Tactile acuity, aging, and Braille reading in long-term blindness

Tactile acuity came under investigation in 69 blind and 69 age-matched, sighted adults. Measures comprised thresholds for discriminating gaps, length (lines), and orientation (along vs. across the finger). Acuity of blind and sighted participants' index fingertip declined as a function of age at the same rate: roughly 1% threshold rise per annum. Slower braille reading paralleled this decline, as assessed with a tactile adaptation of the Tinker-Carver test. From youths to elders, however, blind participants outperformed sighted participants with the fingertip but not the lip, a site of commensurate acuity. Experimental trials of enlarged braille and development of a tactile Snellen-type chart for screening of acuity-related difficulty suggest themselves as promising applications.