We know that many factors influence the emergence of a disease. Apart from the susceptibility of the individual there are accidents of environment which may entirely determine the situation, as, for example, the possibility of contracting malaria only in the zone of the geographic distribution of the Anopheles mosquito.
It is now recognized that in the study of a disease we must include more than an account of its pathology. The etiology should embrace a knowledge of its distribution, and this may necessitate a detailed study of the race and culture of the affected individuals. If this is begun now we have an opportunity of solving some of our problems. Soon, because of the spread of our type of civilization, it will be too late. For example, we still list glaucoma simplex as a disease of unknown cause. We understand fairly well the mechanics of its production, but we are
MANN I. Geographic OphthalmologyA Review of the Possibilities. Arch Ophthalmol. 1964;72(5):632-636. doi:10.1001/archopht.1964.00970020632009