• Carbon dioxide laser photocautery was used successfully intraocularly in human patients to seal fibrovascular fronds and retinal tears at the time of vitrectomy. Closure of rubeotic vessels in the iris was demonstrated histologically. The 10.6-μ infrared radiation was delivered to the intraocular treatment site by means of a 1.5-mm-diameter photocautery probe containing a 1.0-mm-diameter lumen closed at the end with an infrared transmitting window. Treatment was localized to the tissue adjacent to the window. Typical energy dosage was 0.4 W for 2 to 4 s duration. These early clinical trials were carried out under the guidelines established by the Food and Drug Administration; informed consent clearly outlined the experimental nature of these studies.