Safety and efficacy of paediatric silicone Ahmed glaucoma valve (AGV) in adult eyes with post-VR surgery glaucoma

Purpose To compare the safety and efficacy of the FP8 AGV (paediatric) with the standard FP7 AGV in adult post-vitreoretinal (VR) surgery glaucoma. Methods We included 45 consecutive eyes with post-VR surgery glaucoma implanted with either FP8 (n = 28) or FP7 (n = 17) AGV between 2008 and 2016. The data analysed included visual acuity (VA), intraocular pressure (IOP), complications, interventions, and outcomes. Results Mean age (p = 0.24), mean baseline VA (p = 0.77), preoperative IOP (p = 0.41), number of antiglaucoma medications (p = 0.92), and previous surgeries (p = 0.16) were comparable in the two groups. The number of eyes with previous belt buckle was significantly higher (p < 0.001) in the FP8 group (17/28) compared with the FP7 group (2/17), indicating space constraint and scarred conjunctiva. The median follow-up (25th, 75th percentile) was 14.7 (9.1, 25.3) months in the FP7 and 9.8 (6.4, 34.7) months in the FP8 groups (p = 0.62). Postoperatively, the median VA (p = 0.24), the mean IOP at final follow-up (p = 0.15), and median number of AGM (p = 0.99) were comparable in both the groups. The median percentage drop in IOP (95% confidence interval) with the FP7 implant was 55% (43.70%) and with FP8 implant was 53.8% (25, 73), (p = 0.20). None in the FP7 group failed, while three eyes in the FP8 group failed. During the study period, two eyes in the FP8 group had tube exposure that was surgically managed. None of the eyes had implant exposure or loss of light perception. Conclusion Use of the paediatric FP8 AGV in adult post-VR surgery glaucoma eyes with severe conjunctival scarring and limited subconjunctival space resulted in reasonable IOP control compared with the standard FP7 AGV implant. There were no eyes with implant extrusion.