Figure 1.

(A) In this semithin section, ganglion cell density, a closely packed monolayer to the left and becoming bilayered to the right, show that the electron microscopy tissue block is from the outer perifovea. Vacuoles can be seen in all retinal layers, with empty spaces most noticeable within the inner nuclear layer. The subretinal debris is seen to the right of the image (arrows). With the exception of a single anteriorly migrated cell (arrowhead), the retinal pigment epithelium (RPE) remains a monolayer, despite the large amount of overlying debris. Small pigment epithelial detachments are seen on low power (centre and left). (B) Vacuolar change is present in outer nuclear photoreceptor cell bodies and nuclei, as well as in the outer plexiform layer in the perifovea (asterisks). At this magnification, the subretinal debris appears to consist of shed photoreceptor outer segments (arrows) in contact with the apical membranes of the RPE. The arrowhead identifies the subretinal space. (C) Higher magnification of the subretinal debris shows little RPE reaction, with a single anteriorly migrated RPE cell. There is minimal RPE hypertrophy or hyperpigmentation. (D) The RPE plasma membrane (black arrowhead) is separated from its basement membrane (white arrowhead) by empty space, probably originally containing fluid, giving rise to the pigment epithelial detachments seen on low power in (A). In a minority of instances, the RPE is separated from its basement membrane by irregular basal foldings of its plasma membrane (inset). Bruch's membrane in the perifovea appears unremarkable. (D) Intracytoplasmic vacuoles suggestive of autophagy within RPE from the mid-periphery. Again, no abnormalities are seen within Bruch's membrane in the mid-periphery.