22 May 1995 Ocular effects of penetrating IR laser wavelengths
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Abstract
This study is concerned with ocular effects of laser radiation in the wavelength range from approximately equals 1.1 micrometers to 2.0 micrometers which includes the so-called 'eye-safe' range where retinal and corneal damage thresholds are significantly higher than the corresponding thresholds for more common visible and far-IR lasers. Across this wavelength range, ocular safe exposure limits vary rapidly with wavelength and are up to approximately equals 6 orders of magnitude greater than exposure limits for visible wavelengths. However, recent developments in laser technology have yielded a variety of powerful near-IR laser sources. Such lasers are not 'eye safe' but, rather, may emit peak powers orders of magnitude above tissue-damaging levels. This report focuses on the unique aspects of laser-tissue interactions for 'eye-safe' wavelengths. In contrast to past experience where the laser energy is absorbed primarily in a thin layer (either at the corneal or skin surface for longer IR wavelengths or at the retinal pigment epithelium for visible wavelengths), 'eye- safe' wavelengths are attenuated gradually through a volume of tissue and may affect any one or several sites within the cornea, lens, and retina. The reaction of the irradiated organism to the volumetric heating associated with such penetrating laser wavelengths does not conform with expectations of an immediate or relatively early observable lesion. Rather, the observable consequences of the laser exposure may take days to become apparent and may involve degeneration across a wider expanse of tissue than that directly irradiated by the laser. For these reason, IR laser exposures bear close scrutiny to redefine both the usual tissue damage criteria and then the appropriate safe exposure limits.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joseph A. Zuclich, Donald A. Gagliano, F. Cheney, Bruce E. Stuck, Harry Zwick, Peter R. Edsall, David J. Lund, "Ocular effects of penetrating IR laser wavelengths", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); doi: 10.1117/12.209874; https://doi.org/10.1117/12.209874
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