Retinal fluorescein angiography was used to examine the ocular fundi of 84 divers. The retinal capillary density at the fovea was low and microaneurysms and small areas of capillary nonperfusion were seen. The divers had significantly more abnormalities of the retinal pigment epithelium than a comparison group of non-divers. Furthermore, the prevalence of fundus abnormality was related to length of diving history. All observed changes were consistent with the obstruction of the retinal and choroidal circulations. Such obstruction could be due either to intravascular bubble formation during decompression, or to altered behaviour of blood constituents and blood vessels in hyperbaric conditions.