Summary: Objective: To evaluate the intensity of oxidative molecular damage and its clinical correlations: visual field damage, intraocular pressure, age, and disease duration. Methods: DNA was extracted from human trabecular meshwork specimens collected from 17 glaucoma-affected patients using standard filtration surgery. Twenty-one specimens from healthy eyes collected for cornea transplants serve as controls. Oxidative DNA damage was evaluated by determining 8-hydroxy-2′-deoxyguanosine levels. All patients underwent a Humphrey 30-2 visual field examination and diurnal tonometry before surgery. Results: The mean +/- SD DNA oxidative damage was 8.51 +/- 5.44 and 1.75 +/- 1.80 8-hydroxy-2′-deoxyguanosine molecules/10(5) normal nucleotides in patients with glaucoma and controls, respectively. A statistically significant correlation was found among human trabecular meshwork DNA oxidative damage, visual field damage, and intraocular pressure. No other statistically significant correlations were found. Conclusions: Oxidative stress may represent an important pathogenetic step in primary open-angle glaucoma because it could induce human trabecular meshwork degeneration, favoring an intraocular pressure increase, thus priming the glaucoma pathogenetic cascade.