Collaborative Initial Glaucoma Treatment Study (CIGTS)

Collaborative Initial Glaucoma Treatment Study (CIGTS)


–       To compare the effectiveness of standard medical therapy versus filtration surgery to treat newly diagnosed open-angle glaucoma


–       Randomized, controlled clinical trial

–       607 patients with newly diagnosed with open angle glaucoma were randomized to a medication treatment regimen or filtration surgery

–       Medication regimen: topical medications starting with a one drug regimen with additional medications added if visual field loss progressed or if intraocular pressure remained elevated. If medications proved ineffective, the patient would undergo argon laser trabeculoplasty prior to trabeculectomy.

–       Patients assigned to immediate filtration surgery would undergo trabeculectomy followed by ALT and medications, if surgery failed

–       Follow up examinations occurred at community ophthalmologists and at Clinical Centers (month 3, 6 and biannual visits afterwards)

–       Eligible patients were age 25 to 75 years old with IOP 20 mm Hg or greater and documented optic nerve damage and/or visual field loss

–       Other causes of glaucoma other than primary open-angle glaucoma, pigmentary glaucoma or pseudoexfoliation glaucoma were excluded.


–       At up to 5 years follow up, both groups had substantial/sustained decrease in IOP

–       Surgical group’s IOPs ran 2-3 points lower than medication group

–       Initially over first three years, surgical group had more VF and more VA loss. Difference disappeared after four/five years

–       Surgery group had more cataract extractions than the medical group.

–       Both groups were satisfied with the quality of life associated with their treatment.

–       Surgery group reported more eye symptoms over the first few years of follow up.

–       Medical group reported inconsistent systemic symptoms


–       No changes to current therapeutic approaches recommended based on initial data for treating OAG

–       Given chronic, progressive nature of glaucoma, longer term follow-up is required to be able to further evaluate and recommend specific treatments