Si Chen, Susannah Waxman, Chao Wang, Sarah Atta, Ralitsa Loewen, Nils A. Loewen

• Purpose To characterize the effects of netarsudil on the aqueous humor outflow tract distal to the trabecular meshwork (TM). Wehypothesized that netarsudil increases outflow facility in eyes with and without circumferential ab interno trabeculectomy (AIT)that removes the TM. Methods Sixty-four porcine anterior segment cultures were randomly assigned to groups with (n= 32) and without circumferential AIT (n= 32). Cultures were exposed to 0.1, 1, and 10μM netarsudil (N= 8 eyes per concentration). For each concentration,IOP and vesselPurpose To characterize the effects of netarsudil on the aqueous humor outflow tract distal to the trabecular meshwork (TM). Wehypothesized that netarsudil increases outflow facility in eyes with and without circumferential ab interno trabeculectomy (AIT)that removes the TM. Methods Sixty-four porcine anterior segment cultures were randomly assigned to groups with (n= 32) and without circumferential AIT (n= 32). Cultures were exposed to 0.1, 1, and 10μM netarsudil (N= 8 eyes per concentration). For each concentration,IOP and vessel diameters were compared with their respective pretreatment baselines. Outflow tract vessel diameters wereassessed by spectral-domain optical coherence tomography (SDOCT) and rendered in 4D (XYZ time series). Results Netarsudil at 1μM reduced IOP both in eyes with TM (−0.60 ± 0.24 mmHg,p= 0.01) and in eyes without TM (−1.79 ±0.42 mmHg,p< 0.01). At this concentration, vessels of the distal outflow tract dilated by 72%. However, at 0.1μMnetarsudilelevated IOP in eyes with TM (1.59 ± 0.36 mmHg,p< 0.001) as well as in eyes without TM (0.23 ± 0.32 mmHg,p<0.001). Vessels of the distal outflow tract constricted by 31%. Similarly, netarsudil at a concentration of 10μM elevated IOP both in eyeswith TM (1.91 ± 0.193,p< 0.001) and in eyes without TM (3.65 ± 0.86 mmHg,p< 0.001). At this concentration, outflow tractvessels constricted by 27%. Conclusion In the porcine anterior segment culture, the dose-dependent IOP changes caused by netarsudil matched the diameterchanges of distal outflow tract vessels. Hyper- and hypotensive properties of netarsudil persisted after TM removal…