The Effect of Blue-blocking Lenses on Photostress Recovery Times.

Abstract

The selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses (BBLs) is known to influence the appearance and contrast detection of objects, particularly at low light levels. This influence may impair the human retinal receptor response time to dynamic light changes during photostress events. This study aimed to assess whether BBLs selectively affect photostress recovery times (PSRTs) for chromatic and achromatic stimuli of different Weber contrasts that were viewed on a dark black background. Photostress recovery times were measured in 12 younger participants (18 to 39 years old) with no history of ocular disease or abnormal vision. Photostress recovery times were evaluated for four brands of BBLs, which were compared with a control lens. In these experiments, after exposure to an intense light source for 5 seconds, the time taken to recover vision and correctly identify a computer-generated letter stimulus viewed under low and high luminance levels was determined, which means perception is likely to be governed by mesopic and photopic conditions. Across conditions, the letter stimulus was achromatic and chromatic and could differ in luminance contrast. Under photopic stimulus conditions, although reducing luminance contrast increased PSRTs, BBLs had no significant effect on PSRTs relative to control lens. However, under mesopic stimulus conditions, BBLs significantly affect PSRTs for both achromatic (F2.006,8.02 = 61.95, P < .0001) and chromatic stimuli (F3,16 =139.01, P < .0001), particularly for blue targets, which had considerably longer PSRTs (38.40 seconds). The brand of BBL was also shown to selectively affect PSRTs, with those with transmittance profiles that block the most blue light having longer PSRTs. The present study suggests that, although the color and contrast of the target stimuli affected recovery times, the difference in recovery times between different types of BBLs was noticed only under low-light-level stimulus conditions.