Is Optical Coherence Tomography Really a New Biomarker Candidate in Multiple Sclerosis? A Structural and Functional Evaluation

To assess the structural and functional status of patients with multiple sclerosis (MS) without a history of optic neuritis. Thirty-nine patients with MS who had reported no visual symptoms before and after the time of MS diagnosis were included. Thirty-eight healthy subjects were included as a control group. Retinal nerve fiber layer (RNFL) thickness was determined by optical coherence tomography. Pattern visual evoked potentials (PVEP), full-field electroretinogram (ERG), and multifocal electroretinogram (mfERG) were performed. There was a significant reduction (P = 0.011) only in temporal RNFL thickness in patients with MS. P(100) latency was significantly delayed with both 60-min arc checks (P < 0.001) and 15-min arc checks (P < 0.001); however, P(100) amplitude was significantly reduced only in 60-min arc checks (P = 0.026). Rod response b-wave implicit time and standard combined response a- and b-wave implicit times were significantly delayed in patients with MS. Patients with MS with a delayed P(100) latency (21/39; 53.8%) had significantly reduced cone response b-wave amplitude and significantly delayed cone response a- and b-wave implicit times in ERG. mfERG results did not differ between MS and control subjects and between patients with a delayed and a normal P(100) latency. Pearson correlations between RNFL thickness and P(100) amplitude and latency in patients with MS were not significant (P > 0.05). There is no correlation between RNFL thickness and P(100) response in patients with MS. PVEP seems to be a more reliable biomarker in determining visual pathway involvement in patients with no history of optic neuritis.