Ocular hazards of Q-switched blue wavelength lasers

Abstract

The threshold for laser-induced retinal damage in the rhesus eye was determined for 14 wavelengths from 410 nm to 580 nm. The laser source was a tunable Optical Parametric Oscillator (OPO) pumped by the 3rd harmonic of a Nd:YAG laser. The laser pulse duration was 3.5 ns. The wavelength dependence of the injuiy threshold was consistent with the prediction of a model based on the transmission of the preretinal ocular media, absorption in the retinal pigment epithelium, and variation of h-radiance diameter resulting from chromatic aberration of the eye optics. The threshold for 24hour observation was only slightly lower than the threshold for 1-hour observation. The laser-induced retinal hemorrhage threshold was less than a factor of two greater than the minimum visible lesion (MVL) threshold for wavelengths from 442 nm to 410 nm. This results from the presence ofa dense capillary network in the inner retina and a large hemoglobin absorption peak.