Intraocular Pressure (IOP) Lowering Effect of Selective Laser Trabeculoplasty Versus Prostaglandin Analogues in Angle Closure Glaucoma

• Status: Unknown status
• Trial end date: 2011-03-01
• Target enrollment: 0
• Participant gender: All

Summary

Glaucoma affects 66 million people worldwide and is the leading cause of irreversible blindness, and Primary angle-closure glaucoma (PACG) is a major form of glaucoma in Asia.

Laser peripheral iridotomy (LPI) has been advocated as the first line treatment in all cases of PACG. In addition to relieving the relative pupil block element of the condition, it can open up the drainage angle, alleviating appositional and synechial angle-closure and in the long-term this may control intraocular pressure (IOP) and prevent progression of glaucomatous optic neuropathy. 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.

Laser trabeculoplasty has been a recognized treatment option for Primary open angle glaucoma (POAG) since the 1980s. Recently a more selective and less destructive method of performing laser trabeculoplasty has evolved. Selective Laser Trabeculoplasty (SLT) specifically targets the pigmented trabecular meshwork cells without producing collateral damage and destruction to adjacent structures. Morphologic study performed on human autopsy eyes treated with SLT noted no structural or collateral thermal damage to the trabecular beams in the uveal and corneoscleral meshwork. As SLT specifically has its effect on the targeted pigmented trabecular meshwork it is unlikely to generate PAS. It may be a useful treatment option for PACG patients in whom the angle has widened following laser peripheral iridotomy.

The proposed study is a randomized controlled trial to assess the effectiveness of SLT in reducing IOP in cases of PACG in which the angle has opened up following LPI, but IOP remains high(>21 mmHg). 100 subjects will be randomized to receive either SLT or medical treatment to achieve IOP control. They will be followed up for 6 months.

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

Details

• Lead Sponsor: Singapore Eye Research Institute
• Treatments: Brimonidine Tartrate; Timolol; Travoprost

Criteria

Inclusion Criteria:

• Diagnosis of primary angle closure or primary angle closure glaucoma with documented pre-LPI angle closure of ≥180 degrees of the angle (Trabecular meshwork not visible in primary position using gonioscopy)

• One month post LPI, angle has opened up (visibility of trabecular meshwork) for at least 180 degrees of the angle

• Intraocular pressure between 21-≤30 mmHg without treatment following LPI OR Intraocular pressure between 21-≤30 mmHg after wash out regimen as described below for patients who are already medications following LPI.

• Informed Consent

• Age more than 21 years

Exclusion Criteria:

• 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 or visual field constriction involving <100 of the central visual field performed with the Humphrey Visual Field Analyzer II using the SITA STD algorithm with a 24-2 test pattern.

• 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.

• Previous intraocular surgery, SLT, ALT, refractive surgery or iridoplasty.

• Documented previous history of angle closure.

• 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.