使用頭戴式虛擬實境裝置對於視覺表現影響

Abstract

頭戴式虛擬實境(head-mounted virtual reality)裝置在近年來多使用於工作場所之教育訓練、校園知識教育工具或跨足健康領域等。其高沉浸感、可操控、可互動、可即時回饋的特點，結合所需之專業能力內容，成為在職場或學校之新興教育、訓練用輔助工具。但使用虛擬實境時，可能出現使用中或使用後的副作用，包括動暈症以及視覺問題。而這些副作用或許和虛擬裝置的軟硬體、使用時的情境及使用者個人特質有關，進而導致使用上的不舒適，甚至對人體造成健康負面效應，也可能造成各個應用領域使用上的阻礙。本研究欲了解在不同時間長度下使用頭戴式虛擬實境裝置是否會對視覺敏銳度、視覺認知記憶力以及視覺疲勞程度造成影響。 本研究使用頭戴式虛擬實境裝置作為硬體，並以重複性測量的研究設計規劃進一步探索暴露於虛擬環境前後人體視覺表現的差異。視覺測驗包含三大面向： (1)視覺敏銳度: 使用紙本的視力表來測試、(2)視覺認知記憶力:使用色棋以及維也納追蹤系統檢測、 (3)視覺疲勞程度: 使用視覺疲勞主觀評量問卷來做評估。 本研究招募30位20-30歲的志願者參加試驗，受試者包含男性9位、女性21位受試者，排除色盲、色弱者或有重大眼疾者，但矯正後為標準視力者則不在此限。受試者需分別參與5分鐘、20分鐘和45分鐘三次不同時間長度虛擬實境遊戲之實驗，並且於每次實驗前後進行視覺表現測驗。受試者參與的第一次實驗均為5分鐘長度的實驗，之後隨機參與第二次及第三次的20分鐘或45分鐘時間長度測驗。每兩次實驗之間至少間隔一個禮拜。 視覺表現方面的研究結果顯示，受試者左右兩眼的視銳度在後測結果比前測結果有些微下降的趨勢，但未達統計上顯著差異。測驗時間45分鐘組中受試者後測的色棋測驗錯誤分數較前測錯誤分數顯著提升(p<0.05)，但後測的色棋測驗使用時間較前測使用時間下降(p<0.05)。同時，測驗時間45分鐘組的受試者，後測之色棋測驗時間分別與視覺追蹤分數呈現顯著負相關(p<0.05)，與視覺追蹤時間呈現顯著正相關(p<0.05)。主觀視覺疲勞問卷調查結果在三組測驗時間長度的組別間無顯著差異。 本研究結果顯示，使用頭戴式虛擬實境裝置會對視覺認知記憶力造成負面影響，而對視覺敏銳度和視覺疲勞程度則無觀察到顯著影響。對此未來研究可以針對使用虛擬實境對人眼臨床病理知相關影響做更進一步的探討，以避免使用者在使用頭戴式虛擬實境後因相關病徵而導致其在日常生活或工作上有潛在風險。除此之外也可以針對虛擬實境的易感受族群做相關研究探討，以了解易感受族群在使用頭戴式虛擬實境上和使用頭戴式虛擬實境後可能產生之負面健康效應問題。同時建議有將頭戴式虛擬實境裝置納入教育、工作或訓練的各個職場及領域，在使用虛擬實境的使用時間上盡量保持在45分鐘內，避免因過長使用時間對使用者造成視覺負荷的風險，以保障使用者的健康權益。

Head-mounted (HMD) virtual reality device is becoming a common method used in series for education and training in the workplace, educational campus or health industry. The features of high immersion, operability, interaction, and immediate feedback, combined with professional content make HMD become an emerging education and training aid in the workplace or school. However, some adverse effects of using HMD have been reported, including motion sickness, aftereffects and visual fatigue, which were thought to be associated with the designs of hardware or software, use conditions or users’ characteristics. Using HMD might make user discomfort or lead to adverse health effect, which might in turn become barriers for its application. This study was therefore conducted to explore the effects of using head-mounted virtual reality devices at different lengths of time on visual performance like visual acuity, visual cognitive memory, and visual fatigue. Head-mounted display and virtual environment were employed in the present study as hardware. Repeated-measurement design was applied to explore the change of vision and visual performance before and after being exposed to virtual environment. The visual performance test consists of four major aspects: (1) visual sensitivity: examined with visual acuity chart, (2) color vision: measured with color chess, (3) visual cognitive memory performance: measured with the Vienna tracking system, (3) visual fatigue: evaluated with subjective visual fatigue questionnaire. In this study, 30 participants (9 males and 21 females) aged 20–30 years were invited to participate in, excluding those with heart disease, mental illness, or severe eye disease but not those with corrected-to-normal vision. Study subjects were required to take three different time-length virtual reality game experiments of 5 minutes, 20 minutes and 45 minutes, respectively, and accept visual performance tests before and after each experiment. Every study subject participated in the 5 minutes experiment first, then randomly followed by 20-minute and 45-minute experiments or 45-minute and 20-minute experiments as the second and the third experiments. There was at least one week apart between every two consecutive experiments. Results of the visual performance shows that the post-test visual acuity of the left and right eyes of the study subjects were lower than those of pre-test, but there was no statistically significant difference. For the 45-minute experiment group, the post-test average error score of the color chess test was significantly higher than that of the pre-test (p<0.05). Average using time for the color chess test in the post-test was shorter than that of the pre-test (p<0.05). Meanwhile, for the 45-minute experiment group, the post-test average error score of the color chess test was negatively correlated with the Vienna tracking score (p<0.05) and positively with the using time for the Vienna tracking test (p<0.05). The self-reported visual fatigue through questionnaire administration doesn’t show significantly different among all the experiment groups. The findings of this study show that the use of head-mounted virtual reality devices has a negative impact on visual cognitive memory, but no significant effect on visual acuity and visual fatigue. Future research is warranted to further explore the impact of using virtual reality on human eyes from the viewpoint of clinicopathology in order to prevent the potential health risks of eye dysfunction resulting from using head-mounted visual reality in daily life and work. In addition, future research could also be extended to the possible adverse visual performance resulting from using head-mounted virtual reality for the susceptible groups. Meanwhile, it is recommended that the using time for head-mounted virtual reality in education, work, and training should be kept within 45 minutes to avoid the risk of causing adverse effect to the users’ eyes in order to protect the health of users.