Correspondence

Longitudinal Evaluation of the Development of Wedge-Shaped Subretinal Hyporeflectivity in Geographic Atrophy

The authors present the case of a 73-year-old woman affected by geographic atrophy (GA) in her left eye. During her follow-up, she developed a subretinal hyporeflective space visible on optical coherence tomography (OCT) images. This peculiar OCT sign was recognized to represent a wedge-shaped subretinal hyporeflectivity (WSSH). In contrast to previous reports showing that WSSH develops during the flattening of drusenoid pigment epithelium detachment (PED), the authors found that the WSSH manifestation may be even consecutive to the regression of a large PED and consequent GA appearance. Therefore, the origin of this peculiar OCT finding could be more complex and variegated. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:116-118.].

The Evolution of the Plateau, an Optical Coherence Tomography Signature Seen in Geographic Atrophy

Purpose

Histologic details of progression routes to geographic atrophy (GA) in AMD are becoming available through optical coherence tomography (OCT). We studied the origins and evolution of an OCT signature called plateau in eyes with GA and suggested a histologic correlate.

Methods

Serial eye-tracked OCT scans and multimodal imaging were acquired from eight eyes of seven patients with GA and plateau signatures over a mean follow-up of 7.7 years (range, 3.7–11.6). The histology of unrelated donor eyes with AMD was reviewed.

Results

Drusenoid pigment epithelial detachment (PED) on OCT imaging progressed into wide-based mound-like signatures with flattened apices characterized by a hyporeflective yet heterogeneous interior and an overlying hyperreflective exterior, similar to outer retinal corrugations previously ascribed to persistent basal laminar deposit (BLamD) but larger. These new signatures are described as “plateaus.” An initial increase of the PED volume and hyporeflectivity of its contents was followed by a decrease in PED volume and thinning of an overlying hyperreflective band attributable to the loss of the overlying RPE leaving persistent BLamD. Both imaging and histology revealed persistent BLamD with defects through which gliotic Müller cell processes pass.

Conclusions

Plateaus can be traced back to drusenoid PEDs on OCT imaging. We hypothesize that during progressive RPE atrophy, Müller cell extension through focal defects in the residual persistent BLamD may contribute to the heterogeneous internal reflectivity of these entities. The role of Müller cell activation and extension in the pathogenesis of AMD should be explored in future studies.