Understanding Factors Contributing to Glaucoma in Populations of African Descent

Glaucoma is the leading cause of irreversible blindness globally, with the commonest subtype being primary open angle glaucoma (POAG). POAG is characterised by an increase in intraocular pressure (IOP), optic nerve damage and irreversible visual field loss. People of African descent (AD) are significantly more susceptible to POAG when compared to people of European descent (ED), and the reasons for this are complex and multifaceted. The vast level of genetic diversity in AD populations has allowed, through genome-wide association studies (GWAS), for the identification of several single nucleotide polymorphisms (SNPs) as well as differences in mitochondrial haplogroups, which could explain the pathophysiology underlying the increased susceptibility of AD populations to POAG. The altered expression of genes such as MYOC as well as the expression of inflammatory mediators influencing reactive astrocytes have also been implicated. There are also several differences in morphology between AD and ED eyes which must be considered, including differences in central corneal thickness (CCT) and corneal hysteresis (CH) as well as variation in properties of optic discs. The link between all the aforementioned factors and the increased prevalence of POAG in AD populations will be explored in this review.