A device has been constructed that permits rapid, repeatable measures of visual acuity while minimizing many of the patient and examiner errors in subjective acuity testing. The Baylor acuity meter utilizes digital logic circuitry to implement a carefully controlled psychophysical "staircase" testing procedure in a small portable unit. Comparisons of the acuity meter with conventional measurement techniques on 51 subjects yield correlations of +.74 and +.81. A test-retest correlation of +.96 was found.
Decker TA, Kuether CL, Williams RE, Logar ND. A Semi-automated Instrument for Determination of Acuity Threshold. Arch Ophthalmol. 1975;93(9):841-844. doi:10.1001/archopht.1975.01010020723011