外眼筋筋電図による読書時の眼球運動の分析

Electromyographic analysis of extraocular muscles during reading

目的：読書時における外眼筋の電気生理学的検討。対象と方法：健常成人2名を対象とした。年齢は24歳と25歳，裸眼視力は1.5であった。横書きの文章を眼前40cmに保持して読ませ，その際の両眼の水平筋の筋電図と眼球電図とを記録した。結果：眼球電図はsaccadeと固視の繰り返しによる階段状波形を呈した。筋電図ではsaccadeの発現時に各眼の作動筋に高頻度バースト放電が生じ，固視時には定振幅で持続性の放電があった。結論：筋電図にはpulse-step dischargeを反映した電気的活動があり，読書時の眼位と眼球運動の基本的な出力パターンが記録できた。

Purpose：To analyze the electrophysiologic activity of extraocular muscles during reading. Subjects and Methods：This experimental study was made on two healthy adults,aged 24 and 25 years respectively. They were asked to read horizontally printed sentences held 40cm from the eyes. Electromyogram（EMG）and electro-oculogram（EOG）were simultaneously recorded during reading. Results：EOG during reading consisted of repetitions of saccades of gaze shift and fixation on words,resulting in staircase pattern. EMG showed high-frequency burst discharges synchronous with saccades recorded in the agonistic muscles in both eyes. Sustained discharges of constant amplitude were generated during fixation. Conclusion：EMG during reading showed pulse-step discharges. It was possible to record basic output patterns of eye position and movement during reading.