Amblyopia/Strabismus Flashcards Preview

Binocular/Colour/Perceptual Vision > Amblyopia/Strabismus > Flashcards

Flashcards in Amblyopia/Strabismus Deck (27):
1

Moderate Amblyopia

20/40 - 20/80

2

Severe Amblyopia

20/100 - 20/400

3

Amblyopia Treatment

1. correction of RE
2. occlusion therapy (patching/atropine)
3. vision therapy

4

How many hours a day to patch:
a) moderate amblyopia
b) severe amblyopia

a) 2 hours/day + 1 hour of near activitiy
b) 6 hours/day + 1 hour of near activitiy

5

How much atropine to use?

Moderate: 2 days/week (weekend)
Severe: 2 days/week may be effective

6

Atropine SE

- increased blood pressure
- mental confusion
- increased pulse
- dryness of mouth and throat
- loss of neuromuscular coordination

^ very rare

Hot as a hare, mad as a hatter, dry as a bone.

7

Angle of anomaly

Difference between the objective and subjective tropia

8

Harmonious ARC

- most common type
- angle of anomaly = angle of deviation
- no diplopia

9

Unharmonious ARC

angle of anomaly < angle of deviation

Diplopia present, but not large

10

Paradoxical ARC

Movement of fovea is in the wrong direction, makes diplopia worse because angle of deviation is larger than it initially was

11

After Image Test

Two lines are shifted horizontally, they have ARC

12

Horror fusions

Heterotropic patients that cannot fuse even with prisms

13

Visual confusion

Two maculas view two different images and they are super imposed

14

Infantile/congenital Exotropia

- 30-80 prism diopters
- occurs <6 months
- may be neuorological problem, especially if constant
- typically not amblyogenic because it is alternating
- decreased stereopsis

15

Isometropia

equal refractive error

16

Amblyogenic refractive error for hyperopia

>1 D aniso, >5D OU

17

Amblyogenic refractive error for myopia

>3D aniso, >8D OU

18

Amblyogenic refractive error for astigmatism

>1.5D aniso, >2.5D OU

19

Hirschberg Test

- tested at 50cm
- difference in angle is termed lambda

Normal angle lambda: slight nasal displacement by ~0.5mm

Nasal displacement from normal represents exotropia.
Temporal - esotropia
Superior - hypotropia

1mm = 22 prism diopter

20

Krimsky Test

Essentially Hirschberg test, but a prism is used to assess/quantify deviation.

21

Stereopsis: contour testing

Laterally displaced targets which allows for monocular cues.

- Titmus fly, animals and Wirt circles

* better for detection for peripheral stereopsis (>60s of arc)

22

Stereopsis: global testing

Random dot targets which have NO monocular cues.

23

Normal stereopsis

~20 seconds of arc with contour testing and appreciation for gross random dot tests

24

Mallet box

- used for fixation disparity testing
- binocular cues for motor fusion

Other examples:
Vectographic slides, Bernell lantern, Wesson fixation card, Sheedy disparometer

25

Saccadic suppression

Suppression occurs during a saccade to suppress vision eliminating possibility of oscillopsia.

26

Form deprivation amblyopia

Obstruction of a clear image to the retina before the age of 6-8 years of age.

Examples: congenital cataracts, ptosis, corneal opacity.

27

Refractive amblyopia

Large amount of anisometropia between the two eyes, anisometropic amblyopia, or large amount of refractive error in both eyes (isometropic amblyopia)