Clinical trial NCT00347178: Asymptomatic Narrow Angles - Laser Iridotomy Study; Multicentric RCT
Official title: Prophylactic Laser Iridotomy for Eyes With Narrow Drainage Angles; A Randomised Controlled Trial
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Asymptomatic Narrow Angles
Primary Angle Closure Suspects
Keywords: Asymptomatic Narrow Angles
Primary Angle Closure Suspects
Laser Peripheral Iridotomy
Randomised Controlled Trial
Lead sponsor: Singapore National Eye Centre
Sponsor class: OTHER_GOV
Collaborators: name: National Medical Research Council (NMRC), Singapore
First posted: 2006-07-04
Enrollment: 544
Sex: ALL
Minimum age (years): 50
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: PREVENTION

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.

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.

Eligibility criteria: 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.

Primary outcomes:
measure: Peripheral anterior synechiae formation
measure: IOP elevation >21 mm Hg
measure: Development of acute angle closure event
Secondary outcomes:
measure: Changes in the grading of Modified Schaffer Grading
measure: Development of glaucomatous optic neuropathy
measure: Development of corresponding visual field loss by automated perimetry
measure: Change in HRT optic disc parameters
measure: Change in UBM angle parameters
measure: Formation of disc pallor
Other outcomes:
Locations:
city: Singapore
country: Singapore
facility: Singapore Eye Research Institute
Study officials:
affiliation: Singapoe National Eye Centre
name: Tin - Aung, FRCSEd PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Baskaran M, Kumar RS, Friedman DS, Lu QS, Wong HT, Chew PTK, Lavanya R, Narayanaswamy A, Perera SA, Foster PJ, Aung T. The Singapore Asymptomatic Narrow Angles Laser Iridotomy Study: Five-Year Results of a Randomized Controlled Trial. Ophthalmology. 2022 Feb;129(2):147-158. doi: 10.1016/j.ophtha.2021.08.017. Epub 2021 Aug 26.
citation: Narayanaswamy A, Baskaran M, Tun TA, Htoon HM, Aung T. Effect of Pharmacological Pupil Dilatation on Angle Configuration in Untreated Primary Angle Closure Suspects: A Swept Source Anterior Segment Optical Coherence Tomography Study. J Glaucoma. 2020 Jul;29(7):521-528. doi: 10.1097/IJG.0000000000001506.