High-power lasers in the 1.3-1.4 μm wavelength range:: ocular effects and safety standard implications

This manuscript details recent studies of ocular effects of pulsed and cw laser radiation at wavelengths of 1.315 and 1.318 mum, and compares corneal, lens and retinal damage thresholds. The results indicate that for the exposure conditions studied, relatively minor changes in pulsewidth and/or wavelength can substantially alter threshold levels and change the tissue site(s) exhibiting the lowest damage threshold. The discussion suggests that these data may be applied to re-assess laser safety standards in the near-IR to far-IR transition-region. Also discussed are unique aspects of the laser-tissue interaction for these penetrating wavelengths where the incident laser radiation is relatively evenly absorbed throughout the ocular medium and the retina. In such cases of "volumetric" absorption observable manifestations of laser insult may be delayed (hours to days) and may ultimately involve inflammatory responses or other disruption of tissue not directly irradiated by the laser.