Surgical outcomes of Ahmed valve implantation with mitomycin C in glaucoma with and without high myopia.

BACKGROUND

This study aimed to assess the surgical outcomes of Ahmed glaucoma valve (AGV) implantation in high myopic eyes (axial length [AL] of ≥ 26.0 mm) and to determine whether high myopia independently poses a risk of surgical failure.

METHODS

We retrospectively reviewed 68 eyes from 59 patients with refractory glaucoma who underwent AGV implantation. Eyes were categorised into high myopia (23 eyes, 33.8%) and control (45 eyes, 66.2%) groups. The primary outcome was the surgical success rate, defined as postoperative intraocular pressure (IOP) of 6-21 mmHg or a ≥ 20% reduction from baseline. Surgical success was further classified into criterion A (postoperative IOP ≤ 21 mmHg) and criterion B (postoperative IOP ≤ 15 mmHg). Surgical success rates were estimated using Kaplan-Meier analysis, and risk factors for surgical failure were identified via Cox proportional hazards modelling.

RESULTS

At 1 and 2 years, surgical success was significantly higher in the control group according to criterion A (p = 0.013 and 0.043, respectively). Based on criterion B, the control group also showed better surgical success, although the difference did not reach statistical significance. (p = 0.051). Postoperative IOP was lower in the control eyes throughout all postoperative periods, and the difference reached statistical significance at 6 months (p = 0.017). An AL ≥ 26 mm was a significant risk factor for surgical failure under both criterion A (hazard ratio [HR] = 8.30, p = 0.026) and criterion B (HR = 6.26, p = 0.009).

CONCLUSIONS

AGV implantation in glaucoma eyes with high myopia showed lower surgical success compared to those without high myopia. Longer AL is a significant risk factor for surgical failure, underscoring the importance of careful monitoring after AGV implantation in such cases.