Ocular effects of a 325 NM ultraviolet laser

Corneal exposures were made on 100 eyes of anesthetized rhesus monkeys with a continuous wave HeCd ultraviolet laser at a wavelength of 325 nm. The ED-50 corneal damage probability point was determined to be 0.8 joules of energy. This is higher than the levels for damage reported for noncoherent ultraviolet sources. However, the endpoint used here was a well-defined circumscribed lesion as contrasted to the appearance of granules used for the broad band, wide-beam, noncoherent studies. The granules were not seen with the narrow band, small beam laser irradiation. Exposures made with 6.5 joules of energy produced lens damage, i.e., cataracts. This represents permanent damage as compared to the corneal damage which at threshold levels is completely reversible in 24-48 hours.