Effects of the CW YAG laser on the human iris and retina.

A CW YAG laser was used to coagulate retina and to produce an optical iridotomy in a human eye that was to be enucleated for malignant melanoma at the optic nerve head. Moderate coagulation with the CW YAG laser produced a deep choroidal reaction involving the outer portion of the retina. The inner structure of the fovea remained relatively unaffected. The nerve fiber over the coagulated vessels was unchanged. An optical iridotomy also was produced with the CW YAG. At least ten times more energy was needed to produce retinal photocoagulation with the CW YAG than is generally needed with the argon laser. Retrobulbar anesthesia should be used to prevent pain if extensive coagulation is done.