Saccadic reaction times in alternating cover.

Objective: The aim of this study was to compare saccadic reaction times (SRTs) during the alternating cover with SRTs during monocular viewing.

Methods: Seven subjects with intermittent exotropia, eight subjects with esophoria and ten control subjects were participated. The normal-task was to fixate the central fixation point until the peripheral target appeared randomly either 5 degrees to the right or left. In the alternating cover task (AC-task), the cover was switched from the fixating eye to the other eye, central fixation target was simultaneously extinguished and peripheral target was lit. An infrared limbal-tracking system and electro-oculogram were used for measurements of eye movements. The study followed the tenets of the Declaration of Helsinki. We certify that there is no conflict of interest.

Results: In AC-task, the average SRTs of control subjects, subjects with exophoria and subjects with intermittent exotropia were 224.2 ± 46.5 ms, 198.2 ± 45.3 ms and 227.3 ± 69.9 ms, respectively. On the other hand, the average SRTs of control subjects, subjects with exophoria and subjects with intermittent exotropia in normal-task were 200.7 ± 37.8 ms, 178.2 ± 34.6 ms and 185.4 ± 54.1 ms, respectively.

Conclusions: The SRTs of most control subjects, subjects with exophoria and subjects with intermittent exotropia in AC-task were prolonged compared to normal-task.