Functional recovery of retinal pigment epithelial damage in experimental retinal detachment

The integrity of the RPE barrier function in retinal detachment was studied in vitro. The retinal pigment epithelium (RPE)-choroid tissue was isolated from cynomolgus monkey eyes with acute (less than 1 hr), subacute (1-2 weeks), and chronic (8-20 months) retinal detachments, and clamped between Ussing-type chambers. Electrical characteristics and choroid-to-retina permeability to carboxyfluorescein were determined. In the HEPES-buffered bathing solution, transepithelial potential difference and resistance in eyes with acute retinal detachments (0.2 mV and 134 ohm-cm2, respectively) were significantly lower than subacute (7.9 and 350) and chronic (10.4 and 348) retinal detachments. Furthermore, the permeability was increased five-fold in acute retinal detachments with respect to subacute and chronic retinal detachments, indicating a breakdown of the RPE barrier in acute retinal detachment. No statistical difference was found between subacute and chronic retinal detachments. In this animal model, RPE barrier function is destroyed at the onset of retinal detachment, but recovers in a week or two, and is maintained in the chronic stage. Histological examination revealed that RPE recovery was accomplished by RPE proliferation and hyperplasia.