Retinal vessel photocoagulation: a quantitative comparison of argon and krypton laser

Retinal arteries of owl monkeys were photocoagulated with single exposures to argon laser green light (514 nm), krypton laser green light (531 nm), and krypton laser yellow light (568 nm). The distribution of damage along the vessel in different retinal layers was characterized geometrically after serial sectioning of the histopathologic material. Krypton laser radiation (green and, to an even greater extent, yellow) produced measurably greater effects on retinal vessels and adjacent structures than on deeper retinal levels; argon laser radiation (green) produced greater effects on the pigment epithelium. Krypton yellow produced the greatest total effect. The location of damage to the retinal arteries and pigment epithelium differed, with the peak of the damage around the arteries being farther from the optic disc than was the peak of the pigment epithelial damage.