High corneal astigmatism in the adult Navajo population

Corneal astigmatism was measured in 176 unselected Navajo patients over the age of 45 years old. The result was a 4% incidence of with-the-rule astigmatism of two diopters or more in at least one eye. Conjectures on a reason for the small incidence of high corneal astigmatism in the adult Navajo population as compared to the large incidence that occurs in Navajo children is discussed.