摘要：Objective: The Low- Pressure Glaucoma Treatment study (LoGTs) seeks to evaluate visual field.s.ability in low- pre- ssure glaucoma patients randomized to intraocular pressure reduction in both eyes with topical twice daily brimonidine tartrate 0.2% versus twice daily timolol maleate 0.5% . This article d.s.ribes the LoGTs d.s.gn and presents baseline characteristics of the subjects. d.s.gn: Randomized, multicenter, double- masked clinical trial. Participants: Low- pressure glaucoma patients 30 years of age or older were identified. Exclusion criteria included an untreated pressure of more than 21 mmHg, advanced visual field loss, and contraindications to study medications. Interventions: Randomization of both eyes to double- masked monotherapy with brimonidine or timolol. Follow- up visits included Humphrey 24- 2 full- threshold perimetry, tonometry every 4 months, and annual optic d.s. photography. Main Outcome Measure: Progression of visual field loss. Results: One hundred ninety patients were randomized between 1998 and 2000. Mean age (± standard deviation) was 64.9± 10.7 years. Women comprised 59.5% of the patients. Fifty- three patients (27.9% ) had unilateral field loss. The 137 patients with bilateral field loss were older than those with unilateral field loss: 65.7 versus 62.3 years of age (P< 0.05). Mean untreated diurnal intraocular pressures were similar between the eyes of the bilateral patients (mean, 15.5 mmHg in both eyes) and unilateral patients (mean, 16.0 mmHg in field loss vs. 15.6 mmHg in fellow eyes). Visual field mean deviation for all eyes was- 5.4± 4.7 decibels. Central corneal thickness in 168 phakic patients was 543± 35 μ m (range,435- 655 μ m); thickness was less than 500 μ m in 15 eyes and was more than 600 μ m in 11 eyes. Mean vertical cup- to- d.s. ratio for all eyes was 0.67± 0.15. Unilateral field loss patients had a larger cupto- d.s. ratio in the field loss eye (0.75± 0.12) than the fello weye with a normal field (0.60± 0.17, P< 0.0