Retinal Defocus and Eye Dominance Effect on Eye-Hand Reaction Time

Purpose: To study the effect of retinal defocus and sighting eye dominance on simple eye-hand reaction time in young visually-normal adults. Methods: Sixteen visually-normal individuals participated in a simple eye-hand reaction time test with different amounts of spherical and astigmatic retinal defocus introduced binocularly in the spectacle plane (plano to +10.00D sphere and +0.50 to +2.00D cyl). Reaction time was assessed under binocular-viewing conditions using the RT-2S Simple Reaction Time Tester. The test target color and size simulated a conventional traffic signal. In addition, sighting eye dominance testing was performed monocularly with different defocus amounts introduced before each eye on a subset of eight subjects. Results: There was no significant effect (p>0.05) of either spherical or astigmatic retinal defocus, or eye dominance, on simple eye-hand reaction time. However, gender differences revealed a consistent and significant effect of retinal defocus (p<0.001), with males being faster by approximately 30 msec across the range of retinal defocus conditions. Conclusions: Simple eye-hand reaction time was robust to a wide range of amounts and types of retinal defocus, thus suggesting central neural insensitivity to blur for this simple performance task and target. The gender difference may be related to visuomotor experience.