Abstract
Abstract: :
Purpose:To investigate structural and functional changes in the retina following surgical induction of retinal detachment (RD) in the primate. Methods: Cynomolgus monkeys (2.6–4 kg) were anesthetized with ketamine and isoflurane. The surgery consisted of three–port core vitrectomy followed by induction of RD involving the fovea, using 42 g cannula for sub–retinal injection of balanced salt solution (BSS) either manually (n = 1) or using an automated pump (n = 3). A light pipe was used to illuminate these procedures. Two control procedures were done following the vitrectomy procedures: 1) BSS was injected and aspirated without leaving a bleb (n=2); and 2) the light pipe was held statically at 2 mm from the fovea for 30 minutes without sub–retinal injection of fluid (n=1). Changes in retinal structure and function were evaluated with FA, ICGA, OCT and mfERG (pre and post surgery at days 1, 3, 7, 14, 28, 60). Results: There was a spontaneous resolution of detachment by day 3 and the affected zone showed a mottled appearance (early hyper fluorescence increasing in the late phase) with an area of hyper pigmentation along the inferior border (blocked fluorescence) which persisted till day 60. The mfERG values at the fovea as well as the temporal macula were reduced to 30 % at day 1 and fully recovered by day 28. In control experiment #1, the fundus photos and FA showed similar persisting mottled appearance as RD. The mfERG values at fovea as well as the temporal macula were reduced to 30 % at day 1 and showed full recovery by day 7. In control experiment #2, the fundus photos showed a circumscribed mottled lesion around the fovea at 24hrs (early hyper fluorescence increasing in the late phase) that developed patchy appearance by day 14 (areas of blocked fluorescence with rim of hyper fluorescence). The mfERG values at superior para fovea were reduced to 60 % at day 1, whereas they were normal at fovea. These values were reduced to 30 % at both locations by day 7 and showed full recovery by day 28. Conclusions: Similar morphological and functional changes up to 4 weeks were seen in the primate retina following vitrectomy and retinal illumination with or without sub–retinal fluid or sham detachment. The discrepancy between persisting morphological changes and complete functional recovery could be important from clinical standpoint and requires further investigation.
Keywords: retinal detachment • electroretinography: non–clinical • vitreoretinal surgery