Variation of laser-induced retinal injury thresholds with retinal irradiated area: 0.1-s duration, 514-nm exposures

Abstract

The retinal injury threshold dose for laser exposure varies as a function of the irradiated area on the retina. Zuclich reported thresholds for laser-induced retinal injury from $532nm$, nanosecond-duration laser exposures that varied as the square of the diameter of the irradiated area on the retina. We report data for 0.1-s-duration retinal exposures to $514‐nm$, argon laser irradiation. Thresholds for macular injury at $24h$ are 1.05, 1.40, 1.77, 3.58, 8.60, and $18.6mJ$ for retinal exposures at irradiance diameters of 20, 69, 136, 281, 562, and $1081μm$, respectively. These thresholds vary as the diameter of the irradiated retinal area. The relationship between the retinal injury threshold and retinal irradiance diameter is a function of the exposure duration. The 0.1-s-duration data of this experiment and the nanosecond-duration data of Zuclich show that the $ED50$ (50% effective dose) for exposure to a highly collimated beam does not decrease relative to the value obtained for a retinal irradiance diameter of $100μm$. These results can form the basis to improve current laser safety guidelines in the nanosecond-duration regime. These results are relevant for ophthalmic devices incorporating both wavefront correction and retinal exposure to a collimated laser.