The Krypton ion Laser produces light at three wavelengths which are of interest for their potential use of Photocoagulation therapy. The green line will allow more precise control in occlusion of arterial vessels than is possible with the Argon green or blue lines currently used. The yellow line of kyrpton is at an ideal wavelength to avoid absorption by xantophyll, which occurs in older crystalline lenses and in the macula. The red line of krypton, like that of the ruby laser, penetrates blood layers, and is thus useful for photocoagulations in layers below those of superficial vascularization. Unlike ruby, the krypton laser is stable in time and across the beam profile. This research is designed to evaluate the three krypton wavelengths, in comparison to argon light, and among themselves. Work will be carried out with Monkeys and with Clinical patients. Evaluations will involve flicker perimetry and focal ERG and VER, as well as the standard clinical and (for the animals) histological evaluations. A Reflectometer will be added to the laser photocoagulator, to evaluate reflectance of the photocoagulation light as a measure of degree of burn. Ultimately, this will be used to provide automatic control of the photocoagulator power during multiple-burn therapy.