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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 glaucomaaffected patients using standard filtration surgery. Twentyone specimens from healthy eyes collected for cornea transplants serve as controls. Oxidative DNA damage was evaluated by determining 8-hydroxy-2Ј-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-2Ј-deoxyguano-sine 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.

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Purpose: The aim of the present paper is to describe the variations in intraocular pressure (IOP) during the day in normals, in patients with primary open-angle glaucoma (POAG) and in patients with normal-tension glaucoma (NTG). IOP represents one of the most important risk factors for glaucoma. However the IOP value is not constant during the day and IOP fluctuation could influence the diagnostic and prognostic evaluation of the glaucomatous disease. Methods: For this purpose IOP was evaluated every 2 h from 8 a.m. to 8 p.m. in one randomized eye of 33 normal subjects, 95 POAG and 50 NTG patients. Results: The results show that the highest IOP values were detectable in the morning in all three groups. The lowest values were found in the early afternoon hours. These variations were most evident in POAG patients. The daily IOP fluctuations were directly proportional to IOP level. Conclusion: The study evidents that a single tonometric evaluation, especially if done in the first hours of the afternoon, is not sufficient to correctly evaluate the IOP-related risk in glaucoma patients. If the pressure peaks are important in determining the extent of glaucomatous damage in NTG patients IOP should not have an important role in optic nerve head damage. The use of diurnal curves seems to be mandatory for the assessment of IOP-related risk and of efficiency of the therapeutic approach.

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Because the cornea and iris are directly exposed to light, they possess antioxidant defense mechanisms that are not activated in the trabecular meshwork. The peculiar sensitivity of the trabecular meshwork to oxidative stress is consistent with the damage selectively induced in it, triggering glaucoma's pathogenic cascade.