3. Consequence of Squint & Amblyopia

Question 1

Why does suppression only occur when both eyes are open?

Answer 1

Because the aim is to take away diplopic image. And eliminate confusion.

Question 2

Can adults learn how to suppress?

Answer 2

No

Question 3

Uncrossed vs Crossed diplopia?

Answer 3

Uncrossed: Image falls on nasal retina (Same side as squinting eye). In esotropic eyes.
Crossed: Image of fixation object falls on temporal retina, on the opposite side of squinting eye.

Question 4

What is suppression?

Answer 4

Mental inhibition of one eye in favor of the other to avoid diplopia and confusion.

Question 5

Suppression of fovea VS Suppression of peripheral retina?
This 2 points are measured together as?

Answer 5

Suppression of fovea: Avoid diplopia.
Suppression of peripheral retina: Avoid confusion
This 2 points extend and become measured as suppression scotoma.

Question 6

How does confusion arise in tropic eyes?

Answer 6

Fovea of squinting eye may be simulated by another object in the visual field, this is not the same as the image simulated on the fovea of the straight eye, images are hence not fused and superimposed leading to confusion.

Question 7

Is it possible for children with esotropia to have it eliminated eventually?

Answer 7

Yes, eyes naturally diverge with time. Hence, possible for children to grow out of an esotropia, and they come out of the suppression scotoma.

Question 8

Why do patients with childhood squints + suppression complain of diplopia?

Answer 8

Because adults do not learn how to suppress.

Question 9

Density of suppression is measured using?

Answer 9

Sbisa bar

Question 10

Who develops suppression?

Answer 10

Children within plastic period.

Question 11

Suppression leads to?

Answer 11

Amblyopia

Question 12

What is amblyopia?

Answer 12

The visual pathway doesn’t develop correctly, hence clear image not sent to the brain, lack of clear image leads to suppression if a diploic image, blurred vision and reduced VA.

Question 13

7 Classifications of Amblyopia?

Answer 13

1. Strabismic
2. Stimulus deprivation
3. Anisometric
4. Ametropic
5. Meridional
6. Idiopathic
7. Organic

Question 14

What is congenital 4th nerve u/a?

Answer 14

Congenital SO weakness that results in a vertical deviation

Question 15

What is distance exotropia?

Answer 15

Px exotropic at distance and esophoric at near.

Question 16

Who has stimulus deprivation amblyopia?

Answer 16

In children with ptosis, child over patched, child with hemangioma.

Question 17

What is anisometric amblyopia?

Answer 17

Occurs due to significant difference is refractive errors between both eyes. Difference in acuity and image size between both eyes, leading to suppression in eye with poor VA which later causes amblyopia.

Question 18

What is meridional amblyopia?

Answer 18

Result of uncorrected refractive error.

Question 19

What is ametropic amblyopia?

Answer 19

Bilateral amblyopia due to uncorrected bilateral refractive error.

Question 20

What is idiopathic amblyopia?

Answer 20

Non known cause of amblyopia, but improves with occlusion could be due to corneal scar, ulcer.

Question 21

Aim of amblyopia treatment?

Answer 21

To restore visual acuity of amblyopic eye.

Question 22

How is amblyopia treated by occlusion?

Answer 22

Patch over better eye.
Total occlusion = Excludes light & form.
Partial occlusion = Transucent occlusion, appreciate form, dimmish acuity.

Question 23

When is total vs partial occlusion done?

Answer 23

Partial occlusion done when bilateral amblyopia, with alternating occlusion.

Question 24

3 types of penalization

Answer 24

Distance, near & total

Question 25

1. Use of cycloplegic drugs as amblyopia treatment aims to?
2. What drug is used?
3. Ideally used in?

Answer 25

1. Principle to blur the vision of the better eye by preventing accommodation and decreasing depth of focus.
2. 1% atropine
3. Children with poor compliance

Question 26

4 contraindications of cyclopic drugs for treating amblyopia?

Answer 26

1. Previous poor attendance.
2. History of cardiac problems.
3. Dense amblyopia
4. Minimal amblyopia

Question 27

6 indications of type and duration of therapy?

Answer 27

1. Vision- Poor vision= more occlusion
2. Age- Older children are less plastic hence more occlusion
3. Duration of squint- Longer the duration, poorer the VA, more occlusion needed.
4. Intermittent/ latent squint- Partial squint
5. Latent nystagmus- conventional occlusion will increase nystagmus hence, atropine occlusion.
6. Contraindications- consider social circumstances, general health, allergies

Question 28

Timing of visit depends on what 4 factors?

Answer 28

1. Type of occlusion therapy
2. Age of px
3. Risk of intractable diplopia
4. Risk of decompression

Question 29

How does VA testing with crowding effect px’s with amblyopia?

Answer 29

Amblyopic eyes demonstrate poor acuity when tested with crowding, consider testing with individual letters to get better and accurate results.

Question 30

4 important advise for px’s when occluding?

Answer 30

1. Which eye to occlude
2. Duration of occlusion
3. Possible side effects
4. Safety precautions

Question 31

When is occlusion stopped?

Answer 31

1. Equal VA obtained
2. When alternation occurs
3. No further improvement
4. Risk of diplopia or decompensation

Question 32

How to ensure stability when eye is occluded?

Answer 32

Checked childs VA on 2 occlusions to identify stability in VA.

Question 33

Amblyopia only affects distance VA, true or false?

Answer 33

False, it affects both distance & near VA.