Bv Test interperatation

Question 1

Hirschberg / Krimsky

Answer 1

Hirschberg:
- corneal reflex poition at pupil centre
- normal: apron 0.5mm nasal (~22^ exo angle )

interpretation:
- reflex sifted temporally - eso deviaion
- reflex shifted nasally - exo deviation

Key caution: small deviation unreliable, use krismky if uncertial

Krimsky:
- add prism until reflex is centered - gives deviation outcome

Question 2

Bagolini glasses

Answer 2

Primary sensory test: closest ot natural viewing

Expected normal results: two striaght lines performing a perfect cross, intersecting at fixation light - normla binoc fusion

Key interpertations:
- uncrossed lines = indicates eso pattern, shows that the image falls on the nasal retina suggesting nasal retinal correspondance (eso-type pos)
- crossed lines= indicates eso pattern
- missing part of 1 line - suppression present in the eye, small central gap indicates microtropia suppression scotoma, large dropout indicates full suppression zone.
- lines present but dont intersect - ARC, subjective alignment exists, but not at true fovea.
- Diplopia patterns - homogenous diplopia - eso
- heteronomous diplopia - exo

Bagolini is the single most discriminating test between:
- normal fusion
- suppression
- ARC
-Diplopia

Question 3

Worth 4 dot test

Answer 3

assessses fusion, suppression or diplopia

setup:
- red/green googles
- Px views 4 dot target

expexted normal response:
- sees 4 lights (2 green, 1 red, i mixed) - binoc fusion

interpertation table:
- 4 lights = normal BV
- only 2 red lights = suppression RE
- only 3 green = suppression LE
- 5 lights = Diplopia

Ansons and davis notes:
- suppression that only appears at distance = classic intermittent XOT

Question 4

Synoptophore

Answer 4

Tests:
- assesses objective angle (via motor allignment)
- subjective angle (via fusion alignment)

interpretation:
- objective angle = subjective angle = NRC
- subjective < objective = Harmonius ARC
- Subjecgive > objective = unharmonious ARC
- Diplopia at all settings - no sensory compensation

Formal method of classifiying ARC

Question 5

Stereo tests ( TNO, Random, Timus)

Answer 5

Normal steropsis: intact bifoveal BV

Reduced steropsis:
- Early eso devaition
- microtopia
- constant deviation
- suppression / ARC

flat fusion with no stereo:
- very poor sensory prognosis ( often infantile esotropia)

Question 6

4^ BO test

Answer 6

Hallmark test for microtropia

Method:
- prism BO over suspected microtropic eye
- expect version + vergence eye movements

Normal response:
1. devation eye turns (Vergence)
2. fellow eye counter fixates (vrgence)
- proves both central retae are used

Microtropia response:
- no vergence or version
- means central suppression scotoma present

Note: if the fellow eye reacts, but the devation eye does not - small angle ARC is present

Question 7

Prism Neutralisation

Answer 7

Used durring alternate CT

Distance Vs near findings are key:
- greater eso at near = High AC/A, Accom eso
- Greater exo at distance = intermittent XOT
- similar angles = fully concomitant

if deviation collapses in full cyclo correction = Fully accommodative eso

Question 8

AC/A ratio assessment

Answer 8

Methods:
- gradient
- Heterophoria (preferred in anson and davis)

Findings:
- High AC/A ratio = near Eso > distance Eso, Bifocals likely
- Normal AC/A = angles equal at distance and near
- Low AC/A = Rare, larger in distance than at near

stimulated distance esophoria:
- High AC/A ratio with correstion = induced acommodative drive
- Explains why prism / lenses alters CT findings