Figure 4.

Assessing Photoreceptor and RPE Health in RPE65-IRDs

(A) SD-OCT total thickness topography (left) and near infrared fundus autofluorescence (NIR-FAF) in an RPE65-IRD patient. Overlaid dotted line defines area with detectable photoreceptors by inspection of individual SD-OCT cross-sections that may be targeted by the subretinal injection or bleb. Inset: normal NIR-FAF. f, fovea. (B) SD-OCT, 6-mm-long cross-sections through the fovea before treatment. Nuclear and outer sublaminae are labeled as in Figure 2. Inset: near infrared reflectance (NIR-REF) image with an overlaying arrow to show the position and orientation of the scans. Scale bar (bottom left), 200 μm. The ONL thickness in cross-section does not accurately match the thickness topography. The red arrow in (A) points to a thicker (warmer color) parafoveal region that does not match the even and symmetrical decline in ONL thickness with distance from the fovea into the nasal and temporal retina demonstrated in the SD-OCT cross-section in (B), suggesting, in the absence of cystoid edema, inner retinal thickening due to secondary inner retinal remodeling. A faint NIR-FAF signal near the center surrounded by background choroidal autofluorescence corresponds in lateral extent with a region of clearly detectable RPE/Bruch’s membrane (BrM), photoreceptor ONL, and EZ signals on the SD-OCT cross-section (diagonal white arrows). A very thin ONL can be traced away from the foveal center into the pericentral retina, well beyond the area of relative preservation of RPE and photoreceptors. Note the hyporeflective space between the EZ and RPE/BrM band at the foveal center that likely corresponds with sparsely distributed and shorter cone photoreceptor outer segments.