Ethnicity and glaucoma: higher environmental temperatures may accelerate the onset, and increase the prevalence, of primary open-angle glaucoma.

Publications on the age-related prevalence of primary open-angle glaucoma (POAG) show that African and African-descended patients and others living in warm climates present a higher prevalence of POAG than do those in temperate zones. The data have been analysed in order to discover whether temperature plays a role. The relation between AOO, the youngest age diagnosed with POAG, and prevalence has also been examined. Prevalences at the age of 70 years P(70) were calculated from logarithmic plots, and logP(70), plotted as a function of the average monthly maximum temperature T degrees C, and tested with the LINEST programme. AOO declined, but logP(70) rose, with T degrees C. The data are consistent with the view that high temperatures accelerate the onset, and increase the prevalence, of POAG. A consideration of evolution suggests that the reduced Caucasian prevalence may result from originally African tribes migrating to locations with more temperate climates: this would have caused a constriction of superficial capillaries to preserve body heat; hence the aqueous outflow channels might dilate, and reduce a predisposition for POAG. Suggestions are made for testing the hypothesis.