PURPOSE: To determine the differences in visual fields during 42 months (3 1/2 years) of follow up between eyes treated with argon laser trabeculoplasty first and eyes treated with topical medication first in patients with newly diagnosed primary open-angle glaucoma.METHODS: Visual field examinations were obtained at enrollment, three and six months, and at six-month intervals thereafter during follow-up of 271 patients enrolled in the Glaucoma Laser Trial, Numeric analyses of the examination results, including global indices and patterns of localized changes, as well as masked subjective clinical impression, were used to compare the two treatment groups.RESULTS: The mean threshold for eyes treated with laser trabeculoplasty first was 0.3 dB better than that for eyes treated with topical medication first averaged over follow-up (95% confidence interval, [-0.1, 0.7]; P = .17), More eyes treated with topical medication first (82 [31%] of 261 eyes) than eyes treated with laser trabeculoplasty first (61 [23%] of 261 eyes) had confirmed localized deterioration at least once during follow-up (P = .02), Improvement was nearly twice as common as deterioration on masked subjective impression in both groups through 30 months (2 1/2 years), Eyes treated with laser trabeculoplasty first were judged to have slightly more improvement and slightly less deterioration than eyes treated with topical medication first.CONCLUSION: During follow up, measures of visual field status for eyes treated with laser trabeculoplasty first were slightly better than those for eyes treated with topical medication first, Statistical significance was attained for only some of the differences, and the clinical implications of such small differences are not known.

PURPOSE: To determine differences between the two treatment groups of the Glaucoma Laser Trial with respect to intraocular pressure, visual fields, optic disk cupping, and therapy for primary open-angle glaucoma.METHODS: The Glaucoma Laser Trial was a multicenter, randomized clinical trial designed to assess the efficacy and safety of starting treatment for primary open-angle glaucoma with argon laser trabeculoplasty vs starting with topical medication. The Glaucoma Laser Trial Follow-up Study was a follow up study of 203 of the 271 patients who enrolled in the Glaucoma Laser Trial. By the dose of the Glaucoma Laser Trial Follow-up Study, median duration of follow-up since diagnosis of primary open-angle glaucoma was seven years (maximum, nine years).RESULTS: Over the course of the Glaucoma Laser Trial and Glaucoma Laser Trial Follow-up 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 to eyes initially treated with medication, eyes initially treated with laser trabeculoplasty had 1.2 mm Hg greater reduction in intraocular pressure (P < .001) and 0.6 dB greater improvement in the visual field (P < .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 = .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.

Data collected at enrollment on the 271 patients (542 eyes) who participated in the Glaucoma Laser Trial (GLT) were analyzed for subgroup differences. The subgrouping variables included four patient characteristics (race, sex, age, and history of a vascular disease) and one ocular characteristic (myopia). The strongest differences observed were between blacks and whites. As compared with the eyes of the white patients, those of the black patients had lower mean decibels per test location in the visual field (P < .001), greater mean defect (P < .001), number of abnormal test locations (P < .001), and corrected loss variance (P = .009), as well as greater cup depth (P < .001), and larger mean horizontal (P = .002) and vertical (P < .001) cup/disc ratios.