The retinal damage and dazzling effects of three-primary color lasers and their synthetic white laser on rabbit eyes.

Abstract

Purpose: With the increasing use of diode lasers emitting in the visible light spectrum, concerns about their potential to dazzle and cause eye damage have grown. This study aims to determine the maximum safe exposure levels and evaluate the retinal damage and dazzling effects caused by red, green, blue, and synthetic white lasers.

Materials and methods: A chinchilla grey rabbit model was used for experimentation. Lasers with wavelengths of 635 nm (red), 520 nm (green), and 456 nm (blue), along with their combined output as synthetic white light, were directed at the rabbits' eyes for 0.2 s. Retinal damage was assessed using a fundus camera at 1 h and 24 h post-irradiation. Histological analysis was conducted to evaluate tissue changes. The dazzling effect was measured by recording the b-wave recovery time in the electroretinogram 0.1 s after laser exposure.

Results: The maximum safe power density levels for red, green, blue, and synthetic white lasers were found to be 140, 60, 35, and 55 mJ/cm², respectively. Exposures exceeding these thresholds resulted in visible retinal damage, including white-coagulated spots, hemorrhages, and corresponding histopathological changes. At an exposure level of 12.0 mJ/cm², the b-wave recovery times for green, blue, and synthetic white light were 9.0, 8.0, and 7.8 s, respectively, while no dazzling effect was observed with the red laser.

Conclusions: The synthetic white light laser exhibited slightly inferior safety compared to the green laser but was significantly safer than the blue laser, with fewer dazzling effects. These findings provide valuable insights for the safe use of visible light lasers.