Characterizing the Pathobiological Mechanisms of Binocular Acuity Summation versus Inhibition in MS: Central Adaptation or Not?

Research has shown that the 'fellow' unaffected eye, and its afferent visual pathway, in patients with unilateral optic neuritis, can exhibit physiologic changes which synchronize the arrival of visual information within the cortex. This 'temporal reorganization', if confirmed, would represent an important central adaptation for visual processing, with implications for binocular fusion and stereopsis. Recent visual evoked potential studies show prolonged latency in visual cortical responses in both the optic neuritis eye and fellow 'adapting eye.' Detailed analysis revealed a delay in 'time to peak' of the cortical response in the adapting eye, as opposed to a delay in 'time to onset' in the optic neuritis eye. A similar process of central adaptation, may explain the phenomena of binocular summation and inhibition, observed in patients with asymmetric monocular visual acuities. The aim of our study is to analyze the structural and functional measures of the anterior visual system in MS patients exhibiting bin ular summation versus inhibition, to elucidate the pathobiological underpinnings that differentiate these distinctive processes. Additional studies on the influence of body temperature and potassium channel modulation with 4-aminopyridine will be conducted.