Erythrocyte parameters and their associations with glaucoma

Abstract

Purpose : Anemia may contribute to increased local hypoxia, leading to optic nerve head cupping seen in glaucoma. The purpose of this study was to examine possible associations between erythrocyte parameters and glaucoma in a nationally representative sample of non-institutionalized civilian adults in the United States.

Methods : This was a cross-sectional study of participants in the 2005-2008 National Health and Nutrition Examination Survey (NHANES) dataset who had optic disc photos and erythrocyte parameter laboratory tests performed, including hemoglobin concentration (Hgb), Hematocrit concentration (Hct), and red blood cell count (RBC). A binary variable for anemia was also created based on sex specific Hgb cutoffs defined by the World Health Organization (WHO). The outcome of interest was diagnosis of glaucoma based on ophthalmologist grading of optic disc photos for characteristic features of glaucoma. Logistic regression modeling was performed to assess for associations between each of the individual erythrocyte parameters and glaucoma, controlling for demographic information, including age and race/ethnicity. All analyses were weighted according to the NHANES multistage sampling design.

Results : A total of 4,396 sampled participants were included, of whom 41 had prevalent glaucoma (0.9%). The sample represented a weighted estimate of 90,577,744 participants with a weighted glaucoma prevalence of 0.5%. After adjusting for covariates, a 1 gram/deciliter increase in Hgb resulted in a 26% reduction in odds of glaucoma (odds ratio [OR]: 0.74, 95% confidence interval [CI]: 0.63-0.88), a 1% increase in Hct resulted in a 10% reduction in odds of glaucoma (OR: 0.90, 95% CI: 0.84-0.97), and a 1 million cell increase in RBC resulted in a 68% reduction in odds of glaucoma (OR: 0.32, 95% CI: 0.17-0.60). The presence of anemia was associated with a non-significant 2.26 increased odds of glaucoma (OR: 2.26, 95% CI: 0.76-6.71) after adjusting for covariates.

Conclusions : In the 2005-2008 NHANES adult population, increases in erythrocyte parameters (Hgb, Hct, RBC) are associated with decreased odds of glaucoma; however, the presence of anemia is not statistically significantly associated with glaucoma. It may be that the WHO cutoff value for anemia does not have direct impact on the pathogenesis of glaucoma. Further population-based studies are needed to examine associations between additional erythrocyte parameters and glaucoma.

This is a 2021 ARVO Annual Meeting abstract.