Retinal visual acuity with pattern VEP normal subjects and reproducibility.

Retinal visual acuity was determined using an objective method by means of VEP. Sixty subjects with subjective visual acuity ranging from 20/25 to 20/12 were measured with a computer-controlled laser interferometer, using interference fringes modulated in counterphase as pattern-reversal stimulus. Steady-state VEPs taken at different spatial frequencies were evaluated by Fourier analysis and linear regression. Objective retinal acuity was calculated as the intersection between the linear regression line and the linear scaled spatial frequency axis. In 68% of all cases, the difference between objective and subjective visual acuity was less than +/- 5.1 cycles per degree (c/d) (+/- 15.4% referred to subjective acuity); in 86%, the difference was less than +/- 7.7 c/d (+/- 23.1%).