The Nature of Chorioretinal Lesions Pro- Duced by the Gallium Arsenide Laser. 0

has reported similar observations in a human case of postganglionic Homer's syndrome. The clinical application of long posterior ciliary canal cautery has met with equivocal success in the treatment of glaucoma.' °~ We have found it clinically ineffective in secondary glaucoma. Histologic sections of two such eyes did not reveal closure of the long posterior ciliary arteries one month after treatment. From our experimental results it is clear that closure of the long posterior ciliary vessels is difficult to obtain by cautery in primates. This appears due to difficulty in localizing the vessels, their depth in the suprachoroid, and impermanence of vessel closure. The significant reduction of intraocular pressure noted for at least four weeks in this study is believed to be due to a reduction in blood flow to the ciliary body. The extent to which sympathetic denervation contributed to this intraocular pressure lowering effect is under investigation.