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Year 3 > Exam Questions > Flashcards

Exam Questions Flashcards

1
Q

Describe the design of the ishihara colour vision test

A

Colour confusion test
plates are phedu Isochromatic ( fake 1 colour)
1st plate in every test fake demo
4 Seconds per Plate
not every plate will have Something on it
only finds Red or green defect
in a 28 plate edition 4 wrong = fail

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2
Q

What lightening should be used to illuminate the ishihara test

A

daylight source of colour temperature 6500k tungsten no good

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3
Q

when using the Ishihara Colour vision test. what is the recommended working distance?

A

7 5 cm

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4
Q

Explain the meaning of the following terms related to colour vision
Dueteranomaly
Protanopia
Rod Monochromacy

A

-Deoteranormaly - Green definecy appears grey

Protanopia - Red definecy

Rod Monochromacy- only one photo pigment works.

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5
Q

what is the most Common type of congenital colour vision defect

A

red and green more common in males than in females
deuteranomaly
anomalous trichromacy

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6
Q

State 2 causes of aquired color vision defect(10)

A

Congenital - inherited photo pigments abnormalities
excessive use of therapeutic drugs
disease or Injury that damage optic neve

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7
Q

give 2 ways in which acquired colour vision defects may differ from Congenital defects

A

aquired - develops to Ocular Conditions- or Side effects of medications or toxic effects of Chemicals,trauma aging

Congenital - Inherited at birth In curable and do not Change

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8
Q

Define the terms depth perception and Stereopsis (10)

A

Death perception ~ visual ability to Perceive the world In 3D

Stereopsis - Perception of depth produced by the reception in the brain of usual Stimuli from both eyes In Combination

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9
Q

A monocular subject may use the following clues to experience depth perception
overlapping Geometric perspective Relative size Aerial perspective Parallax
In one Sentence give brief definition of each of these clues (25)

A

Overlapping - the object in the background obscured by objects in foreground Seem further Away
Geometric . parallel lines narrowing gues perception of been further Away
relative give . objects further away Seem to be smaller
Aerial - further away less contrast
Parallax - determine distance doe to Speed Something is travelling Slower Seems to be further Away

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10
Q

what range of values would be considered to be normal for stereoacuity

A

.20 - 40 Sec’s of Arc

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11
Q

How is stereoacuity affected by
Pupil distance
Amblyopia

A

PD - larger PD = better SA

Amblyopia - worse SA

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12
Q

Define Presbyopia (15)

A

loss of elasticity of the lens
loss of eyes ability to focus on near objects
starts to happen from age 40 +

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13
Q

state 2 changes that Occur within the eye that contribute to Presbyopia (10)

A
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14
Q

show on a diagram how amplitude of accommodation varies with age (20)

A

13 D at 13 years of age then less 0.25D Per year

Amp = 18 - ( 1/3 Patients age)

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15
Q

what’s meant by the term depth of field (10)

A

Distance between nearest and farthest objects that arein Sharp focus In an image

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16
Q

How does depth of field affect the value of the amplitude of accommodation as measured using the push- up method (5)

A

Increases

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17
Q

A Subject with a -1.00D of myopia has anamplitude of accommodation of +1.50D. what is the Power of the lens (to the nearest 0.25D) that would be required for close Work at 36cm (20)

A
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18
Q

Explain how astigmatism may be classified according to the positionof the focal lines formed by a distant Point object relative to the retina (25)

A

Simple Myopia 1 line on retina other in front
Simple Hyperopia 1 line on retina 1 line behind
compound Myopia both line in front
Compound Hypermyopia both behind
mixed 1 Infront 1behind

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19
Q

LV
compare the practical advantages and disadvantages of mounted Spectacles magnifiers + monocular Near vision Spectacles Telescopes include 4 points

A

spec Mounted telescopes Can provide longer working distance, Can provide higher amount of magnification
can be variable focus
have significantly restricted foV
easie to provide illumination to object for spec mounted telescopes

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20
Q

State criteria for registration as Sight impaired

A

3/60 → 6/60 full visual field
6/60→ 6/24 moderate field loss
6/18 or better + gross field defect

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21
Q

Explain what is meant by the terms
Myopia
Axial Hypermetropia
far point

A

myopia- light from a distant object is focused in front of the macula of an unaccommodated, uncorrected eye
Axial - the Power of the reduced Surface is standard while the axial length is Shorter than +22.22mm light from a distant object is focused behind the macula of an un accommodated,uncorrected eye
far point - the Point Conjugate by refraction with the macula of the uncorrected unaccommodated eye

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22
Q

A Patient has Snellen acuity of 6/36 explain what this fraction represents

A 
6= testing distance
36 = Distance at which smallest letter CX can read Subtends 5' of Arc
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23
Q

What would 6/ 36 be as decimal

A

6/36 = 0. 16667

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24
Q

explain log Mar

A

logarithmic value of minimum angle of resolution in minutes

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25
Q

logmar acuity of 0.0 What Snellan acuity does this represent

A

6/6

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26
Q

3 advantages in using baily lovie chart Instead of a Snellen chart

A

equal number of letters on each line
works @ different working Distances still acurate each gaps different when going down chart
consistant 0.1 log until progression in letter height between rows
letter Spacing= letter height - reduce visual Crowding

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27
Q

Define near point and amplitude of accommodation

A

near point - Conjugate with the macular by refraction at the fully accommodated uncorrected eye (b)
Amp Of acc the maximum accomodation the eye can exert
amp = k-B

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28
Q

State 2 advantages applying to all prescriptions of contact lenses over spectacles

A 
cosmetic
Improved fov
no magnification 
Sports 
Sunglass choice
less aberrations
no prismatic effect
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29
Q

State 2 Specific Conditions in which C L may be used for therapeutic reasons

A

Keratoconus - Improve VA through Corneal Surface +tear layer
Albinism - coloured CL reduces blordisc and photophobia
ectropian- bandage CL
High myopia - Reduction in Spectacle magnification

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30
Q

Briefly describe a typical Problem which a new wearer of RGP might experience during adaption
What advice
Problem- Discomfort due to lens and lid interaction

A

Problem- eyelids will touch lens when blinking
advice - increase Wear time slowly
if noticable look down for a few moments
use conditioning Solution to help with wetting

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31
Q

briefly describe shape of Cornea

A

oval in shape average measurements are 11mm horizontally
10mm vertically
radi average 8 - 8.5

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32
Q

explain terms edge lift when applied to RGP including reason for its presence

A

the final curve I’on the back surface of the contact lens is slightly flatter this Is to aid tear exchange + helps lens removal

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33
Q

name 2 preservaies currently used in RGP CL Soaking Solutions

A

Polyhexanide
Hydrogen peroxide
EDTA

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34
Q

list instructions which you would give to a CX when advising Safe removal of RGP lens which has moved onto the Superior bulbar Conjunctiva

A

wash+ Dry hands
look into mirror
Carefully reposition the CL onto Cornea through the eyelid

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35
Q

State 1 typical diameter of Scleral contact lens

A

21-25mm

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36
Q

State 1 typical diameter of f rigid contact lens

A

8.5-10.5mm

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37
Q

State 1 typical diameter of a soft contact lens

A

13.5 - 14.5mm

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38
Q

How does the BOZR of a rigid contact lens usually relate to the Central radius of curvature (k reading) of the cornea

A

The BOZR of an RGP Contact lens is the Same as the flattest k reading

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39
Q

How does the BOZR of a soft contact lens usually relate to the Central radius of curvature (k reading) of the cornea /

A

The BOZR of a soft cL is 0.8mm - 1mm flatter than the flattest K reading

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40
Q

State 1 typical K reading

A

8.00mm

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41
Q

State 2 advantages of rigid gas permable contact lenses over traditional (non - Silicone) soft contact lenses (30marks)

A 
Improved VA
Good for astigmatism VA  + fit
Improved hygiene
myopia control 
Greater amounts of Oxygen
High Rx range
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42
Q

list signs which maybe present in Someone who is suspected of having a microbial Keratitis

A 
Signs
closed eye
Swollen eyelids
Hyperaemia
Lacimation
Reduced VA
wearing Sunnies + Photophobia
corneal staining (SIit lamp)
Central corneal ulcer ( Slit lamp)
Anterior chamber Involvement
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43
Q

list Symptoms which maybe present in Someone who is suspected of having a microbial Keratitis
(40 marks fo Signs + Symptoms )

A 
Symptoms
pain
Sudden onset Possibly on lens removal
Red eye
lacrimation
Poor vision
Photophobia
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44
Q

name a bacterium which is a common cause of microbial Keratitis

A

Staphylococcus aureus, pseudomonas aeruginosa

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45
Q

name a Virus which is a common cause of microbial Keratitis

A

Herpes Simplex
Zoster
adenovirus

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46
Q

name a fungus which is a common cause of microbial Keratitis

A

canidida Albicans

fusarium solani

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47
Q

name a protozoa which is a common cause of microbial Keratitis

A

Acanthamoeba

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48
Q

A contact lens wearer who appears to be displaying Signs + Symptoms for Keratitis
You are alone in practice
Describe course of action which you should take (40 marks)

A

Any painful + redeye should cease CL wear immediately but keep Cl in case as made need to determine cause

As a Do I would contact local opticians to try get CX in to See optom or clo if not - refer to local eye hospital Or A + E,would contact them ahead to make aware to expect cx,give referral letter with main details on
and include
Relevant history + Symptoms
Signs 
VA On the day
Take CL + case to hes
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49
Q

Name the document which a Prospective wearer must possess before anyone can commence a contact lens fitting Include 3 Criteria which this document must satisfy (40 mark)

A

the Eye Exam findings/ Prescription / Statement
Signed and in date (2 Years)
Patient details

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50
Q

state 2 advantages of scleral contact lenses over rigid Corneal contact lenses (40 marks)

A

Good for therapeutic fitting
can be used for instilling drugs
High Rx range

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51
Q

in traditional non Silicone Soft contact lenses

What is the main advantage of a high water Content material over a low water content material

A

Increases the amount of oxygen which reaches the Cornea
Improved comfort
easier to handle

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52
Q

state 1 disadvantage of a high water content material (30 marks)

A

can dry out more than lower water content lenses

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53
Q

name + describe two findings which might be recorded at an aftercare appointment following slit lamp examination (40 marks)

A

tear breakup time
Comeal and Conjunctival Staining
R GP lens fitting

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54
Q

State 2 reasons for the use of the Keratometer at a routine aftercare appointment (30 marks)

A

check for Pathological Conditions
check non - Invasive tear break up time
check Corneal Integrity

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55
Q

list 2 other elements of a routine contact lens after care (30 marks)

A 
History and Symptoms
contact lens compliance
check vision + VA + over refraction
check lens fitting + lens condition
check Spectacle visual Acuity
feedback + Future actions
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56
Q

Briefly describe the condition keratoconus (30 marks)

A

A collagen disorder of the Cornea
the Cornea thins and is displaced down and in from the Central position
the Cornea is distorted + Cone shape
onset is usually lateteens to early 20 ‘s

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57
Q

Describe an advantage,Specific to keratoconus of contact lenses over Spectacles and explainthe reason behind this advantage (30 marks)

A

contact lens give improved vision as the tear film can be used to correct the astigmatism and provide a Smooth refracting Surface

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58
Q

list 4 designs of CL that could be used in Keratoconus (40 marks)

A

Scleral C L
RGP
Hybrid CL
Piggy back

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59
Q

A man visits your practice with a red,Painful watery RE.He tells you that his eye Suddenly felt uncomfortable yesterday when he was walking in windy conditions,whilst wearing his RGP CL
state 2 Possible causes of his discomfort ( 30 marks)

A 
foreign body (Corneal abrasion) Discomfort,lacrimation 
Microbial Keratitis - pain photophobia reduced VA

alone in practice cause for action
Remove cl ( keep +case)
Go to A + E
Record actions and advice

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60
Q

Describe 4 main advantages of RGP comeal lenses compared to Silicone hydrogel Soft lens

A 
improved VA
Corneal astigmatism Corrected with Spherical lens
fewer deposits
myopia Control
more oxygen
High Rx range 
less allergic reactions
can be modified
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61
Q

Describe 1 advantage of modern RGP materials when Compared to the older PMMA material

A

improved oxygen transmission

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62
Q

Describe one disadvantage of modem RGP materials over pmma (15)

A

lenses are not as comfortable

more likely to break/damage

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63
Q

state 1 typical diameter of a Cornea (HVID) (15)

A

11 mm

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64
Q

for the cornea above (11mm) what would be a typical total diameter for Corneal RGP lens
Soft lens
Scleral lens

A

RGP = 9. 5mm
Soft . = 14.2mm
scleral = 22mm

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65
Q

according to uk legislation List 4 c lasses of Professionals who may legally fit contact lenses (20 marks)

A

Registered medical Practitioner
Registered optometrist
DO who holds an approved qualification and is registered on GOC
Trainee CLO or pre reg optometrist Under Supervision

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66
Q

if a patient is not from your practice requests contact lenses.what document must the Patient show you before you may supply lenses ?
include 3 items of info which must be contained in this document (40 marks)

A

contact lens Specification
Date fitting commenced
Date specification Expires
Patients details ( DOB if under 16)
Practice details
CL details from which CL can be replicated
Pr actioner details and registration number

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67
Q

give 2 examples of important information that fluorescein Sodium Can provide during on initial Contact lens assessment (30 marks)

A

check for Corneal Integrity and damaged cells
check for dry eye
tear breakup time
conjunctival Staining

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68
Q

name a Common finding which might be seen and noted after in stilling fluorescien at initial CL assement (30 marks)

A

Tear quality - Instill fluorescein - Ask Cx to blink count how many Seconds forthe tear film to start to break up
Record this as TBUT

corneal Staining - fluorescein stains any dry or damaged cells
This can range from dryness to a mechanical stain from CL wear ( previous wearer) Any Cornealdamage needs to be clear before CL fitting can Commence

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69
Q

name 4 Structures which are examined with the slit lamp during an Initial CL assesment ( 40 Marks)

A 
Cornea epithelium,Stroma,endothium
Conjunctiva - Bulbar,limbal,Palpebral and tarsal
Lids + lashes
limbal blood Vessels
Tear film
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70
Q

List the advantages a patient with microphthalmos is likely to experience if they were fitted with contact lenses for distance compared to wearing spectacles include 4 advantages (20 marks)

A

increased field of view
reduced weight
fewer aberrations
reduced reflection

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71
Q

describe the symbol cane explain the purpose of this cane and describe how it is used by a visual impaired patient

A

foldable white cane indicates px is visually impaired extends cane and holds diagonally across body or keeps folded and holds across chest

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72
Q

state the defination of severely sight impaired as laid down by the national assistnce act (1948)

A

so blind as to be unable to perform any work for which eyesight is essential

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73
Q

what non optical aid can you advise to help a patient make a cup of tea safely. Describe this aid and explain how this aid works

A

Liquid level indicator
has 3 prongs hangs over edge of cup
middle prong shorter
when water hits prongs device will make noise and vibrate patient can add milk middle prong will activate once touches liquid

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74
Q

if a patient consents to having their name entered onto the register for severely sight impaired. what will happen next within the registration process

A

assesment of needs will be undertaken

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75
Q

3 advantages of spectacle magnifiers

A

hands free
larger field of view
not too expensive
psycholically more acceptable

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76
Q

explain how a telescope can be used to increase their Field of view for a patient with peripheral visual field loss

A

Reverse Galilean telescope

minifies image so remains on central part of retina

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77
Q

what does the pelli-robson chart measure

A

measures contrast sensitivity

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78
Q

name a non optical aid that may assist a patient seeing the dials on their cooker

A

enlarger numbers stickers or bumps ons

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79
Q

which is the form currently used in Britain to certify someone as serverly sight impaired

A

RVI form certificate of vision impairment

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80
Q

after certification of the patient list who recieves copies of the form

A

GP
Local Authority
college of optometrists

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81
Q

differentiate between a symbol cane and a long cane by stating the use of each

A

symbol cane used to indicate person has a visual impairment

long cane used for mobility

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82
Q

explain the term terrestrial telescope

A

/an astronomical telescope withan erector system

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83
Q

explain the term reading cap

A

positive lens placed in front of the telescope objective to adapt it for use with a near object

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84
Q

explain the term telemicroscope

A

A telescopic unit designed to view objects closer than infinity

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85
Q

explain visual field

A

the area in space that can be seen when fixating on a point

86
Q 
state if the following patients would be eligible to be certified  as sight impaired. serverely sight impaired or not eligible for certification
Patient with 
Va 3/60 full visual field
VA 1/60
diagnosed with early AMD with VA of 6/18
A

sight impaired
severely sight impaired
not eligible

87
Q

why can the measurement from the pelli-robson chart be considered more useful than snellan chart for the practitioner assessing the low vision patient (15)

A

snellan chart measures in high contrast and most LV patients have greater difficulty in low contrast. Pelli- robson assesses visual function in real life situation rather than black and white of sight test assesses effect of contrast and likely success with aids

88
Q

Distinguish between heterophoria and hetertropia

A

Heterophoria- in normal binocular vision with both eye fixating there is no deviation. If 1 eye occluded or binocular vision prevented then 1 eye will deviate

Heterotropia- one eye will alwyas deviate. The 2 visual axis are never directed in the same place

89
Q 
with reference to heterotropia, explain the meaning of the follwoing terms
convergent 
divergent 
unilateral
alternating
A

Convergent -1 visula axis rotates nasally compared to the other axis
Divergent- 1 visual axis rotates outwards compared to other eye
unilateral- the deviation is always in the same eye
alternating- can switch/ change between each eye either eye can take up fixation

90
Q

concomitant
incomitant
constant
intermittent

A

concomitant- when angle between 2 visul axis remains the same when viweing distance & near objects what ever position
incomitant- angle between 2 visual axis is compared to object distance position
constant- amount of deviation there all the time
intermittent- comes and goes under certain circumstances

91
Q

what is meant by
dissociated
associated heterophoria

A

dissociated- 2 eyes presented with completly diff targets so that fusion reflex is presented
associated- the amount of phoria meassured usinga test in which part of the image is the same for both eyes (mallet unit)

92
Q

explain the stage depression of loss model. include a minimum of 4 facts

A

lack of engaement with professional
feelings of worthlessness
poor memory of interaction
feelings of hopelessness of outcome

93
Q

how will patients age influence the sucessful use of a low vision aid (4 facts)

A

less likely to accept
dexerity issues
more likely to have additional needs/health issues
difficult to learn new skills

94
Q

what is the benefit of testing contrast sensitivity

A

(5marks answer) gages visual performance in real world

(15 mark answe)- allows us to predict the likely sucess of LVA’s allows us to gage weather contrast advise is warrented

95
Q

describe the structure of pelli-robson chart

A 
8 rows
6 letters per row
in groups of 3
letters same size 
each triplet has different contrast
varis from 89% - 0.5%
use at 1m
use in good lightling 
progress is logerithmic
96
Q

other things to take into consideration other than visual Field and vA maybe to be registered as sight impaired

A 
impact on life 
home situation
other additional needs
Age of onset
emotional state
physical ability
97
Q

the patient is suffering from visual hallucinations. what is name of syndrome

A

charles bonnet

98
Q

explain what is meant by the terms
myopia
axial hypermetropia
far point

A

Myopia- light from a distant object is focused in front of the macula an unaccommodated, uncorrected eye
axial hypermetropia- the power of the reduced surface is standard while the axial length is shorter than +22.22mm. Light from a distant object is focused behind the macula of an unaccommodated, uncorrected eye
far point -the point conjugate by refraction with the macula of the uncorrected unaccommodated eye

99
Q

describe key features of a landolt ring

A

attends 5’ of arc at specified distance

presented to cx with gap at different positions

100
Q

describe how a landolt ring used in practice

A

minimum angle between 2 objects so eye can resolve as seperate
move away from cx until no gap can be seen
move towards until gap detected
measure distance from cx to landolt C + size of gap

MAR =tan-1 (size of gap/distance to patient)
x by 60 to get minutes of ARC

101
Q

an eye has an ocular ametropia of -1.00 and the nearest object that it is able to focus on is at 25cm from the reduced surface. What is the amplitude of accomodation of this eye

A

K=-1.00D
b=-25cm
AMp= k-B
B=n/b = 100/25= -4.00D
AMP = K-B = -1.00- -4.00= +3.00D amps of accommodation
caluculate the range of clear vision of the eye?

k= n/K   = 100/-1.00=-100cm 
range = -25cm to -100cm
102
Q

Give defininitions of the terms emmetropia and ametropia

A

Emmetropia - An unaccommodated, uncorrected eye will focus distant light ion the macula- far point lies at infinity and in conjugate with the macula

Ametropia - An uncorrected, unaccommodated ametropic eye will not focus distance light on the macula- eyes far point is not at infinity - some degree of refractive error

103
Q

calculate the power of the lens placed at 12mm required to correct an axially ametropic reduced eye with an axial length of +20.83 (30Marks)

A

K’= 4/3 x1000 / 20.83= +64.01D

K=K’-Fe = +64.01 - (+60.00) = +4.01D

FSP = k/1+dK = 4.01/ 1+(0.012 x 4.01) = +3.83D

104
Q

Define spectacle magnification

A

spectacle magnification is the magnification of the retinal image due to the spectacle lens

SM= height of retinal image in corrected ameetropic eye/
Height of retinal image in uncorrected ametroipc eye

=hc/hu’

105
Q

a subject with a refractive ametropia of +10.00D is corrected for distnce vision by +9.00D. Assuming that it is a thin lens. What spectacle magnification does it produce

A

SM=hc/hu’

= +10.00/+9.00 = 1.11

106
Q

The corrected eye in previous question view a distant object subtending 2 degrees calculate the size of the retinal image

A

K=+9.00
K’= +60.00

-1000 tan w /K’

= -1000tan(2)/60 = -0.58

hc’=hu’xSM = -0.58 x 1.11= -0.65

107
Q

Define the terms orthphoria, heterophoria and hetertropia

A

Orthophoria= straight state eyes are in ideal position for distance and near objects -visual axes always remain directed towards fixation object even whe eyes dissociated

Heterophoria- other state-the visual axes are directed towards the fixation object when the eyes are associated but deviate when dissocaited

hetertropia - manifest squint- only the visual axis of the eye that can fixate will pass throughthe object of regard deviation always present angle can vary

108
Q

A heterphoria can be described as uncompensated what does this mean

A

where the eyes are unable to align properly - causes strain on muscles as causes cx to correct over correct,compensate for misalignment

109
Q

explain what is meant by fixation disparity

A

Twinned single oints on the retina are too simplistic. The retina has elliptical zones and if the images falls within these then there will be no diplopia

110
Q

Why is it necessary to dertermine Weather a hetertropia is concomitnat or non concomitant? (10Marks)

A

concomitant means the angle between visual axis are the same , incomitant varis with direction of gaze.

111
Q

state 2 forms of treatment that maybe used in heterotropia

A
112
Q

mildest colour defect

A

Anomalous trichromacy all 3 photopigments are present but one is less sensitive

113
Q

How is stereoacuity affected by
interpupillary distance
Amblyopia

A 
PD = longer PD = better Stereo acuity 
Amblyopia = Worse Stereoacuity
114
Q

Give definition for snellan acuity and Minimum angle of resolution (MAR) (20marks)

A

snellan based a chart around letter recognition as opposed to resolving gratings. Letter decreased in height allowing the patient to remain seated in a test room tested at 6m as eyes natural depth of field can over come this

The angle (meaursed in minutes of arc) subtended at the nodal point of the eye by 2 points which can just be distinguished as seperate

115
Q

what is the height of a 12m snellan letter

A

tan5’ = letter height/ letter size therefore
letter height = tan5’ x letter size

=tan0’5’ x 12 x 1000 (mm) = 17.45mm

116
Q

what is the purpose of an optometer

A

To measure ametropia . device that measures refractive error

117
Q

explain the difference between a subjective optometer and an objective optometer

A

Subjective - Determines refractive error by analysing response from the patient ( eg Snellan)
objective - no response - (eg Autorefractor/ ret )

118
Q

Name 3 signs of diabetic retinopathy

A 
retinal haemorrhages
hard exudates
retinal oedema 
neovasucularisation
cotton wool spots
microaneuysm
venous dilation
119
Q

State 3 disadvantage of spectacle magnifiers

A

short WD
thickness
increased TCA
Problems with illumination

120
Q

state 3 advantages of spectacle magnifiers

A

better FOV than telscopes
Hands free
look normal

121
Q

define term low vision

A

THe WHO defines low vision as visual acutity less than 6/18 and blindness as visual acuity less than 3/60 or visual field < 10 degrees

122
Q

state the definition of serverly sight impaired as laid down by the National Assistance Act (1948)

A

Blind so blind to be unable to perform any work for which eyesight is essential

Partially sighted there is no legal defination of partial sight provided by the act gives guidance of- Substantially and permanently handicapped by defective vision caused by congenital defect or illness or injury

123
Q

6 psychological stages a cx may go through when recently diagnosed with sight loss

A 
depression
shock
realistic acceptance
denial
disbelief
Anxiety
anger
124
Q

What is the pathological term used for the absense of the iris

A

Aniridia

125
Q

What is the pathological term used for when the eyeball is abnormally small?

A

Microphthalmia

126
Q

short notes

Keratoconus (5 facts) (30 Marks)

A

Cornea cone shape
thinning of the cornea causes it to buldge into a cone shape
more common in males late teens to early 20’s
can occur in one or both eyes
can caused blurred vision due to astigmatism

127
Q

write short notes iris coloboma (5facts 30marks)

A 
occurs at birth part of the eye does not fully develop
can cause light sensitivity 
can affecrt one or both eyes 
iris looks like a key hole shape 
does not affect vision
128
Q

shorts notes on albinism (5 facts 30 marks)

A 
lack of pigment in the iris 
photophobia 
nystagmus
reduced VA due to development of retina 
poor depth perception 
abnomal curvature of eye causing astigmatism
129
Q

A device intended to be postioned and supported by the users hand and without artifical support

A

hand magnifier

130
Q

A magnifier in which the support is designed to position the optical system at a set or adjustable distance from the object to be viewed

A

stand magnifier

131
Q

The distance from the magnifier surface nearest to the eye to the virtual image when the object is placed at teh designated position

A

exit image vergence

132
Q

Agreed distance of 250mm between the anterior corneal vertex of the eye and the object observed

A

Reference seeing distance

133
Q

Telescope mounted in or on a spectacle frame

A

Spectacle mounted telescope

134
Q

An astronomical telescope to which has been added an erecting system

A

Terrestrial telescope

135
Q

A Positive lens placed in front of a telcope objective to adapt the device for viewing a near object

A

Reading Cap

136
Q

A negative lens placed in front of a near vision telescope/ telemicroscope objective to adapt the device for viewing distance object

A

Distance cap

137
Q

Distance between the most anterior portion of a near-vision telescope/ telemicroscope and the object

A

free working distance

138
Q

Device used by visually impaired persons to enhance vision

A

Low vision aid

139
Q

state why the patient may suffer from asthenopia after prolonged use of the aid

A

Light is divergent when reaching the eye some accommodation will be required at an elderly age not much accommodation for prolonged periods of time

solve problem - cx to wera SVN specs

140
Q

stand magnifiers may have various sources of power for internal illumination. Name 2 such power sources and name 2 such light sources. Name the most efficient light source currently available

A

Power sources- mains batteries rechargeable batteries
light sourses tungsten bulbs, halgen, fluorescent, LED
Most efficient - LED

141
Q

List disadvantages of the Snellan chart for Low vision 6 facts (30 marks)

A 
too few letters at lower acuties 
non logrithmic design
no constant ratio between size of letters
non consistant spacing = crowding
not real life enviroments 
designed for use at 6 metres 
measures high contrast only
142
Q

advantages of bailey lovie chart for assesment of low vision chart

A 
logarithmic in design 
constant ratio of letter size
line and spacing equal throughout 
can be used at any WD 
allows more accurate prediction of mag requirements
each line has 5 letters
143
Q

Why is the measurement of contrast sensitivity considered useful in the assement of low vision patient

A

measures in real life situation assesses likely success of visual aids

144
Q

compare the practical advantages and disadvantages of monocular Spectacles Magnifiers + Monocular Near vision Spectacles telescopes

A

Spec mounted telescopes can provide longer working distance
Spec mounted telescope can provide higher amount of magnification
can be variable focus
have significantly restricted f. O.V
easier to provide illumination to object for Spec mounted telescopes

145
Q

Badal Optometer

A

A Single high powered len’s around 16.00D
The lens is positioned So that he Second focal Point coincides with the plane of Spectacle lens which therefore measures Spectacle Prescription
one eye occluded the target is moved towards the Patient Until retinal Image appears clear

146
Q

Scheiner Disc

A

opaque disc
38mm in diameter
2 Pinholes around 0.75mm- 1mm-
2-3mm Apart

147
Q

what is meant by dissociated and associated

A

dissociated - 2 eyes Presented with completely different targets So that fosion reflex is presented
Associated - the amount of phoria measured using a test In which part of the image Is the same for both eyes ( mallet unit)

148
Q

What is keratometry

A

measurereal - of radi of Curvature of the central Portion of the anterior surface of the Cornea

149
Q

what is keratoscopy

A

examination of the shape of the corneal surface

150
Q

Section C

give a definition of Relative Spectacle magnification

A

Is the ratio of the retinal Image size in corrected ametropic eye Compared with retinal Image Size

151
Q

.what is meant - when a keratometer Is described as being a one Position instrument

A

Single Mire
uses 2 doubling Prisms Opposed to are another
can read both principal Median from one Position

152
Q

Explain the difference between anisometropia and anti metropia

A

anisometropia unequal refractive errors in two eyes

antimetropia opposite refractive errors

153
Q

what is meant by Indentation tonometry

A

measures the depth of corneal Indentation made by a Small plunger carrying a known weight.the higher the Iop the harder it is to push against and Indent Cornea

154
Q

give definitions of Scotoma and hemianopia

A

Scotoma - blind spot or partial loss of vision

hemianopia - blindness over half the field of vision

155
Q

a subject with re fractive Ametropia of + 6.50 D Is Corrected for distance Vision by + 6.00D.Assuming that this lens is thin.What Would Spec magnification Produce

A

6.50 / 6.00 = 1.0833
View distance object a 2 degrees - calculate Retinal image size
hu’ = - 1000 tan w / k ‘ =
-1000 tan 2 / 60.00 = -0.58
hc’ = hu’ x Sm= - 0.58 X 1. 0833 = -0.630

156
Q

.How is the field of view affected by a Patients Myopia when examining the fundus using
Direct Ophthalmoscopy
indirect ophthalmoscopy

A

Direct - Reduced

indirect - Unaffected

157
Q

define term Stereopsis

limit of Stereopsis

A

the perception of depth Produced by the reception in the brain of visual stimuli from both eyes

158
Q

What range is normal for stereoacuity

A

2 - 40 Seconds of arc

159
Q

what is the name of the early Colour Vision theory which states that there are 3 types of retinal receptor each responding to a different region ofthe Visible Spectrum

A

Trichromatic theory

160
Q

name a test that can be used to determine Whether a Patients heterotropla is Comitent or Incomitant

A

mobility test or Hess Screen

161
Q

accommodative esotropia meaning + treatment

A

is an Inward turn of one or both eyes can happen when child longsighted - they over focus
Prescribe glasses - helps eyes relax

162
Q

Explain what is meant by refractive Surgery

A

Surgery to the eye to alter the patients refractive error

163
Q

explain
version
Vergence

A

versions- conjugate Movement.the eyes move together binocularly and angles between the visual axis is constant

Vergences - Disjunctive Movements . eyes move in opposite directions

164
Q

Grades of binocular vision

A

Simultaneous Perception lowest
fusion
Stereopsis

164
Q

3 Types of Diplopia

A

Pathological
physiological
Prism Induced

165
Q

simple optometer

A 
consists of a sliding target 
and a high Positive lens
mounted on a rod that's marked with Spec refraction
eye placed at required Vertex distance
relies or Image clarity
166
Q

Disadvantages of Simple optometer

A

/ difficult to determine astigmatism
–non linear
Proximal accommodation will under correct hypermetropia and over Correct Myopia
retinal Image size varis

167
Q

a maddox Rod placed in front ofthe left eye to be used to detect whether a Subject has exophoria or esophoria
What would be the the axis direction of the maddox Rod

A

Horizontal

168
Q

if the left eye is looking through the Maddox Rod what would be used as a target for the right eye

A

Distance Spotlight

169
Q

maddox Rod

In order to determine what type of heterophoria is present what question would the subject be asked

A

Is the line Image on the right or left

170
Q

maddox Rod

what answer would the subject give if exophoria were present

A

line is on the right

171
Q

Prisms can be used with the Maddox Rod to Measure the exophoria
what would the Subject see when the Correct Image is in place

A

the Spot and the line would be together

172
Q

what would be the direction of the Prism used to measure the Exophoria

A

Base in

173
Q

A heterophoria maybe described as Uncompensated what does this mean

A

Symptoms arise when fusion amplitudes are Inadequate to control deviation
muscular fatigue
eye strain

174
Q

Push up method

A

using an RAF Rule
move the Slider for away from CX
instruct (x you will Slowly more Slider toward them along rule
at Some point the text will become blurry
when this happens they need to advise and you stop moving the Role
Read Position of the Slider on the Side of the ruler in distance/ dioptres
Repeat for other eye

175
Q

explain what is meant by Convergence when related to eye movements

A

Aligns the visual axes with the object So two Images will fall on Corresponding retinal points

176
Q

Define near point convergence

A

nearest point for which a subject can Converge whilst keeping Image on the fovea

177
Q

A Subject with a PD of 66mom Views an object on the midline between the two eyes at a distance of 35cm from the Centres of rotation.calculate the Convergence required by each eye In Prism Dioptres

A

1/2 PD XMA

ma = 1/d = 1/ 3.5 = 0.28 X 33 = 9.43 Prism each eye

178
Q

homonymous
hemianopia
heteronymous hemianopia
congruous

A

homonymous -Same
hemianopia -1/2 visual field loss
heteronymous hemianopia- left or right of both eyes
congruous- Same in each eye

179
Q

fixation disparity

A

defined as the difference between the target vergence angle and ocular Convergence angle during binocular fixation

180
Q

indirect ophthalmoscopy

A

exon of the inside of the back of the eye using a beam of light and hand held lens - gives wider view of inside the eye

181
Q

f acultative hypermetropia
manifest hypermetropia
which of these is equal to the amplitude of accomodation

A

facultative- can not overcome by accomodation

manifest Cannot be overcome by accomodation

182
Q

accommodative esotropia

A

is an Inward turn of oneor both eyes that can happen when a Child is longsighted

183
Q

nystagmus

A

an involuntary rhythmic side to Side up+ down or Circular motion of the eye
Contact lens would move with the eye causing less distortion

184
Q

Percervative In RGP lens

A

Polyhexamide

185
Q

Define the terms near point and amplitude of accommodation

A

near point / The vergence required at the fully accomodated eye to form a clear retinal Image
AOA - maximum amount of accomodation an eye can exert

186
Q

An eye has a Ocular Ametropia of -1.00D andthe nearest object that it is able to focus on is a 25cm from the reduced surface
What is the amplitude of accommodation

A

( 25cm - True near point )
Amp = K-B
B= n/ b = 100 / -25 = -4.00D
= - 1.00- -4.00 = + 3.00D

187
Q

Keratometry
fixed doubling
variable doubling

A

fixed doubling- Power of prism is fixed

variable doubling- only one fixed object - Power /position of prism changes

188
Q

placido disc

A

Corneal topography examines the weall shape of the cornea and is useful when more complex lenses are required
the simplest tool is the placido disc
it is made up of a Series of Concentric black and while circles with a sight hole in the centre
KeratoScope

189
Q

3 advantages of a non- contact method of tonometry

A

eliminates Corneal contact
eliminates Risk of infection
Does not need topical anesthesia

190
Q

Definition of relative Spec Magnification

A

the ratio of the retinal . image Size in the corrected aretropic eye compared with the retinal Image size in the Standard Emmetropic eye

191
Q

list 5 ocular Structures

A 
lids + lashes - bletharitis - Smooth eyes
Cornea -
conjunctiva - smooth eyelids
Anterior chamber - blood cells
Iris - melanomia-
Limbus - Redness
192
Q

Explain Inverse Square law

A

illuminance at a point on a Surface Perpendicular to a Source is In versely Proportional to the Surface of the distance from Source to Surface
E= I/ d2

193
Q

cosine Square law

A

illuminance of a surface varies as the Cosine angle of Incidence
the greater the angle the Lower Illumination falling on Surface
E = I / d2 x cos ( angle)

194
Q

luminous flux

A

rate of light flow from the Source in a given direction

195
Q

illuminance

A

the amount of luminous flux falling on a surface
Symbol E
unit lux

196
Q

Reflectance

A

A Ratio comparing the lomens of a flux leaving a surface to the lumens of a flox that were incident on the surface

197
Q

Dry AMD

A 
loss of central vision
3 stages early Intermediate,late
no treatment for late
certain medication may slow process
may struggle to See peoples faces
Colours are less bright
regular check ups
monitored at home using Amsler chart
straight lines may appear wavey
will more likely affect both eyes 
Progresses slowly over Sereval years
198
Q

EVES

A 
vary mag
vary brightness / Contrast
auto focus
interact with image
Save image to View later
Portable
Screen reading technology
voice control
no abberations
improved FOV
199
Q

PD: 62

calculate Convergence required in MA and Prism If the spec may of +12.00 D is fitted 27 mm from eyes centre of rotation

A

PD: 60
F: +12.00D
S= 27
100/ 12 = -8.33 cm
MA = 1 / WD = 1 / I - S = 100 / -8.33-2.7=9.066
P = MA X mono CD= 9.066 X 3.1 = 28.18 each eye

200
Q

State 3 disadvantages of Spec magnifiers

A

short WD
Poor illumination
weight /thickness

201
Q

State 3 advantages of Spec magnifiers

A

increased fov
hands free
more acceptable

202
Q

other than a reduced field of view state 2 other Symptoms of retinitis pigmentosa

A

Poor dark adaptation

night blindness

203
Q

another Patient Suffers from retinitis Pigmentosa Explain how a telescope can be used to increase their field at View

A

reverse telescope to minify Images so falls on central retina

204
Q

state the 3 major causes of visual Impairment Certification in england and wales

A

ARMD
Glaucoma
diabetic Retinopathy

205
Q

A Patient attends foa low vision assessment state how you would explain the Purpose of this appointment

A

Help cx use residual vision
enable required tasks to be Performed
aids independence
Improves qualily of life

206
Q

structure of Pelli Robson chart

8 facts

A 
8 Rows
6 letters Per row grouped into 2 triplets
logarithmic design
Used @ 1m 
89% ~ 0.5% Contrast
Same size + spacing
Specific lighting needed
high to low contrast left - right, Top - bottom
207
Q

advantages of contact lenses for Iris coloboma and howthese advantages are achieved

A

cosmetically better - handpainted to match look of other eye
better VA
reduced Photophobia
opaque backing reduces Light Scatter

208
Q

3 Signs of diabetic retinopathy

A

Retinal haemorrhages
micro aneurism
macular Oedema

209
Q

Give 2 reasons Why the results obtained with he simple optometer may not be accurate

A

Difficult to determine astigmatism

Proximal accommodation will under/ over correct

Year 3 (8 decks)

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