No one imaging tool fits all in identifying AMD lesions

Reviewed by David Sarraf, MD

Multimodal imaging, including traditional and newer techniques, is necessary for identifying the spectrum of retinal lesions associated with age-related macular degeneration (AMD), said David Sarraf, MD.

In a review of the application of the different diagnostic modalities that can be used to characterize AMD-related pathologies, Dr. Sarraf, clinical professor of ophthalmology, Stein Eye Institute, UCLA, Los Angeles, indicated that large drusen (>125 µm), which are a defining feature of intermediate AMD, are best detected with spectral domain optical coherence tomography (SD-OCT).

SD-OCT is also essential for identifying reticular pseudodrusen, subretinal drusenoid deposits lying above the retinal pigment epithelium (RPE), Dr. Sarraf explained. Stage 1 reticular pseudodrusen are located underneath the ellipsoid zone and display a ribbon appearance with a hyper-autofluorescent ring, whereas the advanced stage III form illustrates a dot appearance and extend across the inner segment ellipsoid band.

These images illustrate the "ribbon" and "dot" forms of reticular drusen detected with spectral domain optical coherence tomography and fundus autofluorescence. (Images courtesy of David Sarraf, MD).

Drusenoid pigment epithelial detachments (PEDs) are large drusen (> 250 µm in diameter) that exhibit hyperfluorescent staining with fluorescein angiography but are hypofluorescent with indocyanine green (ICG) angiography. On SD-OCT, drusenoid PEDs display a discrete elevation of the RPE with homogenous hyperreflectivity under the RPE monolayer.

“These lesions have a very high risk for progression to geographic atrophy (GA),” Dr. Sarraf said. “The development of choroidal hypertransmission or a serous component within the PED typically heralds the evolution to the GA form.”

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