Chapter 1 Flashcards
Knapp’s Law
Axial ametropia vs Refractive ametropia (glasses or contacts?)
Axial: glasses
Refractive: contacts
Javal’s rule to compensate for lenticular astigmatism
Add -.50 ATR (to compensate for lenticular astig in all eyes)
To convert to plus cylinder put on a optical cross and write the most minus first
True
When you scope with light vertical you are scoping the 180
True
When you scope with the light horizontal you are scoping the 90
True
Accommodative demand in diopters is equal to the reciprocal of the working distance
True
Barrel distortion occurs with high myopic or hyperopic?
Myopic
AC/A ration in CE and CI
CE = high AC/A CI = low AC/A
Basic exophoria
about the same phoria at far and near
DE (divergence excess)
Too exo at distance
DI
Too eso at distance
CE
Too eso at near
CI
Too exo at near
AC/A equation
= PD (cm) + working distance (M)(near phoria-distance phoria) eso is (-) and exo is (+)
Formula for accommodative amplitude for age
= 18.5 - (.3)age
Adding plus makes the eyes more eso or exo?
Exo
Pseudo CI
Just need plus lenses. Its an accomm issue not a vergence issue
Sheard’s criterion for prism
= 2/3 (phoria) - 1/3(vergence)
Flipper tests what?
Accommodative facility
normal (for age 13-3-) is 8 cycles per minute binocular
and 12 cycles per minute monocular
PRA test add minus and it stimulates accommodation and tests ____________
divergence (negative fusional vergence)
NRA test add plus and it relaxes accommodation and tests _____________
convergence (positive fusional vergence)
Anytime you have a sudden onset vertical diplopia think of what muscle problem
Superior oblique palsy
Percival’s criterior
Prism = 1/3(greater vergence) - 2/3(lesser vergence)
Negative fusional vergence is
divergence
Positive fusional vergence is
convergence
Sherrington’s Law
For every EOM that is innervated, there is an EOM of the same eye that is inhibited
Herring’s Law
Equal innervation
COWS
In healthy person nystagmus is induced by cold opposite, warm same
Worth 4 Dot test
Sees 4 dots = normal
5 dots = strabismus
2 dots = left eye suppression
3 dots = right eye suppression
On Von Grarfe vertical phoria testing how would you write it if the result is 2 BU over left eye?
2 prism diopters RHP (the patient has Left hypophoria but you always record the hyperphoria so it’s a right hyperphoria)
Negative relative accommodation is adding what lenses to eye for patient to clear?
Plus
Positive relative accommodation is adding what lenses to the eye for patient to clear?
Minus
DEM test
Developmental eye movement test. Tests saccades.
When given NRA and PRA and asked to find the add…
…add them and divide by 2
