Long-term outcome of pars plana Ahmed valve implant and vitrectomy in eyes with refractory glaucoma

Background: Pars plana vitrectomy with implantation of an Ahmed glaucoma valve in the vitreous cavity has been reported with a success rate in the management of refractory and neovascular glaucoma. This study aimed to present the outcomes of pars plana Ahmed glaucoma valve (PPAV) surgical implantation in cases with refractory glaucoma. Methods: In this single-center, retrospective, comparative study, 87 consecutive patients diagnosed with refractory glaucoma who underwent PPAV surgical implantation between October 2015 and October 2019 were evaluated. A successful post-op outcome was defined as postoperative intraocular pressure (IOP) less than or equal to 21 mmHg upon examination and a reduction in the number of anti-glaucoma agents used at the latest follow-up. Results: As a final count, 81 eyes of 78 patients with refractory glaucoma were included; 54 (66.66%) of the eyes had neovascular glaucoma. The mean follow-up was 20.65 ± 12.17 months (range: 2?52 months). The mean pre-op IOP was 40.01 ± 1.19 mmHg and reduced significantly to 16.73 ± 0.82 mmHg at the latest follow-up (P < 0.001); thus, a successful IOP outcome was achieved in 88.89% of eyes. The mean number of anti-glaucoma agents decreased significantly from 2.86 ± 0.09 pre-operatively to 1.46 ± 0.11 at the latest follow-up (P < 0.001); while 61 (75.31%) of eyes had a reduction in the number of IOP lowering eye drops, and 14 (17.28%) had no need for IOP lowering eye drops. Conclusions: PPAV surgery is a successful procedure for IOP reduction in patients with refractory glaucoma. Our study demonstrated either elimination or reduction of IOP, lowering eye drops postoperatively. Large scale studies with a comparison group, a longer follow-up, and having various subtypes of glaucoma are required as future research to confirm these outcomes.