Argon Laser Peripheral Iridoplasty for Primary Angle Closure Glaucoma

• Status: Unknown status
• Trial end date: 1969-12-31
• Target enrollment: 0
• Participant gender: All

Summary

Glaucoma is the leading cause of irreversible blindness worldwide. With ageing of the population, glaucoma morbidity will rise, causing increased health care costs and economic burden for a condition in which visual loss, once established, cannot be reversed. In contrast to western countries, primary angle closure glaucoma (PACG) is a major form of glaucoma in Asia. In a recent population based survey in Singapore, the prevalence of glaucoma was 3.2% in the Chinese population over 40. Glaucoma was the leading cause of blindness, with PACG the most visually destructive form of the disease.

Laser iridotomy is the current first line treatment for PACG. It acts by relieving pupil block, which in turn may reduce intraocular pressure (IOP) and prevent progression of glaucoma. However recent data indicate that iridotomy is not successful in controlling IOP in the long term, and the majority of cases develop a clinically significant rise in IOP requiring medical therapy or surgery.

Argon laser peripheral iridoplasty (ALPI) offers a new therapeutic option for PACG. The procedure consists of placing contraction burns in the iris periphery which results in contraction of the iris stroma and opening of the angle.

The proposed study is a 2-centre randomized controlled trial to determine whether ALPI is an effective and safe treatment in the management of PACG. 210 patients with PACG and high IOP (>21 mmHg) following laser iridotomy will be randomized to receive ALPI or medical treatment to achieve IOP control. Subjects will be followed up for 12 months and the outcome criteria will be the rate of medical treatment and surgery in each group, and the angle width and configuration.

This will be the first RCT worldwide to address the role of ALPI in PACG. The study findings will have great relevance for the prevention of glaucoma blindness in the elderly.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Singapore National Eye Centre
• Collaborator: National University Hospital, Singapore
• Treatments: Timolol; Travoprost

Criteria

Inclusion Criteria:

• Persistent narrow angle in the presence of a patent laser peripheral iridotomy. A narrow angle is defined as an angle width of 0-10º in 2 or more quadrants of either eye or where the pigmented trabecular meshwork is not visible in for 2 or more quadrants on gonioscopic examination

• Intraocular pressure > 21mmHg on or off topical medication at least four weeks following laser iridotomy

• Intra ocular pressure > 21 mm Hg after wash out regimen as described below for patients who are already on one medication and Iridotomy has been done at least 4 weeks ago.

• Informed Consent

• Age more than 21 years

Exclusion Criteria:

• Age less than 21 years

• Secondary causes of angle closure like subluxed lens, uveitis, trauma and neovascular glaucoma

• Presence of advanced sight-threatening glaucoma defined as vertical cup-disc ratio > 0.9

• Presence of significant synechial angle closure with > 6 clock hours of peripheral anterior synechiae (defined as abnormal adhesions of the iris to the angle that are at least half a clock hour in width and be at least to the anterior trabecular meshwork or higher on indentation gonioscopy)

• Cataract that is deemed significant enough to require surgery during the course of the trial or that makes field testing or optic disc imaging not technically possible- visual acuity less than 20/40 due to any type of cataract.

• Corneal endothelial cell count less than 1000 cells/mm2

• Corneal abnormalities or infection

• Previous intraocular surgery

• Use of contact lens

• Chronic use of topical or systemic steroids

• Participation in another therapeutic drug study within the last 30 days

• Severe health problems precluding follow-up such as end-stage heart disease, kidney disease, respiratory disease, or cancer and life expectancy less than one year.