Combined pars plana glaucoma drainage device placement and vitrectomy using a vitrectomy sclerotomy site for tube placement: a case series

PurposeThe purpose of this study is to report the safety and efficacy of pars plana glaucoma drainage devices with pars plana vitrectomy using one of the vitrectomy sclerotomy sites for tube placement in patients with refractory glaucoma.MethodsRetrospective case series of 28 eyes of 28 patients who underwent combined pars plana glaucoma drainage device and pars plana vitrectomy between November 2016 and September 2019 at Massachusetts Eye and Ear. Main outcome measures were intraocular pressure (IOP), glaucoma medication burden, best corrected visual acuity, and complications. Statistical tests were performed with R and included Kaplan-Meier analyses, Wilcoxon paired signed-rank tests, and Fisher tests.ResultsMean IOP decreased from 22.8mmHg to 11.8mmHg at 1.5years (p=0.002), and mean medication burden decreased from 4.3 to 2.1 at 1.5years (p=0.004). Both IOP and medication burden were significantly lower at all follow-up time points. The probability of achieving 5 <IOP<less than or equal to>18mmHg with at least 20% IOP reduction from preoperative levels was 86.4% at 1year and 59.8% at 1.5years. At their last visit, three eyes (10.7%) achieved complete success with IOP reduction as above without medications, and 14 eyes (50.0%) achieved qualified success with medications. Hypotony was observed in 1 eye (3.6%) prior to 3months postoperatively and 0 eyes after 3months. Visual acuity was unchanged or improved in 23 eyes (82.1%) at their last follow-up. Two patients had a visual acuity decrease of >2 lines. Two eyes required subsequent pars plana vitrectomies for tube obstruction, and one eye had transient hypotony.ConclusionsThe results of pars plana glaucoma drainage device and pars plana vitrectomy using one of the vitrectomy sclerotomy sites for tube placement are promising, resulting in significant IOP and medication-burden reductions through postoperative year 1.5 without additional risk of postoperative complications. Inserting glaucoma drainage devices into an existing vitrectomy sclerotomy site may potentially save surgical time by obviating the need to create another sclerotomy for tube placement and suture one of the vitrectomy ports.