Confocal Microscopy and Timing for Silicone Oil Extraction

Abstract

Abstract: : Purpose: We analyzed pachymetry and endothelial features associated with intraocular silicone oil by using confocal microscopy tecniques. Methods: Group A: 16 eyes of 15 patients ( 25 to 71 years) undergoing intraocular silicone oil injection (Oxane® 1300, Bausch&Lomb) and Group B: 15 eyes of15 patients (21–74 years) undergoing intraocular heavy silicone oil injection (Oxane® Hd) were examined with corneal confocal microscopy, The items selected of the operated eyes were compared to the fellow eye if possible or to the normal values according to age (Group C). The duration of the tamponade ranked from 1 to 22 months. The parameters evaluated by an independant observer were: –Patient age –Cataract surgery –Number of surgical procedures –Presence of silicone droplets in endothelial layers –Endothelial cell population density –Pleomorphism –Corneal thickness –Presence of band keratopathy or bullous corneal edema –Presence of emulsified silicone oil in anterior chamber –Evolution after silicone oil removal Results: 14 out of 16 patients in group A and 13 out of 15 in group B showed psudonucleus or small high reflective structures at the endothelium. Only one patient in group C showed this picture. No changes in pachymetry were observed. The mean endothelial cell density was 1294.68 cell/mm² in group A, 1377.16 cell/mm² in group B and 2178.48 cell/mm² in group C. Endothelial cell loss was exacerbated in eyes undergoing long–term endotamponade and might be related to number of surgeries, iris–crystalline lens complex integrity and presence of silicone oil in the anterior chamber. Conclusions: Silicone oil may induce changes in human corneas, although sometimes no corneal finding indicating keratopathy is detected by slit–lamp microscopy. The corneal features observed with confocal microscopy may be an indirect tool in determining the timing for silicone oil extraction, assisting to avoid endothelial damage associated with long term silicone oil vitreous fill.

Keywords: microscopy: confocal/tunneling • vitreous substitutes • cornea: endothelium