In a series of experimental animals, the usefulness of cryotherapy, diathermy, and photocoagulation in performing full-thickness eye wall resection was evaluated. Prolonged application of freezing caused phthisis bulbi, whereas the eyes did not become phthisical when cryocoagulation was applied for a short time. However, the effect of brief cryocoagulation was not intense enough to occlude vessels or to prevent vitreous hemorrhage. Prophylactic photocoagulation four weeks prior to surgery, combined with diathermy at the time of operation, with or without cryotherapy, was effective in minimizing vitreous hemorrhage and in preventing retinal detachments. This modification of the resection technique permits trephination of the eye wall and histologic examination of the resected area.