Purpose:
To analyze the retinal pigment epithelium (RPE) morphology and RPE cell density (RPECD) changes in flat-mounted human eyes with dry age-related macular degeneration (AMD), and evaluate the correlation of confocal images with histologic findings.
Methods:
Sixteen postmortem eyes (10 Dry AMD eyes, 6 normal eyes) from Georgia EyeBank were microdissected. The tissues were flat-mounted, stained with AF635-phalloidin, imaged using confocal microscope, and evaluated by Cellprofiler. After imaging, samples were re-embedded in paraffin and serially sectioned. Histologic findings were then reconstructed in a scaled 2-dimensional map.
Results:
16 human eyes with a mean death to preservation time 20.8±8.5 h from 8 donors (4 females, 4 males) with an average age of 81.3±10.4 years were evaluated. The mean RPECD of AMD eyes was 1267±862(center) and 3830±623 (periphery)cells/mm2; the RPECD of normal eyes was 4775±497 (center) and 3625±411 (periphery) cells/mm2 . The central RPECD significantly differed between dry AMD eyes and age-matched normal eyes (p<0.001). A few small hard drusen were present in the periphery of both AMD and normal eyes. In the macular region of AMD eyes, diffuse soft drusen, holes in the RPE sheet, and large multinucleate RPE were observed. In these areas, rosette structures where RPE have re-shaped to fill in space where neighbor cells have died were present. Increases in cell size, increases in variability in cell size, disruptions of cell form, and changes in the number of neighbors of RPE in AMD eyes were quantified.
Conclusions:
Microdissected ex vivo flat-mounts stained with phalloidin offers a valuable tool for RPE studies in normal and diseased human eyes. The RPECD differs with regard to anatomic location and is decreased in dry AMD. Confocal images show various types of drusen, geographic atrophy of the RPE, and redistribution of RPE in AMD that correlate with histologic features and 2-dimensional mapping.
Keywords: age-related macular degeneration • retinal pigment epithelium • pathology: human