Ultraviolet-Induced Photochemical Damage in the Ocular Tissues

摘要

Exposure to ultraviolet lasers may result in pathology to either the cornea, lens, or retina of the primate eye. The particular combination of exposure parameters (wavelength, peak power, pulsewidth, pulse repetition rate and total energy delivered) determine the target tissue(s) in each instance. The effect may be acute or chronic, and the implicated damage mechanism categorized as photochemical, photoablative or thermal. The discussion will summarize a number of specific cases where ultraviolet laser radiation affected the cornea, lens and/or retina; will describe the nature of the pathologies; and will indicate what is known about the damage mechanisms in each case. Ranges of exposure parameters where each ocular tissue is the most sensitive will be defined. Data discussed will include the action spectra for far- and near-ultraviolet induced ocular damage; the pulsewidth and total energy dependencies of corneal and lens thresholds; cumulative effects of repeated ultraviolet exposures and repair or recovery rates. Finally, retinal photoreceptor damage resulting from near-UV laser exposures will be described. This apparent photochemical effect was observed following exposure to a 325-nm helium cadmium laser when 0.28 J was delivered to the eye. Keywords: Cornea; Eye; Lasers; Primate; Retina; Threshold; Ultraviolet; Reprints; Laser hazards. (kt)