Documentation of intraretinal retinal pigment epithelium migration via high-speed ultrahigh-resolution optical coherence tomography

Purpose: To describe the features of intraretinal retinal pigment epithelium (RPE) migration documented on a prototype spectral-domain, high-speed, ultrahigh-resolution optical coherence tomography (OCT) device in a group of patients with early to intermediate dry age-related macular degeneration (AMD) and to correlate intraretinal RPE migration on OCT to RPE pigment clumping on fundus photographs.

Design: Retrospective, noncomparative, noninterventional case series.

Participants: Fifty-five eyes of 44 patients seen at the New England Eye Center between December 2007 and June 2008 with early to intermediate dry AMD.

Methods: Three-dimensional OCT scan sets from all patients were analyzed for the presence of intraretinal RPE migration, defined as small discreet hyperreflective and highly backscattering lesions within the neurosensory retina. Fundus photographs also were analyzed to determine the presence of RPE pigment clumping, defined as black, often spiculated, areas of pigment clumping within the macula. The en face OCT images were correlated with fundus photographs to demonstrate correspondence of intraretinal RPE migration on OCT and RPE clumping on fundus photography.

Main outcome measures: Drusen, dry AMD, intraretinal RPE migration, and RPE pigment clumping.

Results: On OCT scans, 54.5% of eyes (61.4% of patients) demonstrated intraretinal RPE migration. Of the fundus photographs, 56.4% demonstrated RPE pigment clumping. All eyes with intraretinal RPE migration on OCT had corresponding RPE pigment clumping on fundus photographs. The RPE pigment migrated most frequently into the outer nuclear layer (66.7% of eyes) and less frequently into more anterior retinal layers. Intraretinal RPE migration mainly occurred above areas of drusen (73.3% of eyes).

Conclusions: The appearance of intraretinal RPE migration on OCT is a common occurrence in early to intermediate dry AMD, occurring in 54.5% of eyes, or 61.4% of patients. The area of intraretinal RPE migration on OCT always correlated to areas of pigment clumping on fundus photography. Conversely, all but 1 eye with RPE pigment clumping on fundus photography also had areas of intraretinal RPE migration on OCT. The high incidence of intraretinal RPE migration observed above areas of drusen suggests that drusen may play physical and catalytic roles in facilitating intraretinal RPE migration in dry AMD patients.