連続調節持続時間測定法による凝視時間の基礎的研究（第6報）—視疲労からみた横書と縦書の検討について

Studies on the gazing time by the measurement of duration of accomodation (6 th report):Criticism on vertical and crosswise writing the vlew point of eye fatigue

1．緒言

　先に私は連続調節持続時間測定法（水川・高木氏凝視法）^1）による凝視時間は，他の視機能を用うる疲労測定法より鋭敏に全身，特に視機能の疲労を表現し，かつ凝視時間は調節の大きさも含めた毛様筋の耐性検査であるために，近業の持続の難易の尺度となることを認めた^{2）3）4）5）}。

　今回は此の凝視法の実際的応用面での利用度を調べるために，現今尚論点となつている横書，縦書の問題の解明に応用してみた。

Deferences between vertical and crosswise writing in the view point of eye fatigue in works were investigated measuring duration time of accomodation (Mizukawa and Takagi's gazing time method) and measuring range of near point. Marks ranged crosswise gave longer gazing time than those ranged in a calumn and the same trend was observed in Kraepelin's test, in which the range of near point was short. Further after the load with marks moving lengthwise and crosswise, the latter shortened the gazing time less than the former, and the range of near point was shorter, too.