This study is designed as an open label evaluation of the efficacy of latanoprost and timolol fixed combination (Xalacom) after 6 month of treatment. Eligible patients may be enrolled at the baseline visit. All current ocular hypotensive therapy must be discontinued at this time. On baseline day, patients eligible for the study will receive Xalacom which is to be instilled in the morning.

Inclusion Criteria:

• Diagnosis of glaucoma (primary open angle, pigmentary, exfoliative) or ocular hypertension (IOP >= 21 mmHG).
• Visual acuity >= 20/200.

Exclusion Criteria:

• Closed/barely open anterior chamber angle or history of acute angle closure glaucoma.
• Hystory of ALT within 3 months prior to the baseline visit.
• History of any ocular filtering surgical intervention.
• Ocular surgery or inflammation/infection within 3 months prior to the baseline visit.