Experimental evaluation of a synthetic viscoelastic material on intraocular pressure and corneal endothelium

We compared the effects of 1.0% hyaluronic acid (Healon) and a synthetic viscoelastic polyacrylamide on postoperative intraocular pressure, the corneal endothelium, and various clinical parameters in rabbit and monkey models. Seven rabbit eyes received polyacrylamide and seven received hyaluronic acid during extracapsular cataract extraction with implantation of a polymethylmethacrylate posterior chamber intraocular lens. Intraocular pressure was measured preoperatively, immediately postoperatively, and at 1, 2, 4, 8, 12, and 24 hours postoperatively. Slitlamp examination was performed preoperatively and postoperatively at 3, 7, and 14 days. Axial corneal buttons were taken and scanning electron microscopy of the endothelium was performed. Sections of the globe were studied by light microscopy. Six monkey eyes received polyacrylamide, three received hyaluronic acid, and three received balanced salt solution to reform the anterior chamber after limbal incision with evacuation of aqueous. Intraocular pressure was measured preoperatively, postoperatively, and at 4, 8, 12, 24, and 48 hours postoperatively. Slitlamp examination was performed preoperatively, and at 1, 2, 7, and 14 days postoperatively. Specular endothelial microscopy was performed preoperatively and at 7, 14, and 90 days postoperatively. In the studies performed no significant difference between the eyes receiving polyacrylamide and hyaluronic acid was seen. In the rabbit and monkey models, polyacrylamide is as safe and biocompatible as hyaluronic acid.