模拟单眼视对视觉拥挤效应的影响

Effect of Simulated Monovision on Crowding

目的:建立单眼视的模拟方法及周边视觉拥挤效应的测量方法,并利用该方法评估模拟单眼视下的周边视觉拥挤效应是否较正常情况更严重。方法:实验研究。于2015年3-11月期间选取温州医科大学眼视光学院在校健康学生和教师20例。正常对照时,双眼均给予清晰的视标(模糊度数为0D);模拟单眼视时,左眼给予清晰的视标,右眼给予模糊的视标(模糊度数分别为0.75、1.50、2.50、3.50D,顺序随机)。视觉拥挤效应的目标视标的偏心度(Ecc)为2.5°、5.0°、7.5°(顺序随机),阈值测量方法为心理物理学的阶梯法。通过比较模拟单眼视状态与正常对照状态的视觉拥挤效应的特征和差异,评估模拟单眼视对视觉拥挤效应的影响。不同模糊度数及不同Ecc时视觉拥挤效应的比较采用双因素重复测量方差分析,组间两两比较采用Bonferroni矫正过的t检验。结果:视觉拥挤效应显著依赖于模糊度数(F=13.37,P<0.001)和Ecc(F=296.90,P<0.001)。模糊度数与Ecc的交互作用显著(F=4.03,P<0.001)。当Ecc分别为7.5°、5.0°时,不同模糊度数下测得的视觉拥挤效应差异均有统计学意义(F=8.59,P<0.001;F=3.74,P=0.01),模糊度数越大,视觉拥挤效应越重。当Ecc为2.5°时,不同模糊度数下测得的视觉拥挤效应差异均无统计学意义(F=1.13,P=0.34)。结论:相比于正常对照情况,模拟单眼视下的视觉拥挤效应加重,并且与模糊眼的模糊度数及目标视标的Ecc相关。

Objective:To test whether crowding is much more severe under simulated monovision conditions.Methods:This was an experimental study.Twenty subjects participated in this experimental study from March to November 2015 in Wenzhou Medical University.Both eyes viewed clear images under normal conditions.While under the simulated monovision condition,one eye viewed a clear image(OD),and the other eye viewed a blurred image(0.75,1.50,2.50,3.50 D).The eccentricities of the target in this study were 2.5°,5.0°,and 7.5°.The threshold of the crowding effect was measured by a staircase method.Two-way ANOVA with repeated measures and a t-test with Bonferroni correction were used to test whether crowding was much more severe under the simulated monovision condition.Results:Crowding depended significantly on intraocular blur(F=13.37,P<0.001)and eccentricity(Ecc)(F=296.90,P<0.001).Significant interactions between intraocular blur and Ecc were found(F=4.03,P<0.001).When the eccentricity was 7.5°or 5.0°,intraocular blur significantly affected the critical gap size of crowding(F=8.59,P<0.001;F=3.74,P=0.01).However,intraocular blur did not affect the critical gap size of crowding when the eccentricity was 2.5°(F=1.13,P=0.34).Conclusions:Crowding is much more severe under simulated monovision conditions than normal conditions,and the difference is dependent on intraocular blur and eccentricity.