Effect of induced blur on visual acuity and stereoacuity

The acuities of three subjects with good visual acuity and stereoacuity were reduced by the addition of diffusing filters placed before one or both eyes; these subjects then underwent automated stereoacuity and visual acuity tests. Results were idiosyncratic and differed from subject to subject to such an extent that no general rule sufficed to describe the effect of different degrees of blur on visual acuity and stereoacuity. It had been thought that blur degraded stereoacuity more than visual acuity but most of the results from one subject indicated the opposite effect. The effects of monocular vs. binocular blur are discussed.