Product Code: JLA_20_2_98

Authors:
Karl Schulmeister
Austrian Research Centers, A-2444 Seibersdorf, Austria

David H. Sliney
US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5422

John Mellerio
Department of Ophthalmology, Rayne Institute, St. Thomas’ Hospital, London, SE1 7EH, United Kingdom

David J. Lund
Bruce E. Stuck
US Army Medical Research Detachment, Walter Reed Army Institute of Research, Brooks City-Base, San Antonio, Texas 78235-5108

Joseph A. Zuclich
Northrop Grumman Information Technology, San Antonio, Texas 78288-1330

Laser exposure limits as promulgated by the International Commission on Non-Ionizing Radiation Protection are compared to relevant experimental animal injury data for cornea and lens exposure in the nanosecond to microsecond pulse duration regime in both the ultraviolet (UV) and infrared spectral ranges. In the UV spectral range, thermal and photochemical damage mechanisms compete and thresholds must be carefully distinguished as a function of wavelength and pulse duration. The thermal UV damage data are compared with levels inferred from CO₂ radiation thresholds and it is shown that the reduction factors between experimental data for thermal injury and the corresponding exposure limits appear to be unnecessarily high. The lack of data for nanosecond exposures for wavelengths below 355 nm is identified. Available experimental data for infrared radiation (1.4–4 μm) can be fitted well with an inverse-absorption curve for saline. The exposure limits roughly follow the absorption curve with a varying degree of safety scaling factor. A lack of experimental threshold data is identified for wavelengths around the 3 μm absorption peak for water absorption. The inverse curve for the spectral absorption of water would suggest a rather low threshold for a biological effect at 3 μm.