Anterior Chamber Washout During Ahmed Valve Glaucoma Surgery Reduces the Incidence of Hypertensive Phase

Abstract

Précis: Intraoperative anterior chamber (AC) washout reduces the odds of hypertensive phase (HP) by 95% compared with those not receiving washout during Ahmed glaucoma implant (AGI), suggesting AC washout is an effective prophylaxis for postoperative HP. Purpose: To characterize the incidence of postoperative HP in patients receiving AC washout at the time of AGI. Patients and Methods: A total of 24 patients with medically refractory glaucoma who underwent AGI surgery at a tertiary academic medical center in Southern California from December 2018 through March 2021 were included in this retrospective comparative case series. Patients who received a pediatric implant and underwent concurrent intraocular surgery or did not complete a minimum of 6 months of follow-up were excluded. Nine patient’s eyes received AC washout and 15 controls that were analyzed through 6 months postprocedure. HP was defined as intraocular pressure (IOP) above 21 mm Hg within 6 months postprocedure with maximum tolerated medical therapy. AC washout was performed by irrigating the AC with a 5 mL balanced salt solution before placing the tube of the AGI into the AC. The rate of postoperative HP, defined as peak IOP >21 mm Hg, at 6 months follow-up, was observed as the primary outcome measure. Results: Patients included in the study had a high mean preoperative IOP (X̅ = 44.11, SD = 13.85). There were no baseline differences between the washout and control groups. The odds of HP were significantly reduced (odds ratio: 0.050; 95% CI: 0.004, 0.706; P = 0.027) for patients who underwent intraoperative AC washout compared with those who did not. Bivariate analysis of subject baseline characteristics revealed that only washout status was significantly different in subjects with HP compared with subjects without HP (P = 0.015). A multivariate logistic regression model using washout status and autoimmune conditions as covariates was significant in predicting HP (X 2 (2) = 12.337, P = 0.002), with washout as a significant predictor when controlling for autoimmune comorbidities (P = 0.027). Conclusions: AC washout significantly decreases the odds of HP after AGI surgery. AC washout with balanced salt solution adds minimal time and risks to surgery and therefore may be an effective adjunct during AGI placement.