The purpose of this study is to evaluate the effect of microdrops vs. standard eyedrops of 0.5% timolol maleate in adults with primary open-angle glaucoma or ocular hypertension in terms of intraocular pressure-lowering efficacy and cardiovascular side effects.

This randomized, single-masked, parallel study aims to evaluate the safety and efficacy of microdrops of 0.5% timolol maleate administered with Nanodropper (experimental intervention) compared to standard drops of 0.5% timolol maleate (active comparator) in patients with primary open-angle glaucoma (OAG) or ocular hypertension (OHT) at Aravind Eye Hospital. At the beginning of the test day, baseline (pre-drug) intraocular pressure (IOP), resting heart rate (HR), and resting systolic and diastolic blood pressure (BP) measurements will be collected. Participants will be randomized to receive standard eyedrops or microdrops of 0.5% timolol maleate (one drop per eye), which will be administered by a trained technician at t = 0. IOP, HR, and BP measurements will be repeated by a masked investigator at t = 1, 2, 5, and 8 hours after drug administration.

Inclusion Criteria:

• ≥18 years old
• Recent diagnosis of primary OAG or OHT
• Treatment-naive (not currently using ophthalmic medication)
• Baseline IOP between 21-35 mm Hg
• Corrected Snellen visual acuity of 6/60 or better in each eye

Exclusion Criteria:

• <18 years old
• A recent history (within the past 6 months) of ocular trauma, infection, or uveitis
• Baseline IOP <21 mm Hg or >35 mm Hg
• History of cardiovascular, pulmonary, cerebrovascular, or chronic renal disease
• History of borderline or uncontrolled systemic arterial hypertension
• Use of any systemic α-agonist or β-blocker within 30 days of study commencement
• History of receiving general anesthesia within the previous 30 days
• Pregnant women and nursing mothers