(
A) En bloc photograph of a large area of capillary dropout extending from the optic disc (
) to fovea in diabetic monkey 9. An apparent cilioretinal vascular system (
arrow) is still viable. At higher magnification (
B), it is apparent that blood vessels temporal to the fovea were viable (have ADPase activity), whereas blood vessels central to fovea were not viable. A section through the fovea (
C) of the retina in (
A) showed fairly normal-appearing retina temporal to fovea (
left), whereas retina nasal to the fovea (
right) had outer atrophy, disruption, and loss of the photoreceptor nuclei in the outer nuclear layer (
arrow). Higher magnification of retina temporal to fovea (
D) demonstrated normal stratification of the retina and viable nuclei in both nuclear layers, but there was a paucity of ganglion cells. Inner retinal neuronal atrophy in a section nasal to fovea (
E) demonstrated loss of ganglion cells and inner nuclear layer neurons, whereas many photoreceptor nuclei appeared viable. PAS-positive tubes in the inner retina (
arrows) are the vestiges of blood vessels. (
F) Area in macula of diabetic monkey 14 shows large central nonperfused region with serous-filled cysts in the outer retina (∗). Section from a large nonperfused area in monkey 9 (
G) from an area adjacent to the area in (
E) shows outer retinal atrophy (
arrow), loss of photoreceptor nuclei, and disruption of the outer nuclear layer. (
A,
B) Lead ADPase reaction product with dark-field illumination; (
C–
G) sections stained with PAS and hematoxylin.