Effect of non-mode-locked ultraviolet laser radiation (334 nm) on the retina

The eyes of three rhesus monkeys (Macaca mulatta) were exposed to non-mode-locked ultraviolet (UV) radiation at 334 nm. The beam incident at the corneal plane had a diameter of approximately 2.0 mm and a maximum power of 45-50 mW. Each eye received nine exposures with exposure times ranging from 0.1 to 8.0 s. The animals were euthanized at various times following exposure so that the eyes were examined at approximately 1 h and 1, 2, 5, 7, and 14 d post-exposure. Histologic lesions were primarily seen involving photoreceptors, and were qualitatively similar regardless of duration of exposure; although quantitatively more damage was seen at sites exposed for 4.0 to 8.0 s. The results indicate that retinal sensitivity to UV laser light is a wavelength effect, rather than due to laser mode-locking which was present in an earlier study but absent in this study.