Visual acuity tests for near: implications and correlations.

Near vision has been studied from many aspects. Galton, in 1885, tested the farthest distance at which four-point type could be read in 7,000 persons, from six to 81 years of age. He concluded that the near visual acuity improved rapidly from childhood to a maximum at the age of 20 years, then de­ clined very gradually till the age of 45 years, and more rapidly thereafter. Chapanis, in 1950, checked the visual acuity of 574 per­ sons from seven to 77 years of age with a reduced Snellen chart at 32 inches and like­ wise found a curvilinear trend with the high­ est score in the 15 to 20-year-old group. In subjects corrected for errors of refrac­ tion and accommodation a close correspon­ dence exists between the visual acuity at 20 feet and that at reading distance (Bjerke, Landolt, Snell) with these exceptions (Kestenbaum and Sturman): Near vision may be better than that for distance in those with peripheral opacities of cornea or lens, irregular astigmatism, or pendular nystag­ mus—because of pupillary constriction or convergence, respectively. Near vision is usually poorer than far vision in the presence of a central opacity of the cornea or lens, or of an incomplete central scotoma.