VISFUN: SEMINARS (2) - Ageing Vision, ARC

Question 1

What are the major eye conditions over 40yo [Ageing Vision #1]

Answer 1

Presbyopia
Glaucoma
AMD
Cataract
DR

Question 2

What are the major eye conditions over 60yo [Ageing Vision #1]

Answer 2

Glaucoma
Cataract
AMD
DR

Question 3

What should an Optometrist consider when dealing with an older patient? [Ageing Vision #1]

Answer 3

• ability to live independently
• quality of life + operation necessity (shorter benefit)
• disability
• driving

Question 4

How does ageing affect eyelids? [Ageing Vision #2]

Answer 4

• gradual tissue atrophy (redundant skin folds/wrinkles)
• loss of structural support (tarsus, canthal tendons, orbicularis muscle)
• — orbital fat prolapse, eyelid malposition, blepharoptosis, tearing
• ectropia/entropia

Question 5

How does ageing affect horizontal eye fissure? [Ageing Vision #2]

Answer 5

Decreases by about 10%

Question 6

How does ageing affect cornea? [Ageing Vision #2]

Answer 6

• increased epithelial permeability
• changed integrin subunit distribution
• reduced phagocytic ability of granulocytes (in response to infection)

Question 7

How does ageing affect size/density of corneal layers? [Ageing Vision #2]

Answer 7

• thickened epithelial basement membrane
• decrease nerve density
• decreased stromal cell density
• Thickened Descement’s membrane + appearance of hassall-henie bodies
• Decreased number of corneal endothelial cells

Question 8

How does ageing affect TM and Iris? [Ageing Vision #2]

Answer 8

TM: increased pigmentation, increased aq. outflow resistance
Iris: decreased pigmentation, less refractive + more difficult to dilate, decreased size

Question 9

How does ageing affect crystalline lens? [Ageing Vision #2]

Answer 9

• decreased lens optical density
• nuclear sclerosis (lens hardening)
• more yellow pigment
• decreased elasticity of capsule
• decreased fibre compactness

Question 10

How does ageing affect the vitreous? [Ageing Vision #2]

Answer 10

• harmless floaters
• condensation of vitreous gel
• increased mobility of fibrillary structures
• lacunae (optically empty spaces)
• vitreous body shrinkage

Question 11

How does ageing affect the retina? [Ageing Vision #2]

Answer 11

• thickened ILM (internal limiting membrane)
• neuronal cell loss + degradation
• gliosis (in peripheral retina)
• disorganisation of ora serrata and RPE
• reduced nuclei in ONL
• corpora amylacea
• loss of rods

Question 12

How does ageing affect retinal vessels? [Ageing Vision #2]

Answer 12

• loss of cellularity in peripheral capillaries
• attachment of ILM to peripheral vascular arcades
• reduced number of capillaries around fovea
• arteriosclerotic changes

Question 13

How does ageing affect dark adaptation? [Ageing Vision #3]

Answer 13

Decreased light sensitivity due to impaired visual cycle (poor regeneration of rhodopsin)

Question 14

How does ageing affect contrast sensitivity? [Ageing Vision #3]

Answer 14

Decreased at intermediate and high spatial frequencies due to retinal + neural factors

Question 15

How does ageing affect visual acuity? [Ageing Vision #3]

Answer 15

Worse VA (compared to young) in low luminance and contrast conditions

Question 16

How does ageing affect Critical Flicker Frequency? [Ageing Vision #3]

Answer 16

Decreases. Not due to pupil size but potentially due to stimulus persistence theory

Question 17

How does ageing affect visual fields? [Ageing Vision #3]

Answer 17

Depends on ocular disease progression

Question 18

What is Anomalous Retinal Correspondance? [Arc #1]

Answer 18

A.K.A ‘Abnormal Retinal Correspondance’
- is a binocular adaptation to compensate for eye deviation where the fovea of one eye has a common visual direction with an extrofoveal area in the other eye.

Question 19

Explain how ARC works [Arc #1]

Answer 19

When you have a turned eye, an image falling on the fovea of that turned eye will be projected at a non-corresponding point to the other eye. In ARC, the image lands on a “psuedofovea” of the turned eye: a compensation mechanism to prevent diplopia

Question 20

What is Normal Retinal Correspondance? (NRC) [Arc #1]

Answer 20

Is when an image falls on both foveas, regardless of whether one eye is turned or not

Question 21

Describe the vision of a strabismic (turned eye) patient who has NRC? [Arc #1]

Answer 21

Diplopia

Question 22

Describe the vision of a strabismic patient who has ARC? [Arc #1]

Answer 22

Not diplopia

Question 23

What is the angle of anomaly? [Arc #1]

Answer 23

describes the degree of visual deviation between eyes for a strabismic patient (i.e. the degree of shift in visual direction)

Question 24

How do you mathematically calculate the angle of anomaly in a strabismic patient? [Arc #1]

Answer 24

Objective Angle - Subjective Angle

• objective angle: difference between location of the ‘true fovea’ and image location
• subjective angle: difference between location of the ‘pseudofovea’ and image location

Question 25

What does the objective angle represent (in strab with ARC)? [Arc #1]

Answer 25

difference between location of ‘true fovea’ and image location

Question 26

What does the subjective angle represent (in strab with ARC)? [Arc #1]

Answer 26

difference between location of ‘psuedofovea’ and image location

Question 27

Name the 3 different types of ARC [Arc #2]

Answer 27

• Harmonius: angle of anomaly = angle of deviation
• Unharmonius: angle of anomaly less than angle of deviation
• Paradoxical: angle of anomaly more than angle of deviation

Question 28

What visual symptom arises from unharmonius and paradoxical ARC [Arc #2]

Answer 28

Diplopia, because the psuedo-fovea does not fully compensate for the angle of deviation

Question 29

Can unharmonius ARC be made harmonius? [Arc #2]

Answer 29

Yes it can

Question 30

What type of diplopia results from the following in unharmonius ARC: esotropia and exotropia? [Arc #2]

Answer 30

Esotropia: uncrossed diplopia
Exotropia: crossed diplopia

Question 31

What type of diplopia results from the following in paradoxical ARC: esotropia and exotropia? [Arc #2]

Answer 31

Esotropia: crossed diplopia
Exotropia: uncrossed diplopia

(because it’s paradoxical)

Question 32

What 2 techniques can you use to classify ARC? [Arc #2]

Answer 32

• Synoptophore

- Worth 4 light

Question 33

Explain the worth’s 4 light test setup [Arc #2]

Answer 33

4 circular lights (2 green, 1 red, 1 white). Right eye with red filter sees red dot and white dot; left eye with green filter sees green dots and white dots

Question 34

What would a person NRC see in the worth 4 light test? [Arc #2]

Answer 34

Sees all dots correctly in each eye and only sees 4 dots (simultaneous perception and sensory fusion). (right eye sees red and left eye sees green)

Question 35

What would a person with harmonius ARC see in the worth 4 light test? [Arc #2]

Answer 35

Sees 4 lights

Question 36

How many lights on the worth 4 light test would be seen in a patient with double vision? [Arc #2]

Answer 36

Will see 5 lights

Question 37

In the worth 4 light test, how would the dots appear in diplopia with esotropia vs exotropia? [Arc #3]

Answer 37

esotropia (uncrossed): red dots on right side, green on left

exotropia (crossed): red dots on left side, green on right

Question 38

How does the horopter for exotropic subjects with harmonius ARC compare to normal? [Arc #3]

Answer 38

• similar but steeper curve (slightly skewed)
• abnormal points peripherally
• points don’t really align very well

Question 39

How does the horopter for esotropic subjects with harmonius ARC compare to normal? [Arc #3]

Answer 39

• horopter exhibits a local convexity or ‘notch’ which is closer to the visual axis of the better eye

Question 40

How would you describe the spatial vision of amblyopic patients [Arc #3]

Answer 40

Experience distortion patterns

Question 41

What treatments are available for ARC? [Arc #4]

Answer 41

• Occlusion,
• Orthoptic Exercise
• Surgery
• Prisms