Vision screening of illiterate populations.

To assess the amount of reduced vision in a population is an important public health matter, especially in areas where blinding diseases are endemic. Testing visual acuity is, however, a complex problem when a major part of the population is illiterate. The best-known test of vision is the E-test, but this produces the problem of untestability in illiterate populations.The introduction of the Sjögren hand-test as an alternative to the E-test for vision screening of unselected illiterate populations in West Africa resulted in a highly significant reduction of untestability. For certain vision levels it is possible to correlate the results of the hand-test directly with those of the E-test. The hand-test is less well defined than the E-test, but has important advantages for the purpose of vision screening of illiterate populations.