Clinicopathologic correlation of localized retinal pigment epithelium debridement

To characterize changes in the retina, retinal pigment epithelium (RPE), and choriocapillaris with fluorescein angiography (FA) and histology after hydraulic or abrasive RPE debridement in 26 domestic short-haired cats.

Hydraulic debridement was produced by injecting balanced salt solution forcefully into the subretinal space. For abrasive debridement, RPE were removed with a silicone-tipped cannula after creating a localized retinal detachment. The FAs were performed after surgery, and tissue was prepared for light microscopy (LM) and scanning electron microscopy (SEM).

Sixty-seven blebs were examined by FA 1 hour after surgery, and RPE debridement was confirmed by SEM or LM in 15 blebs from 10 animals. Hyperfluorescence and variable central fluorescein leakage were seen 1 week after surgery in 52 of 53 blebs (which includes all 27 blebs from the 1-week timepoint and 26 of 29 blebs from the 4-week timepoint that were studied by FA 1 week after surgery). Choriocapillary filling delays were seen in no hydraulic debridements, but in 11 of 14 abrasive blebs, especially in areas showing leakage late in the angiogram. In 1 of 13 hydraulic and 12 of 14 abrasive debridements, areas of late dye leakage had no RPE with outer retinal degeneration. At the 4-week timepoint, 1 of 17 hydraulic and 10 of 12 abrasive debridements had foci of delayed or absent choriocapillary perfusion by FA, with degenerated outer retina, no RPE, and choriocapillary atrophy by histologic analysis.

Abrasive debridement is more commonly associated with abnormal FAs and with incomplete RPE repopulation, choriocapillaris atrophy, and outer retinal degeneration than is hydraulic debridement. This clinicopathologic study may give insight into FA interpretation after choroidal neovascular membrane removal in human patients.