DSLT in Normal Tension Glaucoma (NTG) Asian Eyes

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