Oxidative Stress in the Aqueous Humor of Primary Open Angle Glaucoma Patients

Abstract

Purpose:: This study deals with analyzing the oxidative and antioxidant activity in the aqueous humor of primary open angle glaucoma (POAG) patients programmed for anti glaucomatous surgery according to ophthalmological criteria.

Methods:: The aqueous humor was obtained from suitable patients of both sexes (aged 41-90 years) distributed into two groups: 1) Group of 208 POAG patients and 2) comparative group of 284 individuals operated of cataracts (CG). Samples were taken at the onset of surgical manoeuvres, frozen (-85ºC) and stored until processing. Biochemical assays for determining lipid peroxidation by products [malondialdehyde (MDA) measured by the thiobarbituric acid reactive substances (TBARS) test], and antioxidant activity [total reactive antioxidant (TRA); superoxide dismutase (SOD) and glutathione peroxidase (GPx)] were carried out. Data were statistically processed and comparison between groups was done by using the Student t test. Confidence intervals were taken at 95%.

Results:: Oxidative activity (MDA-TBARS levels) was significantly higher (p<0,001) in the aqueous humour from the POAG patients than in the CG. Significantly lower values of the TRA (p<0,001), but higher SOD (p<0,05) and GPx (p<0,05) levels were found in the POAG samples, as related to the comparative ones.

Conclusions:: Oxidative stress, as a result of the dysbalance between pro-oxidant and antioxidant activities, was demonstrated in the glaucoma patients. Probably inflammation- and/or hypoxia-induced-oxidative stress may modulate aqueous humour outflow. The possibility remains that antioxidant supplementation may benefit the glaucoma cases specifically displaying lower TRA capacity in the described laboratory probes.

Keywords: oxidation/oxidative or free radical damage • antioxidants • visual impairment: neuro-ophthalmological disease