Long-term clinical outcomes of Ahmed valve implantation in patients with refractory glaucoma

Abstract

Purpose: To evaluate the long-term efficacy of intraocular pressure (IOP) reduction and complications of Ahmed Glaucoma Valve (AGV) implantation in patients with refractory glaucoma.

Design: Retrospective study.

Subjects: The study involved 302 refractory glaucoma patients who underwent AGV implantation and had a minimum follow-up of 6 months between March 1995 and December 2013.

Methods: An operation was defined as successful when (1) the postoperative IOP remained between 5 and 21 mmHg and was reduced 30% compared to the baseline IOP with or without medication, (2) there was no loss of light perception or vision-threatening severe complications, and (3) no additional filtering or aqueous drainage surgery was required. Clinical records were reviewed.

Main outcome measures: IOP, anti-glaucoma medications, and complications.

Results: The mean follow-up period was 62.25 months (range, 6 to 190 months). The cumulative probability of success was 89% at 6 months, 81% at 1 year, 66% at 3 years, 44% at 10 years, and 26% at 15 years. IOP was reduced from a mean of 32.2 ± 10.5 mmHg to 18.6 ± 9.1 mmHg at 1 month, 15.2 ± 7.0 mmHg at 6 months, and 14.2 ± 3.5 mmHg at 15 years. Surgical failures were significantly increased when preoperative IOP was high, and when severe complications occurred after AGV implantation (P < 0.05).

Conclusion: AGV implantation was successful for IOP control in patients with refractive glaucoma in the long term. However, the success rate of surgery decreased over time. Preoperative high IOP and severe complications related to the operation were significant risk factors for failure.

Fig 1. Mean intraocular pressure(IOP) before surgery and during follow-up.

The intervening mean postoperative IOPs were significantly reduced compared to baseline during entire postoperative periods. Error bars indicate 1 standard deviation.

Fig 2. Mean number of medications before surgery and during follow-up.

The mean number of postoperative glaucoma medications ranged from 0.6 to 1.7 during the entire postoperative period. Error bars indicate 1 standard deviation.

Fig 3. Kaplan-Meier estimates of the cumulative probability of valve success for AGV implantation.

The success rate for patients with refractory glaucoma who had undergone AGV implantation was decreased with time. Percent of success cases and number of eyes during the follow-up period are shown in the box.

Fig 4. Kaplan-Meier cumulative probability curve of success in patients with primary and secondary surgery.

The success rates after surgery were not significantly different between primary AGV implantation and secondary AGV implantation. P* value was calculated using log rank analysis.