Débridement of the pig retinal pigment epithelium in vivo.

OBJECTIVE: To study the morphologic effects of surgical débridement of the retinal pigment epithelium (RPE) in an animal model.

METHODS: A pars plana vitrectomy was performed in the domestic pig, and a neurosensory retinal detachment was created by injecting the calcium-chelating agent edetic acid (commonly referred to as ethylenediaminetetraacetic acid or EDTA) into the subretinal space through a retinotomy. Twenty minutes later, the RPE was débrided by gently brushing Bruch's membrane with a soft-tip silicone catheter. Dissociated RPE was aspirated from the subretinal space, and the retina was reattached with a fluid-gas exchange.

RESULTS: Light microscopic analysis confirmed that Bruch's membrane was devoid of native RPE and the choriocapillaris was morphologically intact immediately after débridement. Photoreceptor outer segments were disrupted and foreshortened immediately after RPE débridement. One to 4 weeks later, a layer of hypopigmented RPE covered most of the previously débrided areas of Bruch's membrane. The choriocapillaris was intact in areas of Bruch's membrane that were repopulated by hypopigmented RPE, and remained intact 12 weeks after débridement. Some regions of Bruch's membrane near the retinotomy remained devoid of RPE for more than 4 weeks after débridement. The choriocapillaris was atrophic and there was extensive disruption of the outer retinal layers in these areas.

CONCLUSIONS: The RPE healed in most areas after surgical débridement of the RPE in the experimental animal. Atrophy of the choriocapillaris was present in areas of poor RPE healing near the retinotomy.