Abstract
PurposeTo describe and quantify Bruch's membrane (BM) and retinal pigment epithelium (RPE) separation using spectral-domain (SD) optical coherence tomography (OCT) in patients affected by inherited macular degenerations associated with BM thickening.MethodsPatients with molecularly confirmed Sorsby fundus dystrophy (SFD), dominant drusen (DD), and late-onset retinal degeneration (L-ORD) were included in this retrospective study. Each disease was classed as early stage if subjects were asymptomatic, intermediate stage if they had nyctalopia alone, and late stage if they described loss of central vision. The main outcome was measurement of BM-RPE separation on SD-OCT. The BM-RPE separation measurements were compared against those in normal age-matched controls.ResultsSeventeen patients with SFD, 22 with DD, and eight with L-ORD were included. BM-RPE separation on SD-OCT demonstrated a high test-retest and interobserver reproducibility (intraclass correlation coefficients >0.9). BM-RPE separation was not identified in normal subjects. In SFD, there was greater BM-RPE separation in late-stage disease compared with intermediate-stage patients both at subfoveal (P < 0.05) and juxtafoveal (P < 0.01) locations. In DD, there was increased BM-RPE separation in late-stage disease compared with early stage at subfoveal (P < 0.001) and juxtafoveal (P < 0.05) topographies. There was no significant difference in BM-RPE separation between disease stages in L-ORD.ConclusionsBM-RPE separation is a novel, quantifiable phenotype in the three monogenic macular dystrophies studied, and may be an optical correlate of the histopathological thickening in BM that is known to occur. BM-RPE separation, as measured by OCT, varies with stage of disease in SFD and DD, but not in L-ORD.Translational Relevance SFD, DD, and L-ORD are associated with BM thickening. In this group of patients, OCT assessment of macular structure identifies a separation of the usually single, hyperreflective line thought to represent BM and the overlying RPE. This separation is a novel and quantifiable feature of disease staging in SFD and DD.
Highlights
TVST | May 2020 | Vol 9 | No 6 | Article 26 | 2
In Sorsby fundus dystrophy (SFD), there was greater Bruch’s membrane (BM)-retinal pigment epithelium (RPE) separation in late-stage disease compared with intermediate-stage patients both at subfoveal (P < 0.05) and juxtafoveal (P < 0.01) locations
In dominant drusen (DD), there was increased BM-RPE separation in late-stage disease compared with early stage at subfoveal (P < 0.001) and juxtafoveal (P < 0.05) topographies
Summary
Patients with molecularly confirmed Sorsby fundus dystrophy (SFD), dominant drusen (DD), and late-onset retinal degeneration (L-ORD) were included in this retrospective study. Bruch’s membrane (BM) is an acellular pentalaminar matrix located between the choroid and retinal pigment epithelium (RPE), extending from the edge of the optic disc to the ora serrate.[1,2] BM thickens with age[3] resulting in as much as a three-fold increase in thickness at the macula.[4,5,6,7,8] It has been suggested that BM thickening contributes to the development of pathology in diseases, such as age-related macular degeneration (AMD).[9,10,11,12]. Four hyperreflective lines are normally seen in the outer retina These lines have been labeled the external limiting membrane (ELM), ellipsoid zone (EZ), RPE interdigitating zone (IZ), and the RPEBM.[13] Usually, SD-OCT does not demonstrate resolvable BM separation from RPE except in marked pathology.[14,15]
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