Outcomes of Ahmed glaucoma valve FP8 versus FP7 in adult secondary glaucoma

Aim To compare the outcomes of Ahmed glaucoma valve (AGV) pediatric FP8 versus the large-sized adult FP7 implants in an adult secondary glaucoma. Methods Patients who underwent AGV implantation from January 2011 to December 2016 for adult secondary glaucoma (due to causes other than post-vitreoretinal/buckle surgery glaucoma) with a follow-up of 6 months were included for this retrospective study. Success was defined as IOP > 6 mm Hg and < 21 mm Hg without any loss of vision, with or without the need of anti-glaucoma medications or additional procedures for control of IOP. Hypertensive phase was defined as IOP > 21 mmHg at any visit in the first 6 months of postoperative follow-up period, while failure was defined as IOP > 21 mm Hg even after medications or additional procedures, need of removal of implant or loss of light perception. Cumulative survival rates and intraoperative or postoperative complications along with IOP profiles were compared between the implants. Results Of 43 patients, 19 patients underwent FP7 and 24 patients underwent FP8 Ahmed Glaucoma valve implantation. The IOP significantly reduced in both groups from baseline (31 ± 8.2 mm Hg in FP7 eyes and 37 ± 13.1 mm Hg in FP8 eyes) by a mean of 64 ± 23.5% in FP8 and 64 ± 21.5% in FP7 group, respectively, p = 0.8 with comparable final IOP of 16.5 mm Hg and 16.9 mm Hg, respectively, p = 0.9. Both groups had 75% qualified success rates at 20 months after surgery with similar rates of need for postoperative medications or incidence of hypertensive phase. The FP8 eyes had more frequent conjunctiva-related complications in eyes with prior surgeries and preoperative conjunctival scarring while the other complications were similar in the two groups. Conclusion Surgical outcomes of adult FP7 and pediatric FP8 AGV in adult secondary glaucoma seem to achieve similar IOP control and success rates. This suggests that smaller-sized FP8 can be used in adult glaucoma with good surgical outcomes albeit with careful case selection in eyes with extensive preoperative scarring to avoid conjunctival thinning-related complications postoperatively.