DISSOCIATION BETWEEN VISUAL-ACUITY AND CRITICAL FLICKER FREQUENCY IN AMBLYOPIA

Purpose To determine the occurrence and possible mechanism of enhanced foveal critical flicker frequency (CFF) in untreated amblyopic indivi duals. Methods Thirty untreated amblyopic subjects were enrolled. CFF was measured in each eye and performance was compared between their am blyopic and fellow non-amblyopic eyes. CFF was also compared between a mblyopic eyes demonstrating foveal and eccentric fixation. Results As a group, there was no significant difference in CFF between amblyopic eyes and fellow eyes. However, CFF was significantly faster in affecte d eyes of amblyopes who fixated eccentrically than in affected eyes of amblyopes who demonstrated foveal fixation. Conclusions Dissociation between visual acuity impairment and CFF occurs in amblyopes who use e ccentric fixation. Stimulation of a greater proportion of magnocellula r, relative to parvocellular, retinal ganglion cells might account for the paradoxically enhanced CFF performance of this subset of amblyopi c eyes.