Refractive status of indigenous people in the Amazon region of Brazil

This interesting study investigated the vision of the illiterate indigenous people of the upper Rio Negro region of the Amazon rain forest in northwestern Brazil.

Researchers studied the vision of 486 people, 259 of whom were indigenous people, between 12 and 59 years of age. The subjects were considered to be indigenous if there were at least three generations of indigenous ancestry with no folkloric suggestion of other ancestors.

Nearsightedness was rare among, only 2.7% of the indigenous subjects, had nearsightedness of -1.00 D or more and 1.6% (four people) had bilateral nearsightedness of -1.00 D or more.

Those 2.7% and 1.6% of the subjects with myopia were the only educated indigenous people examined. The other Brazilians included in the study had higher rates of nearsightedness (6.4% of eyes and 5.1% of subjects bilaterally). Of these, the older less-educated adults had a very low prevalence of nearsightedness (3.2% of eyes and 2.0% of subjects), whereas the younger, slightly educated Brazilians had a higher prevalence of Nearsightedness (11.3% of eyes and 9.7% of subjects).

The low amount of myopia in the illiterate indigenous people is consistent with other studies and suggests that myopia is related to literacy and all that comes with literacy. The generational change among the local mixed race Brazilians further supports this conclusion.

Published: Optom Vis Sci. 2005 Apr;82(4):267-72

Researchers: Thorn F, Cruz AA, Machado AJ, Carvalho RA.
New England College of Optometry, Boston, Massachusetts