Binocular, accommodative and oculomotor alterations in multiple sclerosis

Abstract

AbstractMultiple sclerosis (MS) is an acquired demyelinating and inflammatory neurodegenerative disease affecting the central nervous system (CNS). Clinical and subclinical ocular disturbances occur in almost all patients with MS. Among them, oculomotor, accommodative and binocular alterations have been reported in MS. Our research group has conducted a complete analysis of the visual and oculomotor function in several researches with MS patients conducted in the last 4 years, obtaining a characterization of some visual aspects of the patient with MS. Concerning the binocular function, several alterations have been detected in MS patients, with divergence at near distance and stereopsis the most affected parameters. Likewise, MS patients with previous optic neuritis present worse binocular vision. Symptomatology compatible with convergence insufficiency measured with the CISS (Convergence Insufficiency Symptom Survey) is frequently reported by MS patients, but not supported by signs that show clear trend to esophoria at near. This discrepancy between the signs and symptoms could be due to the peculiarities of the CISS questionnaire, including items that are also related to the cognitive function and other ocular abnormalities.Oculomotor alterations have been reported also in patients with multiple sclerosis (MS), especially saccadic dysfunctions. The indirect analysis of horizontal saccades with the Developmental Eye Movement (DEM) and King‐Devick tests shows that are affected by MS, with more level of alteration if there has been a previous episode of optic neuritis. Similar findings have been also reported by other authors using objective eye tracking or video‐oculographic systems. Specifically, the most reported saccadic alterations in advanced MS and clinically isolated syndrome (CIS) are saccadic dysmetry (41.7%) and impaired smooth pursuit (42.3%), which relates to prolonged saccadic latency, no matter if they have suffered or not optic neuritis or internuclear ophthalmoplegia (INO). An increase in saccadic latency has been even found in children with MS. Saccadic initiation time (SI time) and average inter‐saccadic intervals (ISI) are also higher in patients with MS. Furthermore, the first cause of acquired pendular nystagmus is MS.Finally, macular sensitivity measured by microperimetry has been found to be altered in MS patients, especially in eyes with previous optic neuritis. Likewise, a fixational instability characterized also my microperimetry is present in MS patients with optic neuritis, with more increase of the vertical axis of the fixation area than of the horizontal. The ratio of the disease also affects the patient fixation pattern.