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

PURPOSE: To characterize the incidence of postoperative hypertensive phase (HP) in patients receiving anterior chamber (AC) washout at the time of Ahmed glaucoma implant (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, underwent concurrent intraocular surgery, or did not complete a minimum of 6 months follow-up were excluded. 9 patient eyes receiving AC washout and 15 controls that were analyzed through 6 months post-procedure. HP was defined as intraocular pressure (IOP) above 21mmHg within 6 months post-procedure with maximum tolerated medical therapy. AC washout was performed by irrigating the AC with 5 mL balanced salt solution (BSS) before placing the tube of the AGI into the anterior chamber. The rate of postoperative HP, defined as peak IOP >21 mmHg, 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 washout and control groups. The odds of HP were significantly reduced (OR=0.050; 95% CI=[0.004, 0.706]; P=0.027) for patients who underwent intraoperative AC washout compared to those who did not. Bivariate analysis of subject baseline characteristics revealed that only washout status was significantly different in subjects with HP compared to subjects without HP (P=0.015). A multivariate logistic regression model using washout status and autoimmune conditions as covariates was significant in predicting HP (X2(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 BSS adds minimal time and risks to surgery and therefore may be an effective adjunct during AGI placement.