A new stainless steel spiral Schlemm's canal expander in surgical treatment open-angle glaucoma

PURPOSE: To evaluate the safety and effectiveness of Schlemm's canal (SC) dilation with stainless steel spiral Schlemm's canal expander (SCE) in decreasing intraocular pressure (IOP) in patients with open angle glaucoma (OAG). MATERIAL AND METHODS: Eighteen consecutive patients (18 eyes) with OAG, who's IOP was insufficiently controlled by their current ocular hypotensive medications were operated upon. A 4-5 mm long SCE made from 0.05 mm thick medical grade stainless steel wire was implanted into the SC lumen ab externo. In 6 cases with coexisting pathology a combined two site procedure - phacoemulsification with implantation of an intraocular lens (IOL) and SCE implantation was performed. Primary outcome measure was IOP change, secondary - number of glaucoma medications pre-and postoperatively and complications. A paired t-test was used for IOP and medication analysis. Decrease in IOP >25% or IOP 18 mm Hg or less without medication was considered a complete success, with medication - partial success. Failure was considered if the patient needed subsequent filtering surgery. Results were significant with p<0.05. Mean postoperative follow-up was 9.5±2.7 months. RESULTS: Mean preoperative IOP was 25.8±6.2 mm Hg (95% CI 22.7-28.9), mean number of medications - 2.4±0.8 (95% CI 2.2-2.6). At each follow-up a decrease in mean IOP was observed, resulting in 11.9±3.0 mm Hg (95% CI 11.513.1) at 6 months (p=0.000000008) and 12.3±2.5 mm Hg (n=10; 95% CI 11.2-12.6) at 12 months (p=0.00000001). This represents a reduction in IOP from baseline of 51.7±19.0% (95% CI 47.2-56.2) at 6 months and 49.8±15.3% (95% CI 45.0-54.6) at 12 months. Mean number of medications use decreased to 0.6±1.1 (95% CI 0.3-0.9; p=0.0000002) and 0.9±1.3 (95% CI 0.5-1.3; p=0.004) at 6 and 12 months respectively. Complete and partial success were observed in 13 and 5 cases at 6 months and 6 and 4 cases at 12 months (n=10). Intraoperatively, microperforation of trabecular meshwork (TM) in areas other than exposed part of SC occurred in 3 out of 18 cases. Postoperatively, not a single case of inflammation at insertion site, of hypotony, or shallow chamber was observed. Gonioscopically the device was in SC in all, except 2 cases, where one end of the device was lying in anterior chamber without contact with intraocular structures. Some blood was observed in SC at the device site in 3 cases, which cleared spontaneously after 3-4 days. There was 1 case with raised IOP after operation, which required Nd-YAG laser trabeculopuncture and one glaucoma medication. There were no failure cases. CONCLUSION: Six months and one year results of SCE insertion in surgical management of OAG show significant reduction in IOP from the baseline and in hypotensive medications use.