Abstract
Purpose: :
To describe the features of 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 dry age-related macular degeneration (AMD), and to correlate RPE migration on OCT to RPE pigment clumping on fundus photographs.
Methods: :
A prototype high speed ultrahigh resolution OCT device, capable of 3.5 um axial resolution and 25,000 A-scans per second, was used to image 55 eyes of 44 patients with dry AMD in the eye clinic. 3D OCT scan sets (512 A-scans/image, 180 images/set) from all patients were analyzed for the presence of RPE migration, defined as small discreet hyper-reflective and highly-backscattering lesions within the neurosensory retina overlying disturbances of the RPE layer. Individual OCT scans were then examined to determine which intraretinal layer the pigment had migrated to, and whether drusen were present underneath areas of pigment migration.All color fundus photographs were also analyzed to determine the presence of RPE pigment clumping, defined as black-colored, spiculated areas of pigment clumping within the macula. OCT en face images, created via summation of axial OCT data, were correlated with color fundus photographs to demonstrate correspondence of RPE migration on OCT and RPE clumping on fundus photos.
Results: :
54.5% of eyes (30/55) demonstrated RPE migration on OCT scans. 56.4% of the color fundus photographs (31/55) demonstrated RPE pigment clumping. All eyes with RPE migration on OCT had corresponding RPE pigment clumping on color fundus photographs. RPE pigment migrated most frequently into the outer nuclear layer (66.7%) and less frequently into more anterior retinal layers. It was also noted that RPE migration mainly occurred above areas of drusen (73.3%).
Conclusions: :
The appearance of RPE migration on OCT is a common occurrence in patients with early to mild dry AMD, occurring in 54.5% of eyes examined. The area of RPE migration on OCT always correlated to areas of pigment clumping on fundus photography. Conversely, all but one eye with RPE pigment clumping on fundus photography also had areas of RPE migration on OCT. The high number of RPE migration observed above areas of drusen suggests that drusen may play a physical and/or a catalytic role in facilitating RPE migration.
Keywords: age-related macular degeneration • imaging/image analysis: clinical • retinal pigment epithelium