Effect of Timolol on the Diurnal Intraocular Pressure in Exfoliation and Primary Open-angle Glaucoma

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Abstract
Objective: To describe and compare the diurnal intraocular pressure (IOP) variation in patients with exfoliation glaucoma (EXG) and primary open-angle glaucoma (POAG) who were treated with a solution of timolol maleate (0.5%) twice daily. Design: Consecutive Greek patients who were newly diagnosed as having EXG or POAG were prospectively investigated; they underwent 24-hour diurnal IOP measurements first without therapy and then 6 months afterward while they were being treated with timolol maleate (0.5%). After matching for age, 38 pairs of patients with these 2 types of glaucoma were compared. Results: Untreated patients with EXG had significantly higher IOP values for all time points assessed and a greater mean range of IOPs (11.8 mm Hg for EXG vs 7.6 mm Hg for POAG; P≤.001 ). Following therapy with timolol maleate (0.5%) given twice daily, patients with EXG had higher IOP values for the measurements that were obtained at 6 and 10 am, 10 pm, and 2 am, a higher mean range of IOPs (7.0 mm Hg for EXG vs 5.6 mm Hg for POAG; P=.03), and a higher maximum IOP (mean, 24.9 mm Hg for EXG vs 20.9 mm Hg for POAG; P=.003). The reduction of the range of diurnal variation of IOP was more pronounced in patients with EXG than in patients with POAG (40% vs 26%; P=.04). Twenty-two (58%) of 38 patients with EXG and 20 (53%) of 38 patients with POAG had peak IOP values that were found outside office hours. Only 5 (13%) of the patients with EXG exhibited an IOP of 18 mm Hg or less at all time points compared with 12 (32%) of the patients with POAG (P=.05). Conclusion: Despite a greater initial IOP reduction in the patients with EXG treated with timolol, a higher IOP and significant fluctuation in the diurnal curve of IOP during the time in which patients received therapy still characterized EXG from POAG.