[Optic neuritis, multiple sclerosis-related or not: structural and functional study]

Multiple sclerosis (MS) is an inflammatory demyelinating disease with axonal degeneration. Optical coherence tomography (OCT) is a noninvasive technique that quantifies the thickness of the retinal nerve fiber layer (RNFL). The objectives of this study are: to determine the thickness of the RNFL in MS patients with or without previous optic neuritis (ON) and in patients with ON and to determine the relationship between the structural damage and functional alterations in visual acuity (VA) and visual field (VF).

Three groups were studied: G1 - patients with ON, G2 - patients with MS and ON, and G3 - patients with MS and without previous ON. Ophthalmological (VA, VF, OCT) and neurological examinations were performed.

OCT thickness in the unaffected eye was significantly thicker in ON patients (103.99) than in the other groups, however there was no differences among the affected eyes. There were significant differences in VA and VF among the non-affected eyes (p = 0.007), but not among the affected eyes (p = 0.878).

All MS patients showed axonal damage in both optic nerves, more in patients with previous ON. Axonal damage was detected early, so OCT could be used as a structural biomarker. Structural damage was related with the functional alterations.