A review of the literature and a normative study of accommodative facility.

Although many different authors have proposed accommodative facility standards, there is little agreement as to what should constitute "normal" accommodative facility. To establish a norm, 100 adult subjects were tested using a vectographic viewing device which was placed 40 cm from 20/30 letters. The letters were viewed alternately with +/- 2.00 D lenses, first monocularly, and then binocularly. The subjects were screened and known to be nonpresbyopic, nonstrabismic, corrected to 20/30 monocularly, and with adequate binocularity. The study found a mean accommodative facility of 11.59 OD, 11.09 OS, and 7.72 cpm binocularly. These findings can be used as a clinical guide by which to evaluate a patient's accommodative facility findings.