Accommodative hysteresis of refractive errors in light and dark fields.

Abstract

We investigated the accommodative hysteresis of the refractive error in the light and also in the dark in 19 healthy young women. We measured refractive error under light and dark conditions using the Nidek Autorefractometer AR 1600 with its target light on or off. Then we measured refractive error in the light and in the dark again after they performed nearwork. Post-task refractive error was measured after reading a magazine for 15 min wearing glasses -3.0 D over their distance correction. Nearwork produced a myopic shift of 0.21 D in the refractive error in the light but no shift in the refractive error in the dark. Refractive error in the dark increased significantly by the near task in eyes with more than 2.0 D of myopia, but it did not increase in eyes with less than 2.0 D of myopia. These apparent differences in the accommodative hysteresis are due to the different pre-task baseline values. If the post-task refractive error is evaluated with the same pre-task baseline value, the accommodative hysteresis does not differ among different refractive errors whether measured in the light or in the dark.