WEEK 4 AND 5 Flashcards
What is a cause of convergent low amp of acc?
Binoc Amp Accom in Esophoria:
-Esophores use increasing amounts of -FV as they look
nearer
-Increasing -FV generates increasing synkinetic -CA
(-)CA inhibits some of the accom, lowering the amp
accom finding
what happens to the vergence demand in NRA PRA test?
nothing, stays constant
What kind of BA is stimulated in the NRA test? (plus or minus)
what kind of fixation disparity does this trigger? (eso or exO?)
Plus creates myopic blur (lead of accom) which
relaxes +BA, and then stimulates -BA
-Exo FD (crossed disparity) stimulates +FV which
keeps the eyes straight
What is a cause of convergent low NRA results?
High Exophoria & weak FV
most common vergence anomaly:
CI (usually associated w/ acc insuffiency); more women than men
What are 4 shared findings with CI and pseudo CI?
1) Low AC/A
2) Moderate to high Exo, XT at near
3) Poor BO at near
4) Receded NPC
what is a pseudo CI?
doesn’t have enough accommodation to drive vergence
Think accommodative insufficiency with secondary CI
which would benefit from plus lenses, CI or pseudo CI?
pseudo (true CI just gets worse)
are BI prisms a good tx for CIs?
No, bc of prism adaptation
what kind of results would you exoect for MEM with CE?
High Lag with MEM:
Because the patient is unable to reduce fusional or proximal vergence, they reduce accommodative to keep image single (but this reduced accommodation results in a lag and possible blurring of the image)
How do you treat CE?
Plus lenses: Use AC/A ratio to find plus lenses to put patient at ortho or a little exo
(can try VT, but doesn’t always work, usually need bifocals after anyway)
what is the def of fusional vergence dysfunction?
A binocular vision disorder in which the fusional vergence findings are abnormal in both positive (BO) and negative (BI) directions, but AC/A ratio and phorias are normal
Expected norm in 12∆BO/3∆BI flipper test?
12∆BO/3∆BI flipper: 15 cycles/min
what kind of pts typically have fusional vergence dysfunction?
often see in high school, college, and grad students, demonstrating a long standing problem that they adapted to, but have now used up their reserves, resulting in symptoms
How do you do VT for divergence excess?
So for these patients, start with 3D and train backwards to first degree fusion (opposite of normal therapy)
VT will not cure DE but reduces amount of time eye wanders
What’s SHeard’s Criterion?
How much prism should you prescribe?
compensating fusional vergence (CFV) should be twice the phoria
Prism to Prescribe: (2/3)phoria – (1/3)CFV
what are the 3 steps in the flow of vergence training?
- Smooth vergences
- Step vergences
- Stress (ex. BO through plus lenses)
