This is a cross sectional study built to compare samples from glaucoma patients undergoing surgery (open-angle glaucoma and normal-tension glaucoma, age and gender matched) with age and gender-matched controls (healthy patients undergoing cataract surgery). For this the investigators will collect plasma, urine and aqueous humor to be analyzed through mass spectrometry and nuclear magnetic resonance spectroscopy. Patients have a night fasting period prior to sample collection, and a lifestyle and food frequency questionnaire is filled to control for nutritional influence on metabolites. Diabetic patients are excluded, since it would confound our analysis.
