THE GLAUCOMA LASER TRIAL (GLT) .6. TREATMENT GROUP-DIFFERENCES IN VISUAL-FIELD CHANGES

PURPOSE: To determine the differences in visual fields during 42 month s (3 1/2 years) of follow up between eyes treated with argon laser tra beculoplasty first and eyes treated with topical medication first in p atients with newly diagnosed primary open-angle glaucoma. METHODS: Vis ual field examinations were obtained at enrollment, three and six mont hs, and at six-month intervals thereafter during follow-up of 271 pati ents enrolled in the Glaucoma Laser Trial, Numeric analyses of the exa mination results, including global indices and patterns of localized c hanges, as well as masked subjective clinical impression, were used to compare the two treatment groups. RESULTS: The mean threshold for eye s treated with laser trabeculoplasty first was 0.3 dB better than that for eyes treated with topical medication first averaged over follow-u p (95% confidence interval, [-0.1, 0.7]; P = .17), More eyes treated w ith 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), Impr ovement was nearly twice as common as deterioration on masked subjecti ve impression in both groups through 30 months (2 1/2 years), Eyes tre ated with laser trabeculoplasty first were judged to have slightly mor e improvement and slightly less deterioration than eyes treated with t opical medication first. CONCLUSION: During follow up, measures of vis ual held status for eyes treated with laser trabeculoplasty first were slightly better than those for eyes treated with topical medication f irst, Statistical significance was attained for only some of the diffe rences, and the clinical implications of such small differences are no t known.