Ayyagari et al.1 evaluated the potential association of serum vitamin-D levels and severity of primary open-angle glaucoma in subjects of African descent. They used a subset of the enrollees of the African descent and glaucoma evaluation study III (ADAGES III), comprising a total 357 patients. There were 178 normal controls, 178 early POAG subjects (visual field MD better than -4 dB), and 179 advanced POAG subjects (visual field MD worse than -10 dB). The ADAGES III is a large study of the contributions of genotype to the glaucoma phenotype in those of African descent. The present study found that the mean vitamin-D levels of control subjects (8.02 ± 6.19 pg/ml) and early POAG subjects (7.5± 5.74 pg/ ml) were significantly more than those with the advanced POAG phenotype (6.35 ± 4.76 pg/ml; p=0.0117 and 0.0543, respectively). However, there was no difference when comparing the control versus the early POAG groups (p = 0.8508).
Previous association studies have also found a correlation of low vitamin-D levels and presence of glaucoma or severe glaucoma, notably in a South Korean population study and a French case-control study. The current report is the first to identify this type of link in a population of African descent, a group that has the highest risk for glaucoma. Furthermore, those of African descent are at greater likelihood for deficiencies in vitamin D,2-3 perhaps further exacerbating the risk for glaucoma.
In the larger scheme, vitamin-D deficiency is prevalent in the general population and has been linked to other important disease states such as osteoporosis, cardiovascular disease, diabetes, cancer, autoimmune diseases, depression, and dementia. The latter association is particularly relevant since both dementia and glaucoma are ultimately diseases of neuronal degeneration. More recently, lower levels of vitamin D have also been correlated with possibly greater prevalence and mortality related to the recent COVID-19 pandemic. Although only an association can be shown in this type of study, the information can be very helpful to direct future studies regarding the genetics and mechanism of action by which vitamin D may affect glaucoma progression, as well as serve as a starting point for a potential clinical trial to study whether vitamin D supplementation can be helpful for patients of African descent in preventing glaucoma development and/or progression.