Guidelines for Evaluating Stress on the Fusional System

fusional

which type of vergence is linked to eyestrain & asthenopia?

prism, lenses, VT

what are 3 ways to tx fusional vergence problems

BO

according to Sheard’s you would want to try to use VT to increase the ____ (BI/BO) fusional vergence ranges in exophoria

BI

according to Sheard’s you would want to try to use VT to increase the ____ (BI/BO) fusional vergence ranges in esophoria

exophoria

what does Sheard’s work best for?

1:1 rule

states that the BI recovery should be at least as great as the amount of esophoria; works very well for esophoria

Percival’s criterion

sets the comfort zone as the middle third of width of ZCSBV, from 0 - +3.00D stim to accommodation level; met when the lesser vergence range is at least ½ of the greater vergence range