Corneal thermal damage threshold dependence on the exposure duration for near-infrared laser radiation at 1319 nm.

Abstract

The corneal damage effects induced by 1319-nm transitional near-infrared laser have been inves- tigated for years. However, the damage threshold dependence on exposure duration has not been revealed. The in vivo corneal damage thresholds (ED50s) were determined in New Zealand rabbits for 1319-nm laser radiation for exposure durations from 75 ms to 10 s. An additional corneal ED50 was determined at 1338 nm for a 5-ms exposure. The incident corneal irradiance diameter was fixed at 2 mm for all exposure conditions to avoid the influence of spot size on threshold. The ED50s given in terms of the corneal radiant exposure for exposure dura- tions of 5 ms, 75 ms, 0.35 s, 2 s, and 10 s were 39.4, 51.5, 87.2, 156.3, and 311.1 J∕cm 2 , respectively. The 39.4 J∕cm 2 was derived from the ED50 for 1338 nm (27.0 J∕cm 2 ). The ED50s for exposure durations of 75 ms to 10 s were correlated by a power law equation, ED50 ¼ 128.9t 0.36 in J∕cm 2 , where t was the input in the unit of second, with correlation coefficient (R) of 0.997. Enough safe margins existed between the ED50s and the maxi- mum permitted exposures from current laser safety standard. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)