Objective assessment of visual acuity by induction of optokinetic nystagmus.

Optokinetic nystagmus is the term applied to the nystagmus evoked by a succession of moving objects passing before the eyes (Brain, 1962). It has proved useful as a diagnostic tool in the examination of patients with neurological disease (Cogan, 1956; Huber, 1961; Smith, 1963; Walsh, 1957). Methods of inducing and suppressing optokinetic nystagmus have also been used as the basis for objective testing of the visual acuity (Dayton, Jones, Aiu, Rawson, Steele and Rose, 1964; Goldmann, 1943; Gorman, Cogan, and Gellis, 1957; Kiff and Lepard, 1966; Ohm, 1953; Reinecke and Cogan, 1958; Schmidt, 1956; Schwarting, 1954; Tauber and Koffler, 1966; Voipio, 1961; Wolin and Dillman, 1964). However, none of these methods of assessing visual acuity has become generally established for routine testing largely because of the complexity of the apparatus. The technique to be described is simple to perform and gives rapid and acceptable results.