Comparison of the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure.

PURPOSE

To compare the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure (IOP) in patients with ocular hypertension or early glaucomatous changes.

DESIGN

Prospective, open-label, experimental study with crossover design.

METHODS

Eighteen patients with ocular hypertension or early glaucomatous changes (aged 41 to 79 years) each received topical treatments with timolol (0.5% Timoptic-XE), latanoprost (0.005% Xalatan), and no IOP-lowering medication, for at least 4 weeks. Timolol was given once in the morning upon awakening and latanoprost once in the evening at bedtime. At the end of each treatment period, the patient was housed in a sleep laboratory for 24 hours and IOP was measured every 2 hours using a pneumatonometer. Measurements were taken sitting and supine during the 16-hour diurnal/wake period and only supine during the 8-hour nocturnal/sleep period. Mean diurnal and nocturnal IOP levels were compared among the treatments with timolol, latanoprost, and no medication.

RESULTS

In the diurnal period, the mean IOP under the timolol or the latanoprost treatment was significantly less than the mean IOP under no medication in both the sitting and the supine positions. There was no statistical difference between the timolol and latanoprost treatments. In the nocturnal period, supine IOP with timolol treatment was not different from the supine IOP with no medication but was significantly higher than supine IOP with the latanoprost treatment.

CONCLUSION

Although both once-daily timolol and latanoprost were effective in lowering IOP during the diurnal period, only latanoprost reduced IOP during the nocturnal period.