Secondary procedures two years after first-generation trabecular micro-bypass stent placement

Abstract

Purpose : To describe the incidence and outcome of secondary procedures in patients who had cataract surgery with or without implantation of a first-generation trabecular micro-bypass stent (iStent®, Glaukos Corporation, Laguna Hills, CA).

Methods : In this retrospective comparative cohort study, 14 eyes required subsequent laser or intraoperative procedures by 2 years. In the cohort, 134 eyes with open angle glaucoma underwent cataract surgery alone (control group) and 142 eyes simultaneously received first-generation iStent implantation. All surgeries were performed at the Bascom Palmer Eye Institute (BPEI) and the Miami Veterans Affairs Hospital (VA).

Results : Six eyes in the iStent group underwent Nd:YAG capsulotomy compared to 1 eye in the control group. Seven eyes in the iStent group had subsequent glaucoma procedures (glaucoma drainage device) versus 1 eye in the control group (transscleral cyclophotocoagulation (TS-CPC)). One eye in the iStent group required TS-CPC after glaucoma drainage device implantation. The glaucoma reoperation rate was higher at the VA (N=5) compared to BPEI (N=3). The mean time to glaucoma reoperation was similar in both groups (iStent 23.2 months, SD 8.8 vs. control 23.8 months). Mean baseline IOP in iStent eyes requiring additional glaucoma surgery was 20.7mmHg (SD 5.3) on 2.3 glaucoma medications (SD 1.6) compared to 18mmHg (SD 4.3) on 2.1 medications (SD 1.4) in iStent eyes not requiring further intervention. Mean baseline IOP in the control eye that required surgery was 18mmHg on 2 medications compared to 15.8mmHg (SD 4.0) on 1.2 medications (SD 1.3) for control eyes that did not require additional surgery. Mean follow-up after glaucoma reoperation was 7.6 months (SD 4.7) in the iStent group and 6.4 months in the control. The mean IOP in eyes needing additional glaucoma surgery improved to 12.1mmHg (SD 4.3) on 3 glaucoma medications (SD 1.0) in the iStent group and 12.0mmHg on 3 medications in the control eye at the last follow-up appointment.

Conclusions : The YAG capsulotomy and glaucoma reoperation rates were both higher in the iStent group compared to the control. Additional glaucoma surgery was more common at the VA than at BPEI. The iStent eyes that required reoperation for glaucoma had higher baseline IOP, suggesting more advanced glaucomatous disease.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.