The Effect of High-Intensity Focused Ultrasound on Aqueous Humor Dynamics in Patients with Glaucoma

Abstract

To investigate the effects of high-intensity focused ultrasound (HiFU) on aqueous humor dynamics in patients with glaucoma. Comparative, nonrandomized, interventional study. Adult patients with a diagnosis of open-angle glaucoma or ocular hypertension with suboptimal intraocular pressure (IOP) control despite maximum medical treatment who required further IOP optimization. All patients underwent comprehensive ophthalmic examination before aqueous humor dynamics study measurements, including fluorophotometry and digital Schiøtz tonography. All patients received 6 seconds of HiFU therapy. Aqueous humor dynamics studies were repeated 3 months after the treatment (patients had 4-week washout from their glaucoma medication before their aqueous humor dynamics study measurements at baseline and the 3-month visit). Intraocular pressure, facility of topographic outflow, aqueous flow rate, and uveoscleral outflow. Thirty eyes of 30 patients were included in the study. At the 3-month postoperative visit, the mean postwashout IOP was reduced by 16% (31.7±5.3 vs. 26.6±4.8 mmHg, P= 0.004), and aqueous flow rate was decreased by 15% (2.07±0.73 vs. 1.77±0.55 μl/min, P= 0.05) from baseline. Neither the tonographic outflow facility nor the uveoscleral outflow was significantly different from baseline. There is a 20% risk of treatment failure (those who needed further glaucoma surgical intervention) within 1 month after a single HiFU treatment (n= 6). Only 25 patients (80%) were able to undergo post-treatment washout measurements, and in these eyes, only 26.6% of eyes achieved >20% IOP reduction at 3 months compared with baseline. We investigated the aqueous humor dynamics effects of a cyclodestructive procedure and specifically HiFU in patients with uncontrolled open-angle glaucoma on maximum tolerated medical therapy. High-intensity focused ultrasound reduced IOP 3 months postoperatively by 16% and aqueous flow decreased by 15% without any significant effect on tonographic outflow facility and uveoscleral outflow.