High-intensity focused ultrasound lowers IOP, aqueous humour flow rate

High-intensity focused ultrasound (HIFU) seems to control intraocular pressure (IOP) by reducing the aqueous humour flow rate, a recent study has found.

The researchers conducted a prospective observational analysis of 16 patients (mean age 63.1±11 years, nine women) with open-angle glaucoma or ocular hypertension who needed further IOP suppression. The primary outcomes were IOP, facility of tonographic outflow, aqueous flow rate, and uveoscleral outflow measured at 1 week, 1 month, 3 months, and 12 months after the HIFU procedure.

Mean IOP at baseline was 28.3±5.7 mm Hg, which dropped to 22.4±8.4 mm Hg by the 12-month follow-up, representing a significant 21-percent decline (p=0.04). Over the same time span, aqueous humour flow rate decreased by 16 percent, from 2.40±0.6 µL/min at baseline to 2.02±0.6 µL/min at 12 months (p=0.0493).

In contrast, no significant 1-year changes were reported for tonographic outflow facility (0.12±0.09 to 0.08±0.05 µL/min/mm Hg; p=0.4) or uveoscleral outflow (0.6±1.3 to 1.3±0.85 µl/min; p=0.2).

Notably, neither IOP (23.4±7.4 to 22.2±7.4 mm Hg; p=0.5) nor aqueous flow rate (1.9±0.7 to 1.4±0.4 µL/min; p=0.2) were significantly altered in the control eyes; tonographic outflow facility and uveoscleral outflow remained unchanged. There were also no treatment-related complications documented.

“In this study, we assessed the change in aqueous humour dynamics at 12 months after the initial HIFU treatment,” the researchers said. “We demonstrated that the effect of a single HIFU application can last up to 12 months.”