This study evaluates the effects of netarsudil (Rhopressa) on the trabecular meshwork in subjects with ocular hypertension or open-angle glaucoma. Participants will be randomized to receive either netarsudil or placebo (artificial tears). High-resolution imaging using adaptive optics gonioscopy, anterior segment optical coherence tomography (AS-OCT), and OCT gonioscopy will be performed at baseline and after approximately 14 days of treatment. The primary objective is to assess changes in trabecular meshwork lamellae spacing, with secondary measures including trabecular meshwork height, width, and Schlemm's canal diameter.

Glaucoma is a leading cause of irreversible blindness and is characterized by progressive optic neuropathy. A major modifiable risk factor is elevated intraocular pressure, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Netarsudil (Rhopressa), a Rho kinase inhibitor, lowers intraocular pressure in part by increasing trabecular outflow and has been shown in preclinical studies to induce structural changes in trabecular meshwork cells and tissues. However, in vivo human data evaluating these effects remain limited.

This prospective, randomized, single-masked study will enroll approximately 50 subjects with ocular hypertension or open-angle glaucoma. Participants will be randomized in a 2:1 ratio to receive either netarsudil ophthalmic solution or placebo (artificial tears). Subjects may undergo a washout period if currently treated with glaucoma medications.

Imaging will be performed using adaptive optics gonioscopy to visualize trabecular meshwork microstructure, as well as anterior segment optical coherence tomography (AS-OCT) and OCT gonioscopy to assess clinically relevant anatomical parameters. Imaging will occur at baseline and after approximately 14-21 days of treatment.

The primary outcome is the change in trabecular meshwork lamellae spacing. Secondary outcomes include changes in trabecular meshwork height and width. Exploratory outcomes include Schlemm's canal diameter and trabecular meshwork endothelial cell counts. These measurements aim to provide in vivo evidence of the structural effects of netarsudil on the aqueous outflow pathway and improve understanding of its mechanism of action in humans.

Inclusion Criteria:

• Adults aged 18 years or older
• Diagnosis of ocular hypertension or open-angle glaucoma
• Eye examination within the past year
• For glaucoma subjects: structural (optic nerve and/or retinal nerve fiber layer) and functional (visual field) findings consistent with glaucoma
• Best-corrected visual acuity of 20/100 or better
• Open anterior chamber angle as confirmed by gonioscopy and anterior segment optical coherence tomography (AS-OCT)
• Intraocular pressure between 18 and 34 mmHg (treatment-naïve or after washout, if applicable)

Exclusion Criteria:

• Known intolerance to netarsudil ophthalmic solution
• Corneal scarring or active corneal disease that would interfere with imaging
• Inability to tolerate gonioscopy procedures
• Females of childbearing potential who are not using effective contraception or are not sterile
• Any condition that, in the opinion of the investigator, would place the subject at increased risk or interfere with study completion