Objective To observe the location of the watershed zones of the choroidal blood supply relative to the optic disc in glaucoma by indocyan ine green angiography, and to investigate the mechanisms in the development of glaucomatous neuropathy. Method Simultaneous ICGA and FFA were performed on 31 eyes of 31 patients with glaucoma (17 of POAG, 14 of NTG) and 37 eyes of 37 control subjects. The watershed zones were classified into three types according to their location relative to the optic disc: by type I, no water shedzone around the optic disc; type II, the optic disc surrounded partially by watershed zone; type III, the optic disc surrounded completely by watershed zone. Each of the watershed zone types was scored (i.e., type I=1, type II=2, type III=3). Results In 87.1% of the glaucomatous eyes , the watershed zones included or partially included the optic disc. However, the figure in the control group was 56.8%. The glaucoma group had a higher score of watershed zone type than the control group. Conclusions The mechanisms in the development of glaucomatous neuropathy are correlative to the choroidal blood supply around the optic disc. (Chin J Ocul Fundus Dis，2004，20：218-220)