Non strabismic Vergence Disorders Flashcards
According to Morgan’s Model which tests conform group B? (List 6)
Positive Fusional Vergence Positive Relative Convergence FCC Monocular cross cylinder Near point retinoscopy NRA
According to Morgan’s Model which tests conform group C? (List )
Phoria
AC/A ratio
According to Morgan, what is the purpose of the data from group C?
Used to decide whether to use prisms, lenses, or VT for correction
According to Morgan, what group is lower than expected with accommodative fatigue?
Group A
According to Morgan, what group is lower than expected in Convergence Dysfunction?
Group B
How do we calculate the AC/A ratio using the heterophoria method?
AC/A = [IPD + (P’-P)]/2
IPD:Inter pupillary distance (cm)
P’: Latent deviation at near (1/3m) in prism diopters
P: latent deviation at distance (6m) in prism diopters
In convergence excess the greater esophoria will be at _____?
Near
In convergence insufficiency the greater exophoria will be at _____?
Near
In divergence excess, the greater exophoria will be at _____?
Distance
In divergence insufficiency, the greater esophoria will be at _____?
Distance
In order to Dx either excess or insufficiency, the difference between distance and near phorias must be _____?
Greater than 5 diopters
What conditions are related to a high AC/A ratio?
Convergence excess
Divergence excess
What conditions are related to a low AC/A ratio?
Convergence insufficiency
Divergence insufficiency
What conditions are related to a normal AC/A ratio?
Vergence dysfunction, basic esophoria, basic exophoria
What is the formula to decide how much prism to prescribe if Percival’s criteria is NOT MET?
P = 1/3 greater phoria - 2/3 the lesser phoria
