Primates underwent the ab interno removal of up to a 6 X 7-disc diameter area of the retina and choroid adjacent to the optic disc. The area of resection was treated three weeks before surgery with an encircling row of xenon arc photocoagulation. Surgery involved photocoagulation of the entire resected area and removal of the retina and choroid using a wide-angle cutter vitrophage. Vitreous fluid was replaced in 50% of the eyes with sodium hyaluronate (Healon). The majority of eyes in which the vitrectomy fluid was replaced with saline solution became phthisical. All but one eye containing sodium hyaluronate recovered preoperative intraocular pressures and maintained the integrity of the remaining intraocular structures.