Glaucoma, a group of chronic and progressive optic neuropathies, is characterised by the degeneration of Retinal Ganglion Cells (RGCs) and corresponding visual field defects. (1) Among the various types of glaucoma, Primary Open-Angle Glaucoma (POAG) is the most prevalent, particularly in adult populations. (2) It is a leading cause of irreversible blindness globally, affecting more than 70 million people, of whom approximately 10% are estimated to be bilaterally blind. (3) Despite its high prevalence and severity, POAG often remains undiagnosed until the later stages, as it progresses insidiously with minimal or no symptoms in the early phases. (4) The pathophysiology of POAG involves a multifactorial process that ultimately leads to optic nerve damage. While elevated intraocular pressure (IOP) remains the most significant modifiable risk factor, other factors such as impaired ocular blood flow, oxidative stress, excitotoxicity, and genetic susceptibility also play important roles. (5,6) IOP elevation in POAG is most commonly due to increased resistance to aqueous humor outflow through the trabecular meshwork. Over time, this chronic elevation in IOP leads to increase in cup/disc ratio of the optic disc and irreversible loss of peripheral vision. (5) Traditionally, beta-blockers like Timolol Maleate have played a pivotal role in the pharmacological management of POAG. (7) Timolol is a non-selective beta-adrenergic receptor antagonist that reduces IOP by decreasing aqueous humor production from the ciliary body epithelium. (8) Introduced in the late 1970s, Timolol quickly became a cornerstone in glaucoma treatment owing to its relatively low cost, twice-daily dosing regimen, and consistent efficacy in IOP reduction, typically in the range of 20–30%. (9) However, systemic absorption of Timolol can lead to adverse effects such as bradycardia, hypotension, bronchospasm, and worsening of pre-existing pulmonary conditions, limiting its use in certain patient populations. Additionally, its efficacy may diminish over time due to tachyphylaxis or poor adherence to the twice-daily regimen. (8) Netarsudil has a unique and triple mechanism of action. First, it enhances trabecular outflow by inhibiting Rho-kinase, which leads to relaxation of the trabecular meshwork and increased aqueous outflow through the conventional pathway. Second, it reduces aqueous humor production by inhibiting the nor-epinephrine transporter (NET). Third, it decreases episcleral venous pressure, which is another contributor to elevated IOP. This multifaceted approach is particularly useful because it targets areas of IOP regulation that are not addressed by most other conventional medications. (10) Clinical trials and real-world studies have demonstrated that Netarsudil can reduce IOP by approximately 3–5 mmHg, with once-daily dosing. Its efficacy is more pronounced in patients with lower baseline IOP, making it a useful agent in mild to moderate cases, as well as in combination therapy. From a research standpoint, there is still limited head-to-head comparative data between Netarsudil and Timolol, particularly in the Indian population. Most available literature has focused on comparisons of Netarsudil with prostaglandin analogues, or on its use as an adjunctive therapy. Understanding how Netarsudil performs in comparison to a time-tested agent like Timolol, particularly when used as monotherapy, is important for informing treatment decisions and guidelines.

This was a hospital-based, prospective, randomized comparative interventional study conducted in the Department of Ophthalmology, Mahatma Gandhi Medical College and Hospital, Sitapura, Jaipur. The study included newly diagnosed, treatment-naïve patients of Primary Open-Angle Glaucoma attending the ophthalmology outpatient department (OPD). All evaluations and follow-ups were conducted on an OPD basis over a period of 18 months. Sample Size - The sample size was calculated using the formula for two-way repeated measures ANOVA, assuming an effect size of 0.10, correlation among repeated measures of 0.5, with a statistical power of 80% and a significance level of 5%. Based on this, a minimum of 90 patients were required for the study. These patients were randomly allocated into two equal groups of 45 each: • Group I: Received Topical Netarsudil 0.02%, once daily. • Group II: Received Topical Timolol 0.5%, twice daily. After obtaining informed consent and confirming eligibility, patients were randomly allocated into two groups using the Chit and Box Method to ensure unbiased distribution of treatment. This simple randomization technique involved placing an equal number of chits labelled ‘Netarsudil’ and ‘Timolol’ in a closed box. Each patient was asked to draw one chit, and based on the selection, they were assigned to either Group I (Topical Netarsudil 0.02%) or Group II (Topical Timolol 0.5%). This method helped minimize selection bias and ensured comparable group sizes. Duration of Study - The study was conducted over a period of 18 months, including a 6-month follow-up period. Type of Data Collection - The study involved quantitative data collection, conducted prospectively using a pre-designed and structured patient proforma. The data were collected at baseline and at scheduled follow-up visits over a 6-month period. The proforma was designed to capture comprehensive demographic, clinical, and investigational details relevant to the study objectives. Baseline Data Collection At the time of enrolment, the following information was recorded: • Demographic details: Name, age, sex, residence, registration number. • Ocular history: Complaints such as diminution of vision, eye pain, redness, watering, photophobia, colored haloes, itching, or discharge. • Past medical and ocular history: Previous eye diseases or surgeries, trauma, long-term systemic and ocular drug use, contact lens usage, history of similar past episodes. • Systemic history: Presence of chronic systemic illnesses such as hypertension, diabetes mellitus, COPD, or ischemic heart disease. • Family history: Especially of glaucoma or other hereditary ocular/systemic diseases. Clinical Evaluation Parameters Each patient underwent a comprehensive ophthalmic examination, including: • Visual acuity assessment (unaided and best corrected). • Slit-lamp examination of the conjunctiva, cornea, estimation of anterior chamber depth, angle of drainage patency, iris, pupil, and lens. • Applanation tonometry for intraocular pressure (IOP) measurement. • Fundus examination to assess optic disc changes. • Humphrey Visual Field Analysis for visual field changes. On the basis of the above examination, the patients with changes in visual acuity, raised IOP, characteristic optic disc and/or open angle on gonioscopy and visual field changes were diagnosed as POAG. Treatment Allocation and Drug Administration Patients were randomly divided into two groups (45 in each group): • Group I received Topical Netarsudil 0.02%, once daily at night. • Group II received Topical Timolol 0.5%, twice daily (morning and evening). The medications were administered via topical instillation into the conjunctival sac. Patients were educated on proper techniques of self-instillation and adherence was emphasized at each follow-up. Instillation instruction: Instillation instructions were provided to all participants at the time of drug allocation. Patients were advised to wash their hands thoroughly before and after instilling the eye drops. For proper administration, they were instructed to gently pull down the lower eyelid to form a pouch and instil one drop of the prescribed medication into the conjunctival sac without touching the tip of the bottle to the eye or surrounding structures. After instillation, they were advised to close the eye gently and perform punctal occlusion (pressing the inner corner of the eye) for three minutes to reduce systemic absorption and enhance ocular bioavailability. Group I patients were instructed to instil Netarsudil 0.02% once daily at bedtime, while Group II patients were instructed to instil Timolol 0.5% twice daily, in the morning and evening, maintaining a 12-hour interval. Compliance and correct techniques were reinforced at each follow-up visit. Follow-Up and Ongoing Data Collection Patients were followed up at 1 week, 1 month, 3 months, and 6 months post-treatment initiation. At each visit, the following parameters were reassessed and documented: • Visual acuity testing. • Intraocular pressure (IOP) using Applanation Tonometry. • Slit-lamp examination to monitor any anterior segment changes or drug-related side effects. Inclusion Criteria • Newly diagnosed cases of Primary Open-Angle Glaucoma (POAG); • Age between 20 to 65 years; • Patients of either sex; • Patients willing to participate in the study and able to provide written informed consent; • Patients are willing to comply with the follow-up schedule and medication protocol. Exclusion Criteria • Patients with IOP less than 21 mmHg more than 26 mmHg • Patients with other types of glaucoma, such as advanced POAG, angle-closure, secondary, congenital, neovascular glaucoma, pseudoexfoliative glaucoma etc. • Patients already on anti-glaucoma therapy prior to enrollment • Presence of other ocular pathologies (e.g., uveitis, corneal diseases, retinal diseases) that could interfere with accurate IOP measurement • History of ocular surgery or laser procedures affecting IOP • Pregnant and lactating women • Patients with significant systemic diseases such as diabetes mellitus, hypertension, cardiovascular disease, or other conditions that could confound study results or pose a risk with beta-blocker therapy • Patients with known allergies or hypersensitivity to study medications • Patients are unable or unwilling to attend follow-up visits or adhere to the treatment regimen

The observations were compiled in tabulated manner and results were statistically analysed using appropriate statistical methods. Two group comparison was done using ANOVA test, paired ‘t’ test was applied for intra-group comparison while independent‘t’ test was used for intergroup comparison. A ‘p’ value of < 0.05 was considered statistically significant and ‘p’ value of <0.001 was considered highly statistically significant. Here, Group I constitutes patients receiving Topical Netarsudil Group II constitutes patients receiving Topical Timolol. Table 1: Distribution of patients according to age group (n=90) Age (years) Group I (%) Group II (%) 20-30 01 (2.22%) 02 (4.44%) 31-40 02 (4.44%) 02 (4.44%) 41-50 21 (46.67%) 17 (37.78%) 51-60 11 24.45%) 16 (35.56%) 61-65 10 (22.22%) 08 (17.78%) Table 2: Distribution of patients according to gender (n=90) Gender Group I (%) Group II (%) Male 23 (51.11%) 21 (46.67%) Female 22 (48.89%) 24 (53.33%) Table 3: Comparison of mean Intraocular Pressure (IOP) at different time intervals in group I (Topical Netarsudil) (n=90) IOP (mmHg) Mean Standard Deviation (SD) % difference from baseline t value p value Initial (pre-therapy) 22.8 0.98 - - - 1 week post therapy 21.18 4.5 -7.10 3.33 0.001 1 month post therapy 20.3 2.5 -10.96 1.8 0.073 3 months post therapy 19.4 1.6 -14.91 2.55 0.0114 6 months post therapy 18.3 3 -19.74 3.07 0.003 Table 4: Comparison of mean Intraocular Pressure (IOP) at different time intervals in Group II (Topical Timolol) (n=90) IOP (mmHg) Mean Standard Deviation (SD) % difference from baseline t value p value Initial (pre-therapy) 22.9 2.0 - - - 1 week post therapy 21.1 4.8 -7.86 3.28 0.0012 1 month post therapy 20.2 2.0 -11.79 27.98 0.102 3 months post therapy 19.3 2.0 -15.72 34.75 0.003 6 months post therapy 18.0 3.8 -21.40 41.61 0.005 Table 5: Comparison of mean Intraocular Pressure (IOP) at different time intervals between two groups IOP (mmHg) Group I Group II t value p value Mean Std Dev. Mean Std Dev. Initial 22.8 0.98 22.9 2.0 0.42 0.67 1 week post therapy 21.2 4.5 21.1 4.8 0.14 0.88 1 month post therapy 20.2 2.5 20.2 2.0 0 1.0 3 months post therapy 19.4 1.6 19.3 2.0 0.37 0.71 6 months post therapy 18.3 3.0 18.0 3.8 0.59 0.56

Age: In the present study, participants ranged from 20-65 years, with the majority falling within the 40 – 60 years age bracket for both the groups. This finding is consistent with the known epidemiology of POAG. The inclusion of a broad adult age range enhances the generalizability of the study findings to the typical glaucoma patient cohort encountered in clinical settings. Furthermore, as POAG is often asymptomatic in early stages, routine screening in middle-aged adults remains crucial. Our study underscores the importance of early detection and intervention in this high-risk age group to prevent irreversible optic nerve damage and visual field loss. (11) Gender: In the present study, the distribution of male and female participants was nearly equal across both treatment groups, indicating effective randomization and minimizing gender-related selection bias. This balanced representation allows for a comprehensive assessment of treatment efficacy and safety across genders. This balanced representation ensures that the study findings are applicable to a broad patient population, enhancing the generalizability of the results. Reduction of Intraocular Pressure over time in both groups: The management of Intraocular Pressure (IOP) remains a cornerstone in the treatment of POAG. Among the pharmacologic options, topical Netarsudil 0.02% once daily and topical Timolol 0.5% twice daily represent two distinct classes of agents: a Rho-kinase inhibitor and a non-selective beta-adrenergic blocker, respectively. This part of our discussion compares their IOP-lowering efficacy across different time points — starting from baseline through 1 week, 1 month, 3 months, and 6 months of therapy. Over the course of six months, both topical Netarsudil and topical Timolol demonstrated a consistent and statistically significant reduction in IOP from baseline within their respective groups. In Group I (Topical Netarsudil), mean IOP decreased from 22.8 mmHg at baseline to 18.3 mmHg at six months post-therapy, reflecting a total reduction of 19.74% (t value = 3.07; p value = 0.003). Similarly, Group II (Topical Timolol) showed a reduction from 22.9 mmHg at baseline to 18.0 mmHg at six months post-therapy, marking a comparable drop of 21.40% (t value = 41.6; p value = 0.005). These findings confirm that both medications were effective in achieving meaningful IOP control. What is particularly noteworthy in this study is that the IOP reduction trends were nearly identical between the two groups at every follow-up interval. At one week, one month, three months, and six months, the p-values for intergroup comparisons remained well above the threshold for statistical significance (all p > 0.6). This indicates that neither drug demonstrated superior efficacy over the other in reducing IOP. The similar efficacy observed in our study reinforces the growing body of evidence supporting Netarsudil as a viable first-line or adjunctive therapy, particularly for patients who may benefit from a once-daily dosing schedule. While Timolol remains a well-established and widely used beta-blocker, its twice-daily regimen and systemic side effects may pose challenges for compliance in certain populations. Therefore, Netarsudil’s comparable performance, combined with its simpler dosing, could offer a practical advantage in long-term management of glaucoma.

In conclusion, this study highlights that both topical Netarsudil and topical Timolol are effective in the management of Primary Open-Angle Glaucoma, yielding significant reductions in IOP without notable differences in efficacy suggesting that topical Netarsudil is non-inferior to topical Timolol in efficacy and can be thought of as a useful addition to the armamentarium of anti-glaucoma medications. These findings support the notion that clinicians can employ either treatment option based on specific patient profiles, preferences, and tolerability, without concerns of compromising therapeutic outcomes. Future research should explore longer-term effects of these treatments and assess individual patient responses to optimize glaucoma management strategies, potentially incorporating factors such as age, baseline IOP, and co-existing ocular conditions for more personalized approaches. AUTHORS CONTRIBUTION STATEMENT • Proposed the idea and design of the study.1,2,3 • Assessing Clinical and Ophthalmic evaluation.1,2,3,4 • Data analysis.1,4 • Primary Author.1 • Provided revisions to scientific content to manuscript.1,2 • Provided grammatical revisions to manuscript.2,3,4 CONFLICT OF INTEREST All authors hereby declare that they have no financial interests or personal conflicts that may affect the study in this article.

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