TABLE 1.

Studies assessing visual evoked potentials (VEPs) in progressive multiple sclerosis (PMS).

Study	Technique	Cohort	Main findings
Leocani et al., 2006	ff-VEPs	43 RRMS, 28 SPMS, 13 PPMS	VEPs abnormalities significantly more frequent in PMS (92.3% PPMS and 85.7% SPMS) than in RRMS (77.4%)
Kira et al., 1993	ff-VEPs	35 RRMS, 11 PPMS (japanese)	VEPs abnormalities more frequent in PPMS compared to RRMS patients
Stevenson et al., 1999	ff-VEPs	131 PPMS	Visual conduction delay in 105/131 (80%) PPMS patients

ff-VEPs, full-field visual evoked potentials; RRMS, relapsing–remitting multiple sclerosis; SPMS, secondary progressive multiple sclerosis; PPMS, primary progressive multiple sclerosis.