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