This is a multicentric, randomised, controlled study comparing Laser Iridotomy (LI) to no treatment in subjects with asymptomatic narrow angles (ANA).One eye of each subject with ANA will be randomised to undergo LI and the other eye will be left alone and will serve as an internal control. Subjects are proposed to be followed up once a year for 5 years.

Objective: This study will compare LI versus no treatment in subjects with asymptomatic narrow angles, the anatomical trait that predisposes to primary angle closure glaucoma (PACG), in order to assess the effectiveness of prophylactic treatment in the prevention of blindness due to PACG.

Eligibility: 1. Bilateral Narrow angles; 2. Age 50 years and above; 3. Informed consent obtained prior to or at baseline visit.

Trial Design: Subjects with asymptomatic ANA undergoes randomisation after comprehensive ocular exam followed by randomisation to LI in one eye and no treatment in the other eye. Follow up is done for 5 years with yearly examination.

Inclusion Criteria:

1. Bilateral Narrow angles
2. Age 50 years and above
3. Informed consent obtained prior to or at baseline visit

Exclusion Criteria:

1. Presence of PAS
2. IOP > 21 mm Hg
3. Glaucomatous optic neuropathy and/or CDR > 0.7
4. Secondary angle closure such as uveitis, neovascularisation etc.
5. Prior intraocular surgery or penetrating eye injury
6. Corneal disorders such as corneal endothelial dystrophy except mild corneal guttae
7. Evidence of prior acute angle closure event
8. High risk of acute angle closure.
9. Significant cataract and visual acuity less than 20/40
10. Constant use of contact lens for refractive correction
11. Chronic use of topical or systemic steroids
12. Established retinopathies on ocular treatments (e.g. Diabetic)
13. Any other disease which is likely to cause field loss in next 3 years
14. Severe health problems decreasing life expectancy to less than one year.