High-Resolution Spectral-Domain Oct (sd-oct) Imaging in Central Areolar Choroidal Dystrophy (cacd)

Abstract

Purpose: : To describe retinal ultrastructure of central areolar choroidal dystrophy (CACD) using high-resolution, spectral-domain optical coherence tomography (SD-OCT) as compared to geographic atrophy (GA) due to age-related macular degeneration (AMD).

Methods: : Simultaneous SD-OCT and fundus autofluorescence (FAF) were obtained for 40 CACD patients with the p.Arg142Trp peripherin/RDS gene mutation. Morphological alterations on SD-OCT were analyzed and classified in different CACD FAF stages and compared to GA. If atrophy was present the thickness of the choroid was measured by image analysis software.

Results: : In stage I SD-OCT showed subtle changes including focal thickening and irregular reflectivity of photoreceptor outer segment-retinal pigment epithelium (POS-RPE) interdigitations. Those changes were infrequently co-localized with FAF changes. In stage II we observed an increased distance between the inner photoreceptor segments and the POS-RPE band and thickening of RPE/Bruch’s membrane. In stage III and IV, the atrophic zone was characterized by loss of the outer retina up to the external limiting membrane and thinning of RPE/Bruch’s membrane complex. Atrophic areas were bordered by disrupted and swollen outer retina with reflectivity loss and retinal elevation. Beneath this retinal elevation, rosette and plaque-like structures were observed similar to GA. However, in contrast to GA, drusen-like deposits in the subpigmentepithelial space were not present. There was no obvious choroidal thinning on SD-OCT beneath the atrophic areas in CACD.

Conclusions: : In contrast to GA, morphologic changes in CACD were less variable and less complex compared to AMD eyes. In early stages of CACD major changes were identifiable on FAF but only minor changes were observed on SD-OCT. There was progressive outer retinal damage in advanced stages of CACD with eventual loss of the outer retina in the atrophic zone. Our findings indicate that CACD may represent a primary RPE disease with secondary neurosensory retinal involvement and without relevant choroidal alterations.

Keywords: degenerations/dystrophies • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid