Study and Treatment of Visual Dysfunction and Motor Fatigue in Multiple Sclerosis

Primary fatigue represents a major cause of disability in patients with multiple sclerosis (MS), being reported in about 90% of cases. Fatigue interferes with everyday functioning but, unfortunately, little is known about its mechanisms. The investigators propose a characteristic eye movement abnormality (internuclear ophthalmoparesis, INO), commonly encountered in MS, as a simple model for primary motor fatigue. The investigators described worsening of ocular performance in MS patients with INO following visual tasks (ocular motor fatigue), which is likely due to decreased neural conduction along brain pathways injured by MS. This mechanism could represent a major component of MS-related primary motor fatigue. Relevant to Veterans' care, INO is a significant cause of visual disability, especially when complicated by ocular fatigue, and limits daily activities such as reading and driving. The investigators propose a medical treatment to improve ocular performance/fatigue in INO, which can reduce visual disability and improve quality of life in Veterans with MS.