Purpose:
To describe a new method for identifying the presence and distribution of intraretinal pigment clumps derived from retinal pigment epithelial cell migration using SDOCT imaging.
Methods:
Patients with the diagnosis of age-related macular degeneration (AMD) were enrolled in a prospective SDOCT imaging study. Patients were followed for a minimum of 6 months. Eyes were imaged using the 200x200 A-scan raster pattern (Cirrus HD-OCT, Carl Zeiss Meditec)) centered on the fovea. En face images were obtained by summing the OCT intensities in a region bounded by the retinal pigment epithelium (RPE) segmentation line and a line parallel to the RPE segmentation line but located at distances of 40 µm, 60 µm, 90 µm and 120 µm above it. A second set of en-face images was obtained by translating each of these regions upwards by 20 µm.
Results:
A total of 16 eyes with drusenoid detachments of the RPE were included in this study. Mean follow-up was 23.8 months. The drusenoid RPE detachments persisted in 8 eyes (50%), evolved to geographic atrophy (GA) in 5 eyes (31.25%), developed CNV in 2 eyes, and resolved without formation of GA or CNV in 1 eye. During follow-up, retinal pigment was observed on exam, color fundus imaging, and SDOCT imaging in 9 out of 16 eyes (56.3%). Intraretinal pigment clumping was observed in all 5 eyes developing GA, in 2 out of 8 eyes with persistent RPE detachments, in one eye developing CNV, and in the one eye with resolution of the PED in the absence of obvious disease progression. Intra-retinal pigment was observed in all en face images of the same patient. Images obtained by shifting the RPE contour by 20 µm and using a slab thickness of 40 µm and 60 µm provided the best visualization of the pigment.
Conclusions:
SDOCT en face imaging can provide qualitative assessment of pigment clumps within the central macula by using a slab based on the RPE segmentation contour but shifted 20 µm above the actual RPE boundary. The exclusion of the RPE and the photoreceptor IS/OS junction from these images may be responsible for the better contrast and identification of the pigment clumps.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)