Monofixation Syndrome Flashcards
To identify an amblyogenic factor, what 2 things are we looking at?
- Ocular alignment
2. Refractive Error
A patient with amblyopia will have the worst VA on what type of chart?
Full chart
What 4 specific tests are performed on amblypic patients?
- VA
- Fixation (CF vs. EF)
- Accom (Amps)
- Saccades (NSUCO)
If the patient has EF, under monocular conditions what portion does the patient use to fixate an object?
non-foveal point
Eccentric fixation is a _______ (monocular/binocular) phenomenon.
Monocular
When a patient has both eyes open, are they using their EF point?
No
This is the reference used to compare all visual directions while monocular; oculocentric
Principle visual direction
This is the value that each PR has that is proportionoal to the distance from the fovea.
Retinomotor Value
Normally, the fovea has what retinomotor value?
0
In central fixation, the ZRMV and PVD are associated with the ____.
- fovea
Zero retinomotor value, Principal Visual Direction
In eccentric fixation, the ZRMV and PVD are associated with the ____.
- EF location/spot
- called eccentric localization
In eccentric viewing, the ZRMV is associated with ____ and the PVD is associated with ____.
ZRMV = EF location
PVD = fovea
- no eccentric localization is present
Eccentric fixation is most often associated with what type of amblyopia? what %?
- strabismic amblyopia (60-80%)
How is eccentric fixation described?
- Which Eye
- Direction (which part of retina)
- Magnitude
- Stability
Esotropes tend to have what direction EF?
Nasal EF
Exotropes tend to have what direction EF?
Temporal EF
EF is usually how many prism diopters off?
3-4pd or less
What’s easier to treat: unsteady or steady EF?
Unsteady EF
- more peripheral = less steady
How do we objectively measure EF?
Visuoscopy
- most common method
- monocular test
How do we subjectively measure EF?
- Haidinger’s brush
2. BGAIT
The magnitude of EF in Haidinger’s Brush is determined by what conversion factor at 40cm?
4mm = 1pd
For BGAIT, which eye do you flash first?
non-amblyopic (good) eye
The patient must have what type of correspondence for the BGAIT to work?
normal correspondence
The magnitude of EF in BGAIT is determined by what conversin factor at 1m?
1cm = 1pd
What are the 2 mechanisms by which EF contribute to decreased VA?
- Sensory inhibition
2. Motor (EF)
What equation is used to determine the decrease in VA from EF ONLY?
20/(1+ef)(20)
