Amblyopia/Strabismus

Question 1

Moderate Amblyopia

Answer 1

20/40 - 20/80

Question 2

Severe Amblyopia

Answer 2

20/100 - 20/400

Question 3

Amblyopia Treatment

Answer 3

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

Question 4

How many hours a day to patch:

a) moderate amblyopia
b) severe amblyopia

Answer 4

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

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

Question 5

How much atropine to use?

Answer 5

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

Question 6

Atropine SE

Answer 6

• 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.

Question 7

Angle of anomaly

Answer 7

Difference between the objective and subjective tropia

Question 8

Harmonious ARC

Answer 8

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

Question 9

Unharmonious ARC

Answer 9

angle of anomaly < angle of deviation

Diplopia present, but not large

Question 10

Paradoxical ARC

Answer 10

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

Question 11

After Image Test

Answer 11

Two lines are shifted horizontally, they have ARC

Question 12

Horror fusions

Answer 12

Heterotropic patients that cannot fuse even with prisms

Question 13

Visual confusion

Answer 13

Two maculas view two different images and they are super imposed

Question 14

Infantile/congenital Exotropia

Answer 14

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

Question 15

Isometropia

Answer 15

equal refractive error

Question 16

Amblyogenic refractive error for hyperopia

Answer 16

> 1 D aniso, >5D OU

Question 17

Amblyogenic refractive error for myopia

Answer 17

> 3D aniso, >8D OU

Question 18

Amblyogenic refractive error for astigmatism

Answer 18

> 1.5D aniso, >2.5D OU

Question 19

Hirschberg Test

Answer 19

• 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

Question 20

Krimsky Test

Answer 20

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

Question 21

Stereopsis: contour testing

Answer 21

Laterally displaced targets which allows for monocular cues.

• Titmus fly, animals and Wirt circles
• better for detection for peripheral stereopsis (>60s of arc)

Question 22

Stereopsis: global testing

Answer 22

Random dot targets which have NO monocular cues.

Question 23

Normal stereopsis

Answer 23

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

Question 24

Mallet box

Answer 24

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

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

Question 25

Saccadic suppression

Answer 25

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

Question 26

Form deprivation amblyopia

Answer 26

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

Examples: congenital cataracts, ptosis, corneal opacity.

Question 27

Refractive amblyopia

Answer 27

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