Experimental use of space-retaining substances with extended duration: functional and morphological results

Background: In glaucoma surgery, e.g. cyclodialysis ab interno, to date no viscous substances have been available that stay in the cyclodialysis cleft long enough to prevent scarring. We examined the qualities of two different viscoelastic substances that stay longer in the place of instillation than hyaluronic acid. Methods: We performed cyclodialysis ab interno in 12 eyes of six owl monkeys. The right eyes were treated with the gel with the higher molecular weight, the left eyes using the gel with the lower molecular weight. The baseline data of intraocular pressure and outflow facility were compared to the values measured postoperatively up to the 140th day. Histological examination of the eyes followed. Results: There was no statistically significant difference between the two substances. The mean intraocular pressure decrease was 7.9 (±2.9) mmHg in the right eyes and 4.8 (±2.7) mmHg in the left eyes. The histological examination showed that the gel had remained in the cyclodialysis cleft without signs of inflammation. In contrast to other viscoelastic substances studied previously, the substances in this study performed their space-retaining function without decreasing outflow facility. Conclusion: Both substances are suitable means of improving the rate of success of cyclodialysis ab interno, as they remain where they are instilled long enough to prevent wound scarring in the cyclodialysis cleft.