Binocular Vision Flashcards
Sudden symptoms of CI
Consider patient having MS or Myasthenia gravis.
CE may accompanied by
Accommodative excess or latent hyperopia
CE must be differentiated from
Pathological causes of accommodative/convergence spasm .
- uveitis, Scleritis
- tertiary syphilis, sympathetic paralysis
- pharmacological
DE
Main symptoms is Diplopia
May lead to intermittent exotropia
PFV ranges are Normal at distance and near.
Patient may have a V pattern Exo deviation
Basic exophoria
Normal AC/A Reduced PFV at D and N Reduced NRA Low lag or lead Inability to fuse BO in VF testing
Fusional vergence dysfunction
Reduced PFV and NFV
-abnormal results with binocular AF testing and normal results with monocular testing
Low lag or lead of accommodation
CI, basic exophoria ,
AE
High lag
CE, Basic esophoria
AI
Accommodative infacility
Reduced NRA and PRA
Difficulty clearing plus and minus lenses.
Critical period to develop Amblyopia is
Critical period of development of the visual cortex from birth to 7-9 yrs of age. First 2-3 yrs of life are most sensitive.
Degree of amblyopia
Moderate = 20/40-20/80 Severe= 20/100-20/400
Plastic period
Time frame when amblyopia can be treated.
Amblyogenic Refractive errors-Anisometripia
Myopia: >3.00D
Hyperopia: > 1.00D
Astigmatism : > 1.50D
Amblyogenic Refractive errors-Isometripia
Myopia: >8.00D
Hyperopia: > 5.00D
Astigmatism : > 2.50D
Anomalous retinal correspondence happens
If the foveal misalignment develops before age of 5
- only happens under binocular condition
- objective angle - subjective angle
In normal correspondence
Subjective angle and objective angle are equal
Harmonious ARC
Sensory adaptation completely corresponds for angle of strabismus
Angle H=Angle A
Paradoxical ARC
Objective and subjective angle are in opposite directions.
A= H +S
Even though the person has ET , he visualizes objects as if he were XT.
Type I= surgical under correction of an ET
Type II= surgical over correction of an XT
Test for eccentric fixation
Visuoscopy
Haidinger’s brush
Maxwell’s spot
Monocular Hirschberg test
Test for ARC
After image test
Bagolini lenses
4 BO test
BO on OD
- If OS makes outward movement and refixates= no suppression of OD and OS
- if OS makes outward movement but doesn’t refuxates= suppression of OS
- if OS doesn’t do both= suppression of OD
After image test
NRC ( ET, XT) = perfect cross image
ARC ET = vertical line to ward the left of the center
ARC XT= vertical line to ward the right of the center
ARC ET and nasal EF = perfect cross
HARC and ET =vertical line to ward the left of the center
HARC and ET and Nasal EF=vertical line to ward the left of the center
Contour stereopsis
Uses laterally displaced targets with Monocular cues.
Better at detecting peripheral stereopsis (> 60seconds of arc)
-wirt circles
-Titmus fly
-animals
Normal result is 20seconds of arc
Midline shift
- Stroke affecting the left side of the brain, pt will have right sided hemiparesis, visual midline will shifted away from effected side, toward left
- Treatment with yoked prism
Aphasia
Difficulty expressing language or difficulty understanding the speech of others.
Apraxia
Motor planning deficit
Binasal occlusion
2BI
Helps to reduce patient symptoms by decreasing the degree of binocular processing .
Sheard ‘s criteria
Most effective for exophorias
S=2/3(D)-1/3(R)
Percival’s criteria
For esophoria
P= 1/3(G)-2/3(L)
