ACCOMMODATION POWER DETERMINED WITH VISUAL-EVOKED CORTICAL POTENTIALSIN PSYCHOGENIC VISUAL DISTURBANCES

Accommodation power was measured with pattern visual evoked potentials in 12 normal subjects and three patients suffering from psychogenic v isual disturbances and accommodation failure. Steady-state visual evok ed cortical potentials recorded by increasing a minus-power lens in fr ont of the eye in 1 diopter steps. The regression line was established from the visual evoked cortical potential amplitudes vs accommodation stimulus plot, and the objective accommodation power was determined b y extrapolating the line to zero amplitude. The accommodation power me asured by visual evoked cortical potentials was larger by approximatel y 2 diopters than that obtained subjectively by near-point rule in nor mal subjects. The subjective accommodation power was remarkably low fo r their age in each patient but the objective power was normal. These results suggest that the decrease of accommodation in these patients w as caused by psychogenic mechanisms, and visual evoked cortical potent ial measurements of accommodation could provide helpful information fo r diagnosis.