RETINAL DISTORTION AND COTTON WOOL SPOTS ASSOCIATED WITH EPIRETINAL MEMBRANE CONTRACTION

Purpose and Background: Several articles on surgery for macular pucker have noted the presence of intraretinal white spots, presumably cotto n-wool spots, associated with epiretinal membranes. It was proposed th at membrane contraction and resultant nerve fiber layer distortion mig ht lead to blockage of axoplasmic flow and thus a cottonwool spot. To see whether the observations supported this concept, the authors studi ed patients with epiretinal membranes associated with intraretinal whi te spots involving the center of the fovea, where there are normally n o retinal vessels and the only axons are in Henle fiber layer. Methods : Four patients with epiretinal membranes associated with prominent ar eas of intraretinal whitening involving the center of the fovea were e xamined before and after surgery. Observations and measurements were m ade from projected fundus photographs. Results: The intraretinal white spots, which appeared preoperatively to lie in the center of the fove a, proved to have been putted in from more peripheral retina by the ep iretinal membrane. These white areas were associated with surprisingly great distortion of the inner retina. Stretching of the inner retina seemed to play a larger role in the retinal distortion than full-thick ness retinal folding. Conclusion: The appearance and time course of th ese intraretinal white lesions were consistent with cotton-wool spots caused by mechanical disruption of axonal flow. The marked retinal str etching and distortion of the innermost layers of the retina were the most striking findings in this study and also seemed consistent with t he concept that membrane contraction and resultant nerve fiber layer d istortion might lead to blockage of axoplasmic flow and thus a cotton- wool spot.