Ocular Effects of Holmium (2.06 μM) and Erbium (1.54 μM) Laser Radiation

Ocular dose-response relationships were experimentally determined for selected exposure conditions at the erbium and holmium laser wavelengths of 1.54 and 2.06 μm. The ocular responses were observed in Rhesus monkey eyes and were confined to the cornea. The EDsos (effective dose for 0.5 probability of producing a biomicroscopically visible corneal lesion) determined for single corneal exposures were as follows: Wavelength Exposure Irradiance ED50 duration diameter 1.54 μm 930 μsec 1.0 mm 9.6 J/cm2 2.06 μm 100 μsec 1.8 mm 2.9 J/cm2 2.06 μm 42 nsec 0.32 mm 5.2 J/cm2 The depth and diameter of the corneal lesions were both dose and wavelength dependent. The wavelength dependence of the dose required to produce a corneal response is indicative of the relative absorption properties of the cornea. These results suggest that current permissible exposure limits be altered to reflect the relative absorption properties of the ocular media.