Flashcards in Amblyopia/Strabismus Deck (27):
20/40 - 20/80
20/100 - 20/400
1. correction of RE
2. occlusion therapy (patching/atropine)
3. vision therapy
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
How much atropine to use?
Moderate: 2 days/week (weekend)
Severe: 2 days/week may be effective
- 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.
Angle of anomaly
Difference between the objective and subjective tropia
- most common type
- angle of anomaly = angle of deviation
- no diplopia
angle of anomaly < angle of deviation
Diplopia present, but not large
Movement of fovea is in the wrong direction, makes diplopia worse because angle of deviation is larger than it initially was
After Image Test
Two lines are shifted horizontally, they have ARC
Heterotropic patients that cannot fuse even with prisms
Two maculas view two different images and they are super imposed
- 30-80 prism diopters
- occurs <6 months
- may be neuorological problem, especially if constant
- typically not amblyogenic because it is alternating
- decreased stereopsis
equal refractive error
Amblyogenic refractive error for hyperopia
>1 D aniso, >5D OU
Amblyogenic refractive error for myopia
>3D aniso, >8D OU
Amblyogenic refractive error for astigmatism
>1.5D aniso, >2.5D OU
- 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
Essentially Hirschberg test, but a prism is used to assess/quantify deviation.
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)
Stereopsis: global testing
Random dot targets which have NO monocular cues.
~20 seconds of arc with contour testing and appreciation for gross random dot tests
- used for fixation disparity testing
- binocular cues for motor fusion
Vectographic slides, Bernell lantern, Wesson fixation card, Sheedy disparometer
Suppression occurs during a saccade to suppress vision eliminating possibility of oscillopsia.
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.