Fig. 3.

Optical coherence tomography (OCT) of lesions 1–6 in the two monkeys. 24 h. Initial OCTs were obtained 24 h post-lesion, and show 3 lesions in each monkey on either side of the foveal pit near the center of the lesions. Altered OCT signal extends from the retinal pigment epithelium (RPE) to the outer nuclear layer, apparently tracking photoreceptor pedicles (Henle fibers), which project to bipolar cells that are displaced away from the fovea center. >6 mo. Composite OCTs are shown for each monkey, since the visibility of 6 mo. OCTs varied across individual B scans. Most lesions at this time show a gap in OCT signal from the region of photoreceptor inner and outer segments, as well as partial collapse of the outer nuclear layer (ONL), consistent with a loss of photoreceptor nuclei in the central portion of most lesions examined histologically (Figs. 4 and 5). The images >6 mo were obtained with “Selective Pixel Profiling” software (Zeiss, Jena), a method that reduces speckle noise in OCT images, and was not available when the 24 h images were obtained. This improvement in the OCT software does not affect system resolution.