Abstract
Background: Reaction time is the time between presentation of a stimulus and the appearance of appropriate voluntary response in the subject. The measurement of visual reaction time (VRT) is used to evaluate the processing speed of central nervous system and co-ordination between the visual sense and motor system. Refractive errors were proved to affect the accommodation reaction. Defocusing was known to affect the VRT. However, the influence of the refractive error on VRT was not clearly documented. As blur, defocus, illumination affect lot of psychomotor skills like driving, refractive errors also expected to affect the psychomotor skills.

Aims and Objectives: This study was undertaken with a purpose to measure and compare the VRT in myopic subjects with and without correcting the refractive error with that of VRT of emmetropic subjects.

Materials and Methods: The study was carried out among 112 first year medical students in the age group 18 to 20. 60 emmetropic subjects and 52 myopic subjects were involved in the study. The study was carried out with the help of discriminatory and choice reaction time apparatus. VRT was measured in milliseconds. For myopic subjects, VRT was taken before and after correction of their refractive error. Subjects were presented with two visual stimuli, red and green.

Result: VRT is found to be significantly more in uncorrected myopic subjects as compared to emmetropic subjects for both red and green light stimuli. VRT is found to be significantly less in emmetropic subjects as compared to myopic subjects even after correcting the refracting error.

Conclusion: The myopic people have greater reaction time than emmetropic people even though when their refractive error is corrected. This adds refractive error as a new member in the row of factors that affects the VRT.