摘要目的 探讨不同类型视觉显示终端(VDT)引起视疲劳的差异.方法 对照研究.纳入在校大学生共68人作为受试者,男性21人,女性47人,年龄(21±2)岁.采用数字表法将受试者随机分为电视组和投影组,每组34人,分别观看液晶电视和投影仪播放的视频,其中投影组先后观看投影仪投至金属幕与玻璃微珠幕的视频.所有受试者在相同环境下观看视频60 min,观看前后分别填写视疲劳量表,测量视功能参数,并记录瞬目情况.观看视频前后各项观察指标及组间数据的比较根据数据正态性选择t检验或秩和检验进行统计学分析.结果 所有受试者观看视频后均出现视疲劳量表分值增加、瞬目频率加快、闪光融合频率降低、集合近点远移、负相对调节能力下降.观看前投影组(金属幕和玻璃微珠幕)和电视组受试者视疲劳量表分值分别为1.0(1.2)、1.3(1.6)、0.5(0.9)分,观看后分别为2.1(1.9)、2.1(1.7)、1.2(1.0)分,差异有统计学意义(Z=-4.72,-4.83,-3.75;P＜0.05);各组受试者的瞬目频率分别为11.5(10.6)、15.3(11.9)及7.0(13.0)次/min,观看视频后分别为15.0(13.0)、17.0(16.0)及15.0(12.0)次/min,差异有统计学意义(Z=-2.64,-2.38,-4.12;P＜0.05);观看视频前各组平均闪光融合频率分别为(35.76±2.98)、(35.84±2.79)及(35.44±2.21)Hz,观看视频后分别为(35.09±2.78)、(34.94±2.67)及(34.57±2.33)Hz,差异有统计学意义(t=2.07,2.63,3.39;P＜0.05);观看视频前各组集合近点分别为3.9(2.6)、4.0(2.5)及4.3(2.7)cm,观看视频后分别为5.4(3.8)、4.8(2.7)及6.1(3.9)cm,差异有统计学意义(Z=-3.39,-2.27,-3.36;P＜0.05);观看前各组负相对调节值分别为2.00(0.50)、2.00(0.56)及2.00(0.25)D,观看后为1.75(0.50)、1.75(0.25)及1.75(0.50)D,较观看前差异有统计学意义(Z=-1.98,-2.09,-2.53;P＜0.05).观看视频前后各组受试者正相对调节、调节幅度、调节反应和负融像性参数在各组中均未发现明显改变.投影组受试者(金属幕和玻璃微珠幕)在观看视频后表现出更明显的主观视疲劳症状,与电视组相比差异有统计学意义(Z=-2.09,-2.21;P＜0.05);而投影组不同幕布之间各指标差异无统计学意义(P＞0.05).此外,投影组受试者在观看金属幕和玻璃微珠幕后分别出现了正融像性集合参数恢复值与破裂值下降,而电视组受试者观看视频前后未发现正融像性集合参数的改变.结论 短时间、较远距离通过VDT观看视频可引起明显的视疲劳症状.视疲劳的产生可能与正融像性集合能力的下降有关;观看投影比观看液晶电视显示更容易引起视疲劳;投影采用金属幕或玻璃微珠幕对人眼的影响无明显差异.

abstractsObjective To explore the effect of different types of visual display terminals (VDT)on visual fatigue.Methods A total of 68 subjects were enrolled and divided into flat screen group,metal screen group and glass bead screen group.The subjects watched a video in the same environment for 60 minutes.Before and after watching,they were asked to fill in a visual fatigue rating scale and underwent visual function examinations.The blink rate of subjects was recorded during the experiment.Results After watching the video,for the metal screen,glass bead screen,and fiat screen group respectively:(1)The median (interquartile range,IQR) of visual fatigue rating increased significantly (before:1.0 (1.2),1.3 (1.6),0.5 (0.9);after:2.1 (1.9),2.1 (1.7),1.2 (1.0);Z=-4.72,-4.83,-3.75;all P＜0.05).(2) The median (IQR) of blink frequency increased significantly (before:11.5 (10.6),15.3 (11.9),7.0 (13.0) times/minute;after:15.0 (13.0),17.0 (16.0),15.0 (1 2.0) times/minute;Z=-2.64,-2.74,-4.12;all P＜0.05).(3) The mean (± standard deviation) of critical flicker fusion frequency (CFF) decreased significantly [before:(35.76±2.98),(35.84±2.79),(35.44±2.21) Hz;after:(35.09±2.78),(34.94±2.67),(34.57±2.33) Hz;t=-2.64,-2.38,-4.12;all P＜0.05).(4)The median (IQR) of near point of convergence (NPC) became significantly larger [before:3.9 (2.6),4.0 (2.5),4.3 (2.7) cm;after 5.4 (3.8),4.8 (2.7),6.1 (3.9) cm;Z=-3.39,-2.27,-3.36;all P＜0.05].(5)The median of negative relative accommodation (NRA) reduced significantly [before:2.00 (0.50),2.00 (0.56),2.00 (0.25) cm;after 1.75 (0.50),1.75 (0.25),1.75 (0.50) cm;Z=-1.98,-2.09,-2.53;all P＜0.05].Meanwhile,no significant changes were found for the positive relative accommodation (PRA),accommodative amplitude,accommodative response,negative relative vergence in all groups after watching the video.The comparisons between the three groups showed that,after watching the video,the participants in the two kinds of projection screen group (the metal and glass bead screen group) had more subjective visual fatigue than those in the fiat screen group respectively (Z=-2.09,-2.21;all P＜0.05),while there was no significant difference in subjective visual fatigue between the two projection screen groups (P＞0.05).In addition,positive fusional vergence recovery point and break point decreased after watching the video in the metal screen and glass bead screen group,respectively (t=4.15,2.07;all P＜0.05).However,no such change was found in the fiat screen group.Conclusions Short-term and long-distance VDT operations have significant effects on visual fatigue,which may be due to the decreased positive convergence ability.VDT operations over projection screens may result in more visual fatigue than LED flat panel display,while the effect of different projection screen types have insignificant influences on visual fatigue.