Safety and effectiveness of Kumar’s Schlemm’s canal expander in management of open-angle glaucoma in cataract patients

PURPOSE: To evaluate safety and effectiveness of Schlemm's canal expander (SCE) in management of open-angle glaucoma (OAG) in cataract patients. METHODS: A total of 9 cases (9 eyes) having visually significant cataract and insufficiently controlled by their current ocular hypotensive medication(s) glaucoma were operated upon. There were 5 cases of pseudoexfoliation syndrome, rigid pupils and weakening of Zinn's ligaments resulting in instability of native lens and requiring implantation of a capsule tension ring (CTR) into the capsular bag to stabilize it. A one-stage combined surgery - phacoemulsification with in-the-bag implantation of a foldable acrylic hydrophilic intraocular lens (IOL) and implantation of SCE in Schlemm's canal (SC) was performed in all cases. A 4-5 mm long SCE made from 0.05mm thick medical grade vanadium stainless steel wire was implanted into the SC lumen by ab externo approach. Primary outcome measure was intraocular pressure (IOP) change, secondary - number of glaucoma medications pre- and postoperatively and complications. A paired t-test was used for IOP and medication analysis. 25% decrease in IOP or IOP of 18 mm Hg or less without medication was considered a complete success, with medication - partial success. The need for subsequent filtering surgery was qualified as failure. Success was evaluated on the basis of Kaplan-Meier cumulative probability at each follow-up visit. Results were considered statistically significant with p<0.05. Minimum postoperative follow-up was 18 months. RESULTS: Out of 9 operated cases a total of 7 cases (7 eyes) were included for analysis. 1 patient who died of natural causes 3 months after the surgery and another case with incomplete follow up were excluded from the study. Mean preoperative IOP was 26.1+4.6 mm Hg (range: 19.0-30.9; 95% CI 22.7-29.5) and mean number of preoperative medications was 2.1+0.4 (range: 2-3; 95% CI 1.9-2.4). At each follow-up a decrease in mean IOP was observed, resulting in 11.3+3.0 mmHg (range: 7.1-15.3; CI 9.1-13.5) at 18 months (p=0.0000015). This represents a reduction of 56.3+11.6% from the baseline IOP. A reduction in glaucoma medications use was observed at each follow up visit and was 0.9+1.2 (range: 0-3; 95% CI 0.0-1.8) at 18 months (p=0.016). Complete and partial success was observed in 4 and 3 cases at the 18-month point, respectively. Microperforation of the trabecular meshwork (TM) in areas other than the exposed part of SC occurred in 1 case. In 5 cases the device could be pushed into SC completely. In 2 cases one end (0.5 to 1.0 mm in length) of the device was left in the exposed part of SC. No specific complications related to the device were noted. A filtration bleb was noticed in 5 cases on day one, 2 cases at 1 week and 1 case at 1 month. At 3 months and afterwards no filtration bleb was noticed in any of the cases. In 1 case laser capsulotomy for secondary cataract was performed to restore vision. Goniosco-pically the device was in the lumen of the SC in all cases except the case with intra-operative microperforation, where one end of the device was lying in the anterior chamber (AC) without any contact with intraocular structures. CONCLUSION: Eighteen months results of the SCE implantation in surgical management of OAG in cataract patients show significant reduction in IOP from the baseline and in hypotensive medication(s) use.

Schlemm's canal surgery, Schlemm's canal expander, stainless steel spiral Schlemm's canal expander, glaucoma surgery, open angle glaucoma, mini invasive glaucoma surgery, combined surgery for cataract and glaucoma, хирургия шлеммова канала, экспандер шлеммова канала, спиральный экспандер шлеммова канала, хирургия глаукомы, открытоугольная глаукома, миниинвазивная хирургия глаукомы, комбинированная хирургия при катаракте и глаукоме

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