Association of total antioxidants level with glaucoma type and severity

OBJECTIVES To compare the mean total antioxidant status (TAS) among 3 glaucoma types, namely: pseudoexfoliation glaucoma (PEG), primary open angle glaucoma (POAG), and primary angle closure glaucoma (PACG), and study its potential association with various clinical glaucoma-parameters.   METHODS In this case-control study, plasma samples were obtained between September 2013 and October 2014 from 340 glaucoma patients (PEG [n=54]; POAG [n=147]; PACG [n=139]), and 351 controls of matching age, gender, ethnicity, and 5 different systemic co-morbidities from King Abdulaziz University Hospital, Riyadh, Saudi Arabia. The TAS in all samples was determined by a colorimetric-based assay.   RESULTS The mean±standard deviation of TAS was significantly lower among cases: 0.77±0.32  than controls: 1.1±0.22, p less than 0.0001. Moreover, the TAS levels were significantly different across the 3 types of glaucoma: 0.86±0.24 in PEG, 0.47±0.32 in POAG, and 0.98±0.41 in PACG (all p less than 0.0001). In addition, there was a significant correlation between TAS and age at onset (Pearson correlation coefficient [R] 0.17, p less than 0.0001), cup/disc ratio (R: -0.13, p=0.004), and number of anti-glaucoma medications (R: -0.16, p=0.001).   CONCLUSION Our findings provide evidence that plasma TAS levels are decreased in patients with glaucoma, more so in POAG and PEG than PACG, supporting the hypothesis that decreased antioxidative defense and/or increased oxidative stress may have a critical role in the pathogenesis of glaucoma.