Changes in Near Lateral Phoria and Near Point of Convergence After Viewing Smartphones

스마트폰 시청 후 나타난 근거리 사위 및 폭주근점의 변화

  • Received : 2012.05.02
  • Accepted : 2012.06.16
  • Published : 2012.06.30


Purpose: This study was to compare changes in near lateral phoria and near point of convergence after viewing smartphones and monitors during short periods. Methods: 50 subjects with healthy eyes from 20s to 30s (mean age, $21.84{\pm}5.13$ years) were examined. Viewing time was set at 5 min to 20 min, and recovery time was 10 min. Near lateral phoria and near point of convergence (NPC) were examined before and after watching smartphones and monitors, and subjectively symptoms for visual fatigue were surveyed using a questionnaire before and after viewing image. Results: The tendency of phoria in viewing smartpones found more exophoric results than in viewing monitors, and both exophoric shifts were recovered after 10 min. The receded NPC in the smartphones was more remote than in the monitors. The smartpones induced more visual fatigue than the monitors. Conclusions: Sustained smartphone works induced changes in phoria and NPC, and this type of stress could cause visual fatigue. Therefore, an appropriate rest breaks can be helpful in relieving visual fatigue.


Monitor;Smartphone;Phoria;Near point of convergence


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