cyl 5.75DC
Dk 128
48% water content
To work out the power required for a certain working distance
1/dist(m) = D
1/0.5m = 2.00D
when px works on screens what is the law for specs from work
- 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
what does the employer need to know from the ST eg VDU users
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
DVLA group 1
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
DVLA group 2
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
driving safety and vision
- 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
for which eye conditions does the DVLA need to be informed?
- 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
which bifocal segment for which rx
o R = PLUS
o D = Minus
aspheric lenses advantages and disadvantages
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
prism thinning for varifocals
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
MAR advantages and disadvantages
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)
Uv400
Blocks UVA & UVB rays up to 400 nanometers. Good for patients with
cataracts & AMD.
Decentration calculation:
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
Levels of Thinning:
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
Cellulose Acetate: Most widely used
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
Cellulose Propionate
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
Polycarbonate
o Primarily used for safety eyewear (the one piece and side shields).
o Can be soft or high impact resistant.
Lenticular Lenses
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
photochromatic lenses
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)
varifocals soft and hard designs
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
High index = reduction in abbe number = increased chromatic aberrations
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)
Crown glass lens advantages and disadvantages
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
CR39 (ophthalmic hard resin) advantages and disadvantages
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
Polycarbonate advantages and disadvantages
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
how is the total power of lens found
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
Optoms/DOs have a responsibility for safety specs
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
VDU users laws
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
polycarbonate should not be cleaned with what
Polycarb shouldn’t be cleaned with acetone or methyl chloride; should avoid extreme heat – not suitable for chemical engineers
Consider glass if molten metal
the employee responsibility for eye protection
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
the employer responsibility for eye protection
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
British/European standards for safety specs
- 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
saftey specs lens markings
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)
saftey specs frame markings
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)
saftey specs order of markings
- 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
welders flash
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
welders flash tx
- 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
Commotio retinae
usually due to blunt force resulting in whitening and opacification of retinal area (pseudo-cherry red spot)
what to do when chemical injury
- Wash out the eye IMMEDIATELY: normal saline or head under a cold water
tap/bucket (eyes open) - After 1 litre of irrigation (15-30 mins), review pain levels
- Instil topical anaesthesia if pain level if high
- Evert the lid and clear the eye of debris
- sweep with cotton bud
- Wait 1 minute, measure pH of tear meniscus (lower lid) – pH 7-8 acceptable
- Continue irrigation if necessary, repeat pH every 5-10 minutes
- Admit to hospital
what is Anisometropia
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
what is anisokonia
For patients with anisometropia of more than 2, they may experience a difference in the
size and shape of visual images and magnification: Aniseikonia.
what problems can be caused with anisometropia?
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
why do problems happens with anisometropia
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
Symptoms of Aniseikonia
- Visual discomfort
- Visual distortion
- Difficulty with stereopsis/BV.
- Dizziness, H/A, Nausea.
Single Vision Dispensing for an Anisometropic Patient
- 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.
vertical differential prism
- 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
spectacle magnification equation
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.
other solutions for Single Vision Dispensing for an Anisometropic Patient
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.
Bi-focal Dispensing for an Anisometropic Patient
- 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
anismetropic px, bifocals different round seg sizes
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)
Franklin Split method Bifocals
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
main problem for anisometropia disp for SV vs BIF
SV - different retinal image sizes
BIF - differential prism
what is image displacement
Is the prismatic effect induced by the combination of the bifocal type and the power of the distance lens rx in the reading position
Varis for anisometropia disp
- 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
seperate SVN disp for anismoetropia
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
how does slab off work for bifocals
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)
which bifocal segment to give for rx types
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)
90D volk field of view and magnification
FOV: 89
Mag: 0.76
superfield volk field of view and magnification
- FOV: 116
- Mag: 0.76
posterior subcapsular grading
o 1+ = 1-2mm
o 2+ = 2-3mm
o 3+ = >3mm
cortical cataract gradings
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
pupils: when does the near response needs checked
near response only checked if direct response is abnormal
what is a partial rapd
Sluggish response / slight dilation = partial RAPD
afferent pathway
Nerve that carries information towards the central nervous system
efferent pathway
Nerve that carries information away from the central nervous system
sphincter muscle
- 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)
dilator muscle
- 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
How does the pupil Dilate in dark lighting?
- The sphincter muscle relaxes
Þ The sphincter muscle has the biggest effect on pupil size - The dilator muscle contracts
How does the pupil constrict in bright lighting?
- The sphincter muscle contracts
The sphincter muscle has the biggest effect on pupil size - The dilator muscle relaxes
pupils what does it mean when there is no direct reflex?
problem anywhere in nerve pathway
pupils when direct response but no consensual response
but no consensual = problem with efferent pathway of consensual eye
RAPD
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
anisocoria
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
Horner’s syndrome
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
Holmes-Adie pupil
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
Argyll Robertson Pupil
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
CN3 Palsy pupils
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
Sympathetic pupil pathway (efferent pathway = brain > eyes), problem then what do we think
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
Parasympathetic pupil pathway (afferent pathway – eye to brain)
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
pupils how to distinguish where the lesion is for parasympatheic branch of the efferent pathway
- 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
parallelopiped - how to do it and set up
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.
specular reflection - how to do it and set up
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
Yellow/Wratten 12 filter
Can be used in addition to the Cobalt blue filter
to enhance contrast.
Red free (green)
Enhances the contrast of blood vessels on the
corneas of contact lens wearers and
haemorrhages seen under the conjunctiva
diffuse illumination
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
optical section
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.)
direct retro illumination
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
indirect retro illumination
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
explanation of cataract
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.
explanation of floaters
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.
explanation of PVD
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.
dry eye explanation
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.
blepharitis explanation
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.
Lid wiper epitheliopathy
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
Post cataract surgery drops
chloramphenicol 0.5% 4x a day for 5 days
Dexamethason 4x a day for 28 days
RGP - when flat fit what power is the tear film so what is the over refraction
flat fit – will have a negative tear film then it would have a plus over refraction
ICON RGP lens water content, DK, rx change, material
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
what are common RGP materials - advantages and disadvantages
Silicone acrylate - more prone to lens flexure
Flurosilicone acrylate- better wetability, fewer deposits, but can be britte if too thin
what wavelength does polarised lenses block
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.
super readers
offers larger intermediate and near reading areas
super soft design
super digital - soft design
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)
definition elect - hard design
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
How often do saftey spec needs replaced
Generally every 2 yrs
Is a lens is scratched for saftey specs - is it still okay to be used?
No
What would you advise a welder in terms of eye protection
A9KG
Each letter and numbers shows meeting standard - resistant to head etc
anti reflection coating
quarter of a wavelength thick
half a wavelength out of sync - cancels the wavelength out
reticular drusen
reticular drusen are above RPE and more yellowish and in a network pattern and are more often extend to periphery than normal drusen
vitelliform lesion
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
