觀看電腦螢幕顯示器對於視覺敏銳度、認知記憶力以及疲勞、舒適程度的影響

Abstract

電腦螢幕普遍使用LED 做為背光模組，已有研究指出LED 的光波長較短、能量偏高，且光譜中含有較高比例的藍色光。暴露此光源容易增加得到眼部疾病的風險，也容易造成眼睛疲勞。本研究欲了解長時間電腦螢幕觀看作業是否會對視覺敏銳度、視覺認知記憶力以及視覺舒適與疲勞程度造成影響；以及了解藍光對於視覺表現的可能影響。研究個案排除色盲、色弱者或有重大眼疾者，而矯正後為標準視力者則不在此限。測驗包含三大面向：視覺敏銳度、視覺認知記憶力與視覺疲勞舒適程度。視覺敏銳度測驗使用紙本的視力表以及視覺對比度表；視覺認知記憶力測驗使用色棋以及維也納追蹤系統(Vienna Test System)；而視覺疲勞舒適程度測試則使用閃光融合閾值儀以及兩份主觀評量問卷。在視覺表現方面，本研究在視覺認知記憶力測試的色棋錯誤分數結果中發現受試者在2小時長時間電腦螢幕觀看作業後，其色棋錯誤分數降低且達統計上的顯著差異(p=0.032)。雖然主觀問卷以及閃光融合閾值的前後測結果未達顯著差異，但從問卷中的評分中得知受試者在2 小時電腦螢幕觀看作業後的主觀疲勞徵狀較半小時短時間作業明顯。另外，在環境光源與電腦光源的光譜分布比例上，亦得知電腦光源之藍光光譜分布比例較環境光源高。本研究結果推論，LED 電腦螢幕所發射出的藍色光譜在2小時測試期間內仍會使受試者的警醒度提升，進而使視覺認知記憶力表現較佳。 但由於眼部肌肉高頻率的收縮，以及暴露時間的延長，導致受試者有明顯之視覺疲勞的情形。綜合研究結果，電腦作業工作者應了解其工作上潛在的視覺負荷風險，工作單位應設置相關措施保障作業人員的健康。

Light emitted diode (LED) backlight is commonly used in computer monitors.Many studies have shown that LED light exhibits shorter wavelength, higher energy and higher proportion of blue light in the spectrum. Exposure to this light source is therefore likely to cause eye fatigue and increase the risk of getting eye diseases. This study first aimed to unveil whether using computer for a long time would have impact on visual sensitivity, cognition memory performance, fatigue and comfort, and, secondly, to explore whether blue light may effect on visual performance. In this study, exclusion criteria for subject recruitment included color blindness, color weak and major eye diseases. However, subjects with vision correction for standard visual acuity were allowed to participate. Moreover, three major aspects were incorporated in the study test,e.g. visual sensitivity, cognition memory performance, fatigue and comfort. Visual acuity test employed vision chart and visual contrast sheet. Visual cognition memory performance applied Munsell 100 Hue test and Vienna test system. Visual fatigue and comfort utilized flicker fusion threshold instrument and two subjective assessment questionnaires. Regarding the visual performance, this study has found that study subjects’ color chess error score decreases significantly after watching computer screen for two straight hours (p=0.032). Although the results in the subjective questionnaire surveys and the flicker fusion threshold test were not significantly different between two-hours and 30-minutes computer-screen-watching periods, the level of fatigue for subjects watching computer screen for two hours was more significant than those of 30 minutes. In addition, based on the ratio of spectral distribution in ambient light source and computer light source, it was concluded that the spectrum distribution of blue light spread more in computer light source than in the ambient light. In the end, this study has found that LED computer screen would enhance subjects’ alertness by way of blue light spectrum over a time span of two hours, therefore reinforce their visual recognition memory performance. However, high-frequency contractions in eye muscles and prolonged exposure time have contributed to the visual fatigue of study subjects. All in all, this study urged that computer screen watching should understand the potential risks of visual loading with their working conditions, and, in the meantime, the workplace requires health-related measures for better visual protection of operators.