Initial intraocular pressure reduction by mono‐ versus multi‐therapy in patients with open‐angle glaucoma: results from the Glaucoma Intensive Treatment Study

PURPOSE: To study newly diagnosed glaucoma patients given mono- or multi-therapy regarding differences in initial intraocular pressure (IOP) reduction, target IOP levels reached and influence of untreated baseline IOP on IOP reduction. METHODS: Patients newly diagnosed with manifest primary open-angle glaucoma and included in the Glaucoma Intensive Treatment Study (GITS) were randomized to immediate intensive treatment with any of three different IOP-lowering substances supplied in two bottles plus 360° laser trabeculoplasty or to conventional stepwise treatment starting with a single-drug. Intraocular pressure reduction was analysed 1 month after initiation of treatment. RESULTS: One hundred eighteen patients (143 eyes) received mono-therapy and 122 patients (152 eyes) multi-therapy. Median baseline IOP was 24.0 (min: 9.7, max: 56.0) mmHg in mono-therapy eyes and 24.0 (min: 12.3, max: 48.5) mmHg in multi-therapy eyes (p = 0.56). After 1 month in the two groups, respectively, values for median IOP reduction were 6.3 (range: -5.3-31.0) and 11.0 (range: 0.7-34.5) mmHg, and for mean relative decline 26.8 (range: -32.0-55.4) and 46.0 (range: 4.6-81.6) % (p = 0.000). A larger proportion of the multi-therapy patients reached each target IOP level (p = 0.000). The higher the baseline IOP, the larger the observed pressure reduction, considering both absolute and relative figures. The effect was more pronounced in eyes with multi-therapy than in those with mono-therapy (p = 0.000). For every mmHg higher IOP at baseline, the IOP was reduced by an additional 0.56 (mono-therapy) or 0.84 (multi-therapy) mmHg. CONCLUSION: Intensive treatment led to considerably greater IOP reduction than mono-therapy. Among patients with IOP ≥30 mmHg at diagnosis an IOP of <16 was reached in 2/3 of those with multi-therapy but in none with mono-therapy. The IOP reduction was highly dependent on the untreated IOP level.