The visual pathway as a model to understand brain damage in multiple sclerosis EH Martínez-Lapiscina, B Sanchez-Dalmau, E Fraga-Pumar, S Ortiz-Perez, AI Tercero-Uribe, R Torres-Torres and P Villoslada

Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant. The visual pathway represents a model of acute focal central nervous system (CNS) damage, through acute optic neuritis and retinal periphlebitis, as well as a model of chronic, diffuse CNS damage through chronic retinopathy and optic neuropathy. The optic pathway can be accurately evaluated in detail, due to the availability of highly sen- sitive imaging techniques (e.g. magnetic resonance imaging or optical coherent tomography) or electro- physiological tests (multifocal visual evoked potentials or electroretinography). These techniques allow the interactions between the different processes at play to be evaluated, such as inflammation, demyelin- ation, axonal damage and neurodegeneration. Moreover, these features mean that the visual pathway can be used as a model to test new neuroprotective or regenerative therapies.