Saccadic abnormalities and clinical significance in patients with neuromyelitis optica spectrum disorder

Objective: To characterize the ocular saccadic abnormality in neuromyelitis optica spectrum disorder (NMOSD) patients, and explore the relationship between ocular saccadic abnormality and the overall disability and visual function state. Methods: For the 110 consecutive NMOSD patients who visited the Department of Neurology of Beijing Tongren Hospital from July 2015 to July 2017, a 120 Hz spatial resolution infrared video nystagmus system was used to perform a quantitative horizontal saccade examination. All patients were assessed for overall disability status using the extended disability status scale (EDSS). The subjective visual function status was evaluated using the National Eye Institute-Visual Function Questionnaire (NEI-VFQ 25) and the 10-item neuro-ophthalmic supplement questionnaire (Suppl. 10). Results: A total of 68 (61.8%) of 110 NMOSD patients had horizontal saccadic abnormalities, including 50 cases (45.5%) with abnormal saccade latency, 34 cases (30.9%) with abnormal saccade accuracy and 22 cases (20.0%) with abnormal speed. Patients with abnormal saccade had more intracranial lesions and higher EDSS scores than those with normal eye movements (P=0.006 and P<0.001, respectively). Patients with abnormal saccade had lower Supp.10 scores than the normal patient (P=0.004), while there was no significant difference of NEI-VFQ 25 scores between the two groups (P=0.079). Conclusions: The horizontal saccadic abnormality is common in the NMOSD patients, and the overall disability status and visual function-related quality of life are worse. Quantitative horizontal saccade examination can provide important information on intracranial lesions and neuronal function impairment, and thus it should be emphasized in clinical settings.