Temporal aspects of visual perception in demyelinative diseases

The study aims to test whether impaired conduction velocities following optic neuritis (ON) serve as a limiting factor on various temporal, as compared to static, aspects of vision. Critical Flicker fusion frequency (CFFF), two motion perception tasks (object and number-from-motion extraction tasks), high and low contrast acuities, and visual evoked potentials (VEPs) were assessed in 23 ON patients. Strong correlations were found between the various dynamic visual function scores. Furthermore, regression models revealed that each of the dynamic visual functions significantly predicted VEP latencies. These findings were specific to patients' affected eyes and were not evident for static visual functions. Fellow eyes' VEP latencies were best predicted by the VEP latencies of the affected eyes. The similar impact of VEP latencies on various dynamic visual functions suggests conduction velocity to be the common limiting factor for temporal-related visual perceptual abilities. The specificity of these findings to the patients' affected eyes and to dynamic visual functions highlights the precision of dynamic visual functions for identifying demyelinative attack. Prolonged VEP latencies in the fellow eyes seem to stem from different patho-physiological processes. The hypothesis that inter-eye synchronization in conduction latencies is important to accomplish visual processing (binocular vision) is further discussed.