Objective: To investigate the influence of blue light from visual display terminals (VDTs) on human ocular surface. Methods: Prospective intervention test Thirty volunteers were recruited to watch videos on the same VDT in a dark environment, about 40 cm from the screen. Volunteers were supposed to watch videos in the night shift mode that reduces the amount of blue light for 1 hour. At the same time of the second day, they watched the same videos on the VDT in the normal mode for 1 hour. Tear film break-up time (BUT), corneal fluorescein staining scores, lipid layer thickness (LLT), times of blinking in 19.1 seconds and the ratio of partial blinking in 19.1 seconds were measured before and after each watching. Meanwhile, volunteers were asked to complete a questionnaire about their subjective experience after watching. Results: BUT, corneal fluorescein staining scores and LLT showed no significant decreases in the volunteers after they watched videos on the VDT in the night shift mode [BUT before watching: (8.08±3.15)s, BUT after watching in the night shift mode: (5.31±2.49)s, t=-0.52, P>0.05], but there were significant decreases after they watched videos in the normal mode [BUT after watching in the normal mode: (3.35±1.95) s, t=2.40, P<0.05]. At the same time, there was a significant difference between night shift mode and normal mode[BUT after watching in the night shift mode (5.31±2.49)s, BUT after watching in the normal mode: (3.35±1.95)s, t=3.67, P<0.05). Times of blinking and the ratio of partial blinking in 19.1 seconds were increased modestly after watching in 2 different modes, but there was no significant difference(times of blinking after watching in the night shift mode were 5.55±3.27, times of blinking after watching in the normal mode were 5.93±3.59, t=-0.92, P>0.05). The questionnaire results showed that 70.0%(21) of the volunteers reported mild discomfort including eye dryness, itching, pain, foreign body sensation, redness and asthenopia, 46.7%(14) reported no difference between the 2 modes, 36.7%(11) preferred the night shift mode, 16.6%(5) felt better with the normal mode, and 80.0%(24) would like to try the night shift mode in their daily life. Conclusions: Use of VDTs for a short period of time can lower the stability of tear film. The night shift mode may cause less damage to the ocular surface than the normal mode. High-energy blue light from VDTs can be a risk factor in the ocular surface damage, but the damage is reversible. (Chin J Ophthalmol, 2018, 54: 426-431).
目的： 探讨视频显示终端的蓝光对泪膜稳定性的影响。 方法： 前瞻性干预试验选取在校大学生30名，其中男性4名，女性26名，年龄（24.1±1.4）岁。受试者在暗环境中使用同一视频显示终端（iPad）观看视频，距离显示屏约40 cm。受试者先在夜览模式（低蓝光）下观看视频1 h，再于第二天同一时间在相同环境下再在普通模式下观看视频1 h。两次观看视频前后均检查泪膜破裂时间、荧光素钠染色评分、泪膜脂质层厚度（最大值、最小值以及平均值）、19.1 s瞬目次数、19.1 s不完全瞬目所占比，并在试验结束后完成观影感受调查问卷。各项测量数据资料采用配对t检验进行统计学比较。 结果： 受试者观看视频前、夜览模式观看后及普通模式下观看后泪膜破裂时间分别为（8.08±3.15）、（5.31±2.49）、（3.35±1.95）s，角膜荧光素钠染色评分分别为（0.33±0.57）、（0.55±0.62）、（0.78±0.59）分，泪膜脂质层厚度分别为（69.57±21.27）、（70.80±20.38）、（62.55±16.89）nm。泪膜破裂时间、荧光素钠染色评分和泪膜脂质层厚度平均值在夜览模式观看前后差异无统计学意义（t=-0.52，P>0.05），正常模式观看前后差异有统计学意义（t=2.40，P<0.05），正常模式与夜览模式观看后差异有统计学意义（t=3.67，P<0.05）。瞬目次数及不完全瞬目所占比在观看视频后略有增加但无统计学差异（t=-0.71，P>0.05）。调查问卷结果显示：21名受试者（70.0%）在观看夜览模式和普通模式视频后均出现轻微眼睛干涩、疼痛、异物感、视疲劳等不适；14名受试者（46.7%）的感受差别不大，11名受试者（36.7%）表示夜览模式更舒适，另外5名受试者（16.6%）表示普通观影模式更舒适；24名受试者（80.0%）愿意以后尝试采用夜览模式。 结论： 短时间观看显示屏即会造成泪膜稳定性降低。显示屏中的蓝光所含能量高，对眼表刺激较大，iPad的夜览模式（低蓝光）对眼表泪膜稳定性的破坏小于普通模式。短时间暴露在视频显示终端蓝光下即可造成眼表一定程度的损伤，但这种损伤可逆。（中华眼科杂志，2018，54：426-431）.
Keywords: Computer terminals; Eye manifes tations; Light; Photic stimulation; Tears.