Amblyopic eyes have longer reaction times

The RT (reaction time) to a 0.25 degree spot of light was measured monocularly on 25 normal subjects and 36 strabismic patients. The overall mean RT and the delta RT (difference in RT between the right and left eyes) for the 19 strabismic patients without amblyopia did not differ significantly from that of the normal subjects. The overall mean RT of the dominant eyes of the 17 amblyopic patients did not differ significantly from that of either the faster of slower eyes of the normal subjects. The overall mean RT of the amblyopic eyes was significantly longer than that of the normal subjects. The delta RT was significantly larger in the amblyopic patients. A regression analysis of the visual acuity of the amblyopic eye and the delta RT showed that the data was best fit by a linear equation. The coefficient of correlation was +0.82. Additional experiments showed that the longer Rt of the amblyopic eyes was not caused by eccentric fixation or by the reduced visual acuity.