The goal of this clinical trial is to evaluate the efficacy of direct selective laser trabeculoplasty (DSLT) or laser treatment in Asian patients with normal tension glaucoma. The main question it aims to answer is:

Does the DSLT reduce intraocular pressure (IOP) and medication use in Asian NTG subjects? Participants will attend routine follow-up visits with their eye surgeon and glaucoma testing such as optical coherence tomography (OCT) imaging and visual field test(s) after the laser study treatment.

Inclusion Criteria:

• Asian descent
• NTG diagnosis: glaucomatous optic neuropathy in patients with IOP measurements consistently lower than 21 mmHg
• Mean deviation (MD) of the visual field between 0 to -12dB
• No significant central vision loss within 5 degrees within 5th percentile
• Age ≥20 years
• NTG patients who are medically controlled on 1-3 medications and safe to wash out or IOP is still insufficient from medications and safe to washout
• Shaffer grade II or more on 3 of the 4 quadrants
• Central corneal thickness (CCT) 450-600µm
• All participants are able to provide written informed consent before participation

Exclusion Criteria:

• Angle closure glaucoma or narrow angle status post laser peripheral iridotomy (LPI), or any other open angle glaucoma excluding NTG
• History of SLT within last 2 years
• History intraocular surgery including refractive surgery, except for history of cataract surgery that has been greater than 1 year
• Patients anticipating cataract surgery during the study follow-up period
• Unable to have DSLT procedure due to pre-limbal findings
• Any presence of relevant ocular diseases including retinal disease with no confirmed cure

There is no plan to share individual participant data (IPD) for this study. The sample size is small and sharing de-identified datasets may not adequately protect participant privacy.