Purpose
Intravitreal injection of anti-VEGF antibodies has proven successful in treating neovascular age-related macular degeneration (AMD). However, some treated patients develop vision loss after regression of choroidal neovascularization (CNV) due to changes in the retinal pigment epithelium (RPE) that clinically resemble geographic atrophy (GA). To understand whether this form of RPE atrophy is distinct from GA, we examine its microscopic features in vivo.
Methods
An 83-year-old patient with neovascular AMD who developed an atrophic RPE lesion after anti-VEGF injections underwent comprehensive eye examination and conventional imaging including fundus photography and fundus autofluorescence (FAF, Heidelberg Retina Angiograph). Adaptive optics scanning light ophthalmoscopy (AOSLO) was used to image the photoreceptor and RPE cells simultaneously. Near-infrared light (796 nm) was used to image photoreceptors; intrinsic autofluorescence (AF) of lipofuscin was exploited to image RPE cells (excitation 532 nm; emission 650 Δ 150nm), using light levels more than 20 times below the ANSI maximum permissible exposure. Images were obtained within, at the margin, and outside of the lesion area. Two imaging sessions were conducted, three weeks apart.
Results
AOSLO reflectance imaging within the lesion showed cellular structures of a size and distribution consistent with cone photoreceptors. These cells did not exhibit the temporal variations in reflectivity characteristic of normal healthy cones. Fluorescence AOSLO imaging within the lesion showed collections of AF, not detected by conventional FAF, measuring 20-30 microns in diameter. Hyperautofluorescence was present just outside the lesion margin, and patterns of abnormal AF continued well outside the lesion.
Conclusions
AOSLO demonstrates that cones appear to be present, but injured, within areas of RPE atrophy after anti-VEGF antibody injections. The sparse collections of AF within the atrophy may represent enlarged, lipofuscin-laden RPE cells. These findings suggest that RPE atrophy developing after anti-VEGF therapy may be distinct from GA.
Keywords: 412 age-related macular degeneration •
701 retinal pigment epithelium •
550 imaging/image analysis: clinical