This site became the new on June 19th. Learn more.
Show more Menu IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu IMPORTANT: Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu
Give us feedback

Asymptomatic Narrow Angles - Laser Iridotomy Study; Multicentric RCT

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified June 2006 by Singapore National Eye Centre.
Recruitment status was:  Recruiting
National Medical Research Council (NMRC), Singapore
Information provided by:
Singapore National Eye Centre Identifier:
First received: June 30, 2006
Last updated: NA
Last verified: June 2006
History: No changes posted
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 Intervention
Asymptomatic Narrow Angles Primary Angle Closure Suspects Procedure: Laser Peripheral Iridotomy

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Prevention
Official Title: Prophylactic Laser Iridotomy for Eyes With Narrow Drainage Angles; A Randomised Controlled Trial

Further study details as provided by Singapore National Eye Centre:

Primary Outcome Measures:
  • Peripheral anterior synechiae formation
  • IOP elevation >21 mm Hg
  • Development of acute angle closure event

Secondary Outcome Measures:
  • Changes in the grading of Modified Schaffer Grading
  • Development of glaucomatous optic neuropathy
  • Development of corresponding visual field loss by automated perimetry
  • Change in HRT optic disc parameters
  • Change in UBM angle parameters
  • Formation of disc pallor

Estimated Enrollment: 544
Study Start Date: January 2005
Estimated Study Completion Date: January 2013
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.


Ages Eligible for Study:   50 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

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
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00347178

Contact: Tin - Aung, FRCSEd PhD +65 63224581

Singapore Eye Research Institute Recruiting
Singapore, Singapore, 168751
Principal Investigator: Tin Aung, FRCSEd, PhD         
Sub-Investigator: Steve KL Seah, FRCS (Ed)         
Sub-Investigator: Paul TK Chew, FRCS (Ed)         
Sub-Investigator: Hon T Wong, FRCS (Ed)         
Sub-Investigator: Aliza - Jap, FRCOph (Lon)         
Sub-Investigator: Kah G AuEong, FRCS (Ed)         
Sponsors and Collaborators
Singapore National Eye Centre
National Medical Research Council (NMRC), Singapore
Principal Investigator: Tin - Aung, FRCSEd PhD Singapoe National Eye Centre
  More Information Identifier: NCT00347178     History of Changes
Other Study ID Numbers: R358/16/2004
Study First Received: June 30, 2006
Last Updated: June 30, 2006

Keywords provided by Singapore National Eye Centre:
Asymptomatic Narrow Angles
Primary Angle Closure Suspects
Laser Peripheral Iridotomy
Randomised Controlled Trial processed this record on August 23, 2017