Asymptomatic Narrow Angles - Laser Iridotomy Study; Multicentric RCT

Singapore National Eye Centre (Other)
Overall Status
Unknown status ID
National Medical Research Council (NMRC), Singapore (Other)

Study Details

Study Description

Brief Summary

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.

Condition or Disease Intervention/Treatment Phase
  • Procedure: Laser Peripheral Iridotomy

Detailed Description

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.

Study Design

Study Type:
Intervention Model:
Parallel Assignment
None (Open Label)
Primary Purpose:
Official Title:
Prophylactic Laser Iridotomy for Eyes With Narrow Drainage Angles; A Randomised Controlled Trial
Study Start Date :
Jan 1, 2005
Study Completion Date :
Jan 1, 2013

Outcome Measures

Primary Outcome Measures

  1. Peripheral anterior synechiae formation []

  2. IOP elevation >21 mm Hg []

  3. Development of acute angle closure event []

Secondary Outcome Measures

  1. Changes in the grading of Modified Schaffer Grading []

  2. Development of glaucomatous optic neuropathy []

  3. Development of corresponding visual field loss by automated perimetry []

  4. Change in HRT optic disc parameters []

  5. Change in UBM angle parameters []

  6. Formation of disc pallor []

Eligibility Criteria


Ages Eligible for Study:
50 Years and Older
Sexes Eligible for Study:
Accepts Healthy Volunteers:
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.

Contacts and Locations


Site City State Country Postal Code
1 Singapore Eye Research Institute Singapore Singapore 168751

Sponsors and Collaborators

  • Singapore National Eye Centre
  • National Medical Research Council (NMRC), Singapore


  • Principal Investigator: Tin - Aung, FRCSEd PhD, Singapoe National Eye Centre

Study Documents (Full-Text)

None provided.

More Information


None provided.
Responsible Party:
, , Identifier:
Other Study ID Numbers:
  • R358/16/2004
First Posted:
Jul 4, 2006
Last Update Posted:
Jul 4, 2006
Last Verified:
Jun 1, 2006

Study Results

No Results Posted as of Jul 4, 2006