Lens survival after tube shunt surgery: Risk factors impacting time to cataract extraction following glaucoma drainage implant surgery.

Purpose: To determine the lens survival time following glaucoma drainage implant (GDI) surgery and identify the risk factors that may predict the time to cataract surgery.

Design: Retrospective cross-sectional study.

Methods: Phakic patients who underwent GDI surgery at a large tertiary referral center between January 1, 2016 and June 1, 2022 were included. Demographic and clinical data were collected and analyzed using multivariate and survival analyses, with statistical significance set at P < 0.05. The main outcome was time to cataract surgery (called lens survival time). Survival analyses were conducted using Kaplan-Meier and Cox regression methods.

Results: Sixty-eight phakic subjects underwent GDI surgery, with a mean age of 56.4 ± 14.9 years. Of them, 36 subjects (53%) had primary glaucoma and 32 (47%) had secondary glaucoma. GDI 6-month success (intraocular pressure ≤21 mmHg) was achieved in 63 subjects (92%). Forty-three subjects had three or more years of follow-up data available and were included in the survival analysis. Median and mean lens survival time were 16 ± 2 and 20 ± 3 months, respectively. At 1, 2, and 5 years, the proportions of lenses that survived were 60.5% (26 lenses), 27.9% (12 lenses), and 2.3% (one lens), respectively. Timing of subsequent cataract surgery did not correlate significantly with subject demographics or type of glaucoma.

Conclusions: Cataract progression occurred in nearly all patients following GDI surgery. None of the factors studied predicted the timing of cataract surgery, suggesting that cataract formation is primarily influenced by the surgery itself, with minimal impact from patient-specific risk factors.