Congenital Hypertrophy of the Retinal Pigment Epithelium: Enhanced-Depth Imaging Optical Coherence Tomography in 18 Cases

Abstract

To describe the imaging characteristics of congenital hypertrophy of the retinal pigment epithelium (CHRPE). Retrospective, observational case series. Eighteen eyes of 18 patients with CHRPE. Review of chart, fundus photography, ultrasonography, fundus autofluorescence, infrared reflectance (IR) imaging, and enhanced-depth imaging optical coherence tomography (EDI-OCT). Features of CHRPE as analyzed by EDI-OCT. The mean age at diagnosis was 48 years (range, 13-73 years). There were 5 males and 13 females, and 17 Caucasian and 1 African American patients. The mean best-corrected visual acuity was 20/22 (range, 20/20-20/40). The CHRPE was located in the retinal periphery (n= 16) with intralesional lacunae (n= 14) and surrounding nonpigmented (n= 4) and pigmented (n= 14) halo. By ultrasonography, the mean CHRPE thickness was 1.0 mm (range, 0.9-1.4 mm). Fundus autofluorescence disclosed hypoautofluorescence (n= 18) with lacunae (n= 14) showing isoautofluorescence (n= 10) or hypoautofluorescence (n= 4). Infrared reflectance imaging displayed hyporeflectivity in the area of pigmentation (n= 16) and hyperreflectivity within lacunae (n=14). On EDI-OCT, all 18 lesions were flat with a mean basal diameter of 4529 μm (median, 3707 μm; range, 697-11 617 μm). The mean central sublesional choroidal thickness (126.4 μm) was not different compared with thickness 50μm outside the margin (126.8 μm; P= 0.99). The retinal pigment epithelium (RPE) was absent (n=2), thickened (n= 16), or irregular (n= 15). Of 9 lesions in which lacunae were imaged, 8 showed absent RPE. The overlying retinal findings included thinning or absence of the outer retina beginning at the ganglion cell layer (n= 1), outer plexiform layer (n= 4), outer nuclear layer (n= 12), or inner segment/outer segment junction (n= 1). Additional retinal findings included hyperreflective spots (n= 11), cystoid edema (n= 5), and subretinal cleft (n= 6). Subretinal cleft specifically occurred at the site of absent photoreceptors. Generally, CHRPE displays hypoautoflouorescence and hyporeflectivity with hyperreflective lacunae on IR imaging. On EDI-OCT, CHRPE seems flat with thickened, irregular RPE and absent RPE within lacunae. A prominent feature is outer retinal loss, generally involving the outer nuclear layer to photoreceptors, occasionally with a characteristic subretinal cleft.