Appearance of Regressing Drusen on Optical Coherence Tomography in Age-related Macular Degeneration

Abstract

To describe and interpret a multilaminar sub-retinal pigment epithelium (RPE) intense hyper-reflectivity observed invivo in eyes clinically diagnosed with regressing drusen. Observational case series. Twenty-three consecutive patients clinically diagnosed with regressing calcific drusen due to nonneovascular age-related macular degeneration (AMD). Patients were submitted to confocal scanning laser ophthalmoscopy (cSLO) fundus imaging and "eye-tracked" spectral-domain optical coherence tomography (SD-OCT). Localization and possible origin and composition of the multilaminar sub-RPE hyperreflectivity. Thirty eyes of 23 consecutive patients (8 male and 15 female; mean age, 82.7±10.1 years) showing on SD-OCT an intense multilaminar sub-RPE hyperreflectivity, which matched with regressing calcific drusen as visualized by cSLO infrared (IR) and MultiColor (Heidelberg Engineering, Heidelberg, Germany) images, were included in this study. The multilaminar hyperreflectivity was found to localize to beneath the RPE and above the outer Bruch's membrane (oBM) layer. A mean of 1.2 multilaminar sub-RPE hyperreflectivities per SD-OCT scan were identified by 2 readers. The SD-OCT analysis allowed the 2 readers to describe 3 different types of sub-RPE hyperreflectivity. "Type 1" laminar/multilaminar hyperreflectivity (found in 24 scans of 12 eyes) was characterized by an intense signal originating from what we interpreted as the inner Bruch's membrane (iBM) layer. "Type 2" multilaminar hyperreflectivity (found in 130 scans of 27 eyes) was characterized by an intense signal originating from the oBM layer. "Type 3" multilaminar fragmented hyperreflectivity (found in 22 scans of 11 eyes) was characterized by an intense signal originating from what we interpreted as both the iBM and the oBM, showing different degrees of fragmentation. We describe a novel SD-OCT finding appearing as multilaminar sub-RPE intense hyper-reflectivity observed invivo in eyes with regressing drusen. This multilaminar sub-RPE hyperreflectivity could beinterpreted as layers of lipid mineralization (membranous debris also called "lipoprotein-derived debris" developing calcification), internal and external to the basement membrane, with different degrees of fragmentation.