Glaucoma Laser Trial (GLT) Glaucoma Laser Trial Followup Study (GLTFS)

Purpose

To compare the safety and long-term efficacy of argon laser treatment of the trabecular meshwork with standard medical treatment for primary open-angle glaucoma.

Background

During the last decade, argon laser trabeculoplasty (ALT) has often been used instead of surgery as the treatment of choice in cases of open-angle glaucoma that could not be controlled by drugs. ALT treatment consists of tiny laser burns evenly spaced around the trabecular meshwork. It sometimes has been found to be effective in controlling glaucoma, although many eyes still require some medical treatment.

Description

The Glaucoma Laser Trial (GLT), a randomized, controlled clinical trial, was conducted to determine whether ALT is effective in patients with newly diagnosed, primary, open-angle glaucoma. Each of the 271 patients in the trial received argon laser treatment in one eye and standard topical medication in the other eye. The eye to be started on medicine and the eye that would get the laser treatment were randomly selected. The Glaucoma Laser Trial Followup Study was a followup study of 203 of the 271 patients who enrolled in the Glaucoma Laser Trial. By the close of the Glaucoma Laser Trial Followup Study, median duration of followup since diagnosis of primary, open-angle glaucoma was 7 years (maximum, 9 years).

The argon laser treatment was done in two sessions 1 month apart, with one-half of the trabecular meshwork treated with 45 to 55 laser burns in each session. Patients were seen for a followup visit 3 months after the first laser treatment and every 3 months thereafter for a period of at least 2 years. At each visit, examination of the eyes included a check of intraocular pressure and visual acuity. Visual field examinations were performed 3, 6, and 12 months after randomization and annually thereafter. Disc stereo photographs were taken 6 and 12 months after randomization and annually thereafter.

The results of these examinations determined whether treatment should be changed. If the pressure in either eye had not been reduced to the desired level, the physician changed the medication in the eye treated with drops or started the use of drops in the laser-treated eye according to a standardized procedure being used in the trial. If intraocular pressure was still not successfully reduced, surgery or further laser treatment may have been required.

Patient Eligibility

At the time of recruitment, patients had to be at least 35 years old with an intraocular pressure of at least 22 mm Hg or greater in each eye and evidence of optic nerve damage in at least one eye.

Patient Recruitment Status

Completed. Recruitment was conducted between January 1984 and April 1987.

Current Status of Study

Completed.

Results

Over the course of the Glaucoma Laser Trial and Glaucoma Laser Trial Followup Study, the eyes treated initially with argon laser trabeculoplasty had lower intraocular pressure and better visual field and optic disk status than their fellow eyes treated initially with topical medication. As compared with eyes initially treated with medication, eyes initially treated with laser trabeculoplasty had a 1.2 mm Hg greater reduction in intraocular pressure (p < 0.001) and 0.6 db greater improvement in the visual field (p < 0.001) from entry into the glaucoma laser trial. the overall difference between eyes with regard to change in ratio of optic cup area to optic disk area from entry into the glaucoma laser trial was -0.01 (p = 0.005), which indicated slightly more deterioration for eyes initially treated with medication.

Conclusions

Initial treatment with argon laser trabeculoplasty was at least as efficacious as initial treatment with topical medication.

Publications

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial (GLT): 6. Treatment group differences in visual field changes. Am J Ophthalmol 120: 10-22, 1995.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial (GLT) and Glaucoma Laser Trial Followup Study: 7. Results. Am J Ophthalmology 120: 718-731, 1995.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial (GLT): 5. Subgroup differences at enrollment. Ophthalmic Surg 24: 232-241, 1993.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial (GLT): 3. Design and methods. Controlled Clinical Trials 12: 504-524, 1991.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial: 4. Contra-lateral effects of timolol on the intraocular pressure of eyes treated with ALT. Ophthalmic Surg 22: 324-329, 1991.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial (GLT): 2. Results of argon laser trabeculoplasty vs. topical medicines. Ophthalmology 97: 1403-1413, 1990.

Glaucoma Laser Trial Research Group: The Glaucoma Laser Trial: 1. Acute effects of argon laser trabeculoplasty on intraocular pressure. Arch Ophthalmol 107: 1135-1142, 1989.

Resource Centers

Chairman's Office
Hugh Beckman, M.D.
Department of Ophthalmology
Sinai Hospital of Detroit
6767 West Outer Drive
Detroit, MI 48235
Telephone: (313) 493-5157

Coordinating Center
Curtis L. Meinert, Ph.D.
Johns Hopkins University
Center for Clinical Trials
615 North Wolfe Street, Room 5010
Baltimore, MD 21205
Telephone: (410) 955-8175
Fax: (410) 955-0932

NEI Representative

Natalie Kurinij, Ph.D.
National Eye Institute
National Institutes of Health
Executive Plaza South, Suite 350
6120 Executive Boulevard, MSC 7164
Bethesda, MD 20892-7164
Telephone: (301) 496-5983
Fax: (301) 402-0528

Last Updated: 10/23/1999

This page was last modified in October 2008

U. S. Department of Health and Human Services

National Institutes of Health