Characteristics of Retinal Pigment Epithelium Elevations Preceding Exudative Age-Related Macular Degeneration in...

Drusen and pigmentary abnormality are found as the hallmark to predict progression of age-related macular degeneration (AMD). In Asian populations, exudative AMD often appears in the absence of drusen but is rather accompanied by pigmentary abnormality. Recently, shallow irregular retinal pigment epithelium (RPE) elevations (SIRE) have been shown as a sign of subclinical nonexudative macular neovascularization. In this study, we aimed to investigate the characteristics of optical coherence tomography (OCT) findings including SIRE before the appearance of exudative AMD.

We retrospectively reviewed 32 cases of exudative AMD that occurred in the fellow eye within the 5-year-observation period. Color fundus photography, OCT, and fluorescein/indocyanine-green angiography at the beginning of observation and at the time when exudative AMD appeared were examined to diagnose SIRE and the subtype of exudative AMD.

Exudative AMD was found in 19 eyes with large drusen and 13 eyes without large drusen. Mean sub-foveal choroidal thickness without large drusen was significantly thicker than that with large drusen (336 ± 109 and 220 ± 96 μm, respectively; mean ± SD). Six eyes with pachychoroid neovasculopathy, 4 eyes with type 1 macular neovascularization, and 3 eyes with PCV had occurred in the fellow eye without large drusen. Among those, 6 eyes had been accompanied by SIRE with a greatest transverse linear dimension of 1 mm or more at the beginning of observation period. Besides, small RPE elevations with a longest diameter of less than 1 mm had been observed in other 5 eyes. Three cases of polypoidal choroidal vasculopathy had originated from small RPE elevations. Moreover, pachyvessels, choriocapillaris thinning, or choroidal hyperpermeability were observed with SIRE or small RPE elevations.

There is a non-drusen type of exudative AMD that originates from small RPE elevations as well as SIRE.