Correlation of corpus callosum index and optic coherence tomography findings in multiple sclerosis with or without optic nerve involvement

PURPOSE: To evaluate the correlation of spectral domain optical coherence tomography (SD-OCT) parameters including peripapiller retinal nerve fiber length (RNFL) and ganglion cell layer (GCL) analysis with corpus callosum volumes, which were determined by corpus callosum index (CCI) radiologically in multiple sclerosis (MS) patients.
METHODS: Forty MS patients, with or without optic neuritis in history, were involved in the study on which RNFL and GCL analysis by SD-OCT were performed. Anterior, middle, posterior, and overall CCI were calculated for all subjects on 1.5 T magnetic resonance imaging scans, on conventional best mid-sagittal T1W image.
RESULTS: Seventeen patients had unilateral optic neuritis in history (42.5%) and had significantly lower CCIs compared to cases without optic nerve involvement (p<0.05 for each); lower RNFL measurements and lower GCL values in involved eyes compared to uninvolved side (p=0.03 and p<0.001, respectively). Overall CCI was lower in patients with more attacks in history and in elder MS patients (p=0.011 and p=0.06, respectively). Overall CCI was also lower in cases with lower mean RNFL and mean GCL measurements possessing a high positive correlation coefficient (p=0.047, p=0.002; r=0.316, p=0.478, respectively).
CONCLUSION: This study demonstrated that involvement of optic nerve in MS patients is with lower anterior, middle, posterior, and overall CCI values in addition to lower mean RNFL and GCL values of OCT. The positive correlation of CCIs with OCT parameters shows that the neuroaxonal degeneration in MS simultaneously affects the retina and the brain.