Color vision versus pattern visual evoked potentials in the assessment of subclinical optic pathway involvement in multiple sclerosis

BACKGROUND: Optic pathway involvement in multiple sclerosis is frequently the initial sign in the disease process. In most clinical applications, pattern visual evoked potential (PVEP) is used in the assessment of optic pathway involvement. OBJECTIVE: To question the value of PVEP against color vision assessment in the diagnosis of subclinical optic pathway involvement. MATERIALS AND METHODS: This prospective, cross-sectional study included 20 multiple sclerosis patients without a history of optic neuritis, and 20 healthy control subjects. Farnsworth-Munsell (FM) 100-Hue testing and PVEPs to 60-min arc and 15-min arc checks by using Roland-Consult RetiScan(®) system were performed. P(100) amplitude, P(100) latency in PVEP and total error scores (TES) in FM 100-Hue test were assessed. RESULTS: Expanded Disability Status Scale score and the time from diagnosis were 2.21 ± 2.53 (ranging from 0 to 7) and 4.1 ± 4.4 years. MS group showed significantly delayed P(100) latency for both checks (P < 0.001). Similarly, MS patients had significantly increased total error scores (TES) in FM-100 Hue (P < 0.001). The correlations between TESs and PVEP amplitudes / latencies were insignificant for both checks (P > 0.05 for all). 14 MS patients (70%) had an increased TESs in FM-100 Hue, 11 (55%) MS patients had delayed P(100) latency and 9 (45%) had reduced P(100) amplitude. The areas under the ROC curves were 0.944 for FM-100 Hue test, 0.753 for P(100) latency, and 0.173 for P(100) amplitude. CONCLUSIONS: Color vision testing seems to be more sensitive than PVEP in detecting subclinical visual pathway involvement in MS.