Netarsudil 0.02% Alters Episcleral Venous Flowrates: A Clinical Trial Using Erythrocyte Mediated Angiography

Objective To characterize the effect of netarsudil 0.02% on episcleral blood flow in treatment naïve glaucoma suspect or ocular hypertension subjects. Design Prospective, unmasked, single-arm cohort study. Participants Ten treatment-naïve patients with a diagnosis of glaucoma suspect or ocular hypertension. Methods Erythrocyte mediated angiography (EMA) was used to measure episcleral erythrocyte velocity, vessel diameter, and blood flow at baseline before treatment, 1 hour after drop instillation (T1), 1 to 2 weeks after daily netarsudil 0.02% drop use (T2), and 1 hour after drop instillation at the 1-to-2-week timepoint (T3). Intraocular pressure (IOP) and blood pressure were measured at each visit. Main outcome measures Change in episcleral venous erythrocyte velocity, diameter, and blood flow between timepoints analyzed using generalized estimating equation (GEE) models. Results Of the 18 eligible study eyes of 10 enrolled treatment-naïve subjects, baseline IOP was 16.8±3.6mmHg (mean±SD), which significantly decreased to 13.9±4.2mmHg at T1, 12.6±4.1mmHg at T2, and 11.8±4.7mmHg at T3 (p<0.05 at each timepoint compared to baseline). Episcleral vessels averaged 61.3±5.3μm in diameter at baseline which increased significantly at all post-treatment timepoints (78.0±6.6, 74.0±5.2, 76.9±6.9 μm, respectively; mean±SD, p<0.05 for each timepoint). Episcleral venous flowrates were 0.40±0.22 uL/min (mean±SD) at baseline, which increased significantly to 0.69±0.45 uL/min at T1 (p=0.01), did not significantly differ at T2 (0.38±0.30 uL/min), and increased significantly to 0.54±0.32 uL/min at T3 (p<0.05 compared to baseline and T2). Conclusions Netarsudil causes episcleral venous dilation at all timepoints and resulting increases in episcleral venous flowrates one hour after drop instillation. Increased episcleral venous flow, associated with decreased episcleral venous pressure (EVP), may result in lowered IOP.