Over the past 30 years, a number of techniques for the objective measurement of visual acuity using various optokinetic responses have been proposed. Perhaps the best known of these methods is that of Ohm.1
Ohm uses optokinetic nystagmus induced by moving stripes, and the inhibition of the induced nystagmus by a fixation point (or pattern of fixation points) to measure visual acuity. Visual acuity, by this method, is defined as the visual angle of the smallest fixation point which inhibits the optokinetic nystagmus. As such it is a measure of minimum visible rather than minimum separable acuity.
Goldmann2 and Schmidt3 use an induced pendular nystagmus which is elicited by a swinging plate with a checkerboard pattern which passes behind a cut-out window. Visual acuity in this system is actually measured by the maximum viewing distance at which the pendular eye movements can be induced by the stimulus
WOLIN LR, DILLMAN A. Objective Measurement of Visual AcuityUsing Optokinetic Nystagmus and Electro-Oculography. Arch Ophthalmol. 1964;71(6):822-826. doi:10.1001/archopht.1964.00970010838008