The Ahmed glaucoma valve in neovascular glaucoma (An AOS Thesis)

Abstract

Purpose: To evaluate the results of Ahmed glaucoma valve surgery in neovascular glaucoma and control patients.

Methods: In this retrospective comparative study, we reviewed 76 eyes of 76 patients, comparing the surgical outcomes in control patients (N=38) to matched neovascular glaucoma patients (N=38). Success was defined as intraocular pressure (IOP) > or =6 mm Hg and < or =21 mm Hg, without further glaucoma surgery, and without loss of light perception.

Results: Average follow-up for control and neovascular glaucoma patients was 18.4 and 17.4 months, respectively (P = .550). At last follow-up, mean IOP was 16.2 +/- 5.2 mm Hg and 15.5 +/- 12.5 mm Hg (P = .115) in control and neovascular glaucoma patients, respectively. Life-table analysis showed a significantly lower success for neovascular glaucoma patients compared with controls (P = .0096), with success at 1 year of 89.2% and 73.1%, at 2 years of 81.8% and 61.9%, and at 5 years of 81.8% and 20.6% for control and neovascular glaucoma eyes, respectively. Cox proportional hazards regression analysis showed neovascular glaucoma as a risk factor for surgical failure (odds ratio, 5.384, 95% CI, 1.22-23.84, P = .027). Although IOP control and complications were comparable between the two groups, visual outcomes were worse in neovascular glaucoma patients, with 9 eyes (23.7%) with neovascular glaucoma compared with no controls losing light perception vision (P = .002). The majority with loss of vision (5 of 9) had successful control of IOP during the postoperative period.

Conclusion: Neovascular glaucoma patients have greater risk of surgical failure after Ahmed glaucoma valve surgery compared with controls. Despite improved mean IOP with drainage implants, visual outcomes may be poor, possibly due to progression of underlying disease.

FIGURE 1

Comparison of preoperative and postoperative intraocular pressure (IOP) in controls and eyes with neovascular glaucoma. The postoperative IOP was the mean IOP at the last follow-up examination (mean follow-up period was 18.4 ± 14.0 months in controls and 17.4 ± 15.1 months in eyes with neovascular glaucoma). After Ahmed glaucoma valve surgery, the IOP was significantly lowered compared with the preoperative level (P < .001) for both control and neovascular glaucoma eyes. Asterisks indicate significant difference (P < .05) between the preoperative and postoperative IOP.

FIGURE 2

Mean intraocular pressure (IOP) after Ahmed glaucoma valve surgery in controls and eyes with neovascular glaucoma. The mean preoperative IOP of 39.1 ± 11.2 mm Hg and 43.8 ± 11.0 mm Hg (P = .065) was decreased to 17.9 ± 8.4 mm Hg and 16.5 ± 15.8 mm Hg at 1 year (P = .150), and 17.2 ± 4.1 mm Hg and 4.3 ± 5.1 mm Hg at 3 years (P = .028) in controls and eyes with neovascular glaucoma, respectively. Asterisks indicate significant differences (P < .05) between control and neovascular glaucoma eyes at individual time points. M, months; Pre, prior to surgery; W, week; Y, year(s).

FIGURE 3

Average number of glaucoma medications after Ahmed glaucoma valve surgery in controls and eyes with neovascular glaucoma. The mean preoperative number of medications of 4.0 ± 0.9 and 3.3 ± 1.3 (P = .013) was decreased to 1.7 ± 1.6 and 1.0 ± 1.3 at 1 year (P = .166), and 2.0 ± 1.7 and 0.7 ± 1.2 at 3 years (P = .221) in controls and eyes with neovascular glaucoma, respectively. Asterisks indicate P < .05 (preoperatively and 3 months). M, months; Pre, prior to surgery; W, week; Y, year(s).

FIGURE 4

Cumulative probability of success after Ahmed glaucoma valve surgery in controls and eyes with neovascular glaucoma. The percent success for control and neovascular glaucoma eyes was 89.2% and 73.1% at 1 year, and 81.8% and 20.6% at 3 years, respectively. The difference of the survival curves between two groups was statistically significant by log-rank test (P = .0096). N_C, number of control eyes at time point; N_NVG, number of eyes with neovascular glaucoma at time point. Failures (5 control eyes, 14 neovascular glaucoma eyes) were carried forward in life-table analysis.