[Laser lesions of the anterior segment of the rabbit eye. Studies of cornea, iris, lens and sclera using an argon, ruby and YAG-laser].

The anterior segment of the eye of 100 rabbits was exposed to radiation from Argon, Ruby and YAG lasers. The healing process of liminal and supraliminal lesions was evaluated histologically. The iris is the most sensitive tissue for all three lasers (threshold radiant exposure, Argon: 0.004 kJ/cm2, Ruby: 0.01 kJ/cm2, YAG: 0.05 kJ/cm2). Higher energies necessary for lesions in the transparent media were available only with the Argon and YAG lasers. The Argon laser failed to produce lesions in the lens, and threshold radiant exposure for the central cornea was 8 kJ/cm2. The thresholds for YAG lasers lesions in the central cornea and lens were of the same magnitude. The marked absorption of energy by the iris may lead to an accumulation of heat, resulting in lesions of adjacent tissues or a reduction of threshold for those lesions: The threshold in the peripheral cornea was ten times lower than in the center with the Argon laser, four times lower for the YAG laser. The thresholds for Argon and YAG laser lesions in the peripheral sclera lay between the thresholds for the iris and for the peripheral cornea. A safety standard for the anterior segment of the eye should be based on the lowest threshold (Argon laser lesion of the iris). The application of a factor 100 results in a maximal permissible exposure of 40 mJ/cm2. The influence of the beam diameter could not be evaluated.