| Objective To explore the relationship between the negative afterimage duration and myopia level,velocity of pursuit eye movement,object's color and the contrast of object and background.Methods 1.Several students were tested by using computer optometry,phoropter and color chart.And 49 of them,including 24 boys and 36 girls with average of 21.12±2.09 years old,ranging from 18 to 26 years old were recruited into this study,the criteria were:(1)Corrected-to-normal vision could reach to 1.0.(2)AN were less than 2.00 D.(3)Three levels of visual function was normal.(4)Color vision was normal.And these subjects were divided into three subgroups in accordance with their SE:(1)Low myopia group(-3.00D?SE?-0.25D),17 cases.(2)Medium myopia group(-6.00D?SE<-3.00D),21 cases.(3)High myopia group(SE<-6.00D),11 cases.In the same level of myopia,the difference of duration were compared between the group of diopter of the dominant eye was higher than non-dominant eye and the lower group.2.Subjects' refractive errors were corrected by frame glasses.3.In order to produce negative afterimage,subjects were asked to stare at different groups of objects.The first group was a yellow static object.The second group was a group of dynamic objects moving horizontally.The shape,color and background of these objects were the same as that in group one,but their velocities were different from each other.The third group was a group of black,static objects,but the contrasts between objects and their backgrounds were different from each other.4.Recording the durations of the negative afterimages induced by the different myopia level,velocity of pursuit eye movement,object's color and the contrast of object and background.5.All data were processed by SPSS 19.0 statistic software.Independent sample t test,Single factor analysis of variance and SNK-q were used to analysis.When P value was less than 0.05,it was considered as having statistic significant.Results1.The difference of negative afterimage durations in three myopia level with the first group of objects had statistic significant(F=23.523,P=0.000).2.The difference of negative afterimage durations between female group and male group had not statistic significant(low myopia group: t=0.358,P=0.724;medium myopia group: t=-1.339,P=0.195;high myopia group: t=-0.781,P=0.457).3.No statistic significant existed between the group of diopter of dominant eye was higher than non-dominant eye and the lower group with the same level of myopia(low myopia group: t=-0.660,P=0.518;medium myopia group: t=-1.433,P=0.164;high myopia group: t=-0.173,P=0.868).4.With the change of object's velocity,the difference of negative afterimage duration had not statistic significant(low myopia group: F=0.321,P=0.925;medium myopia group,F=1.836,P=0.096;high myopia group F=0.384,P=0.887).5.The difference of durations of negative afterimage induced by yellow and black object had not statistic significant(t=0.234,P=0.820).6.The durations of negative afterimage induced by black object in a white background was significant higher than that in a gray background(t=3.548,P=0.001).Conclusions 1.After refractive errors were corrected,it enables people's visual acuity reach to the same level.However,in different myopia level,durations of negative afterimages induced by same object were not the same.And the duration is longer in higher myopia level.And the gender had no effect on the duration of negative afterimage.2.The diopter of dominant eye was higher or not than non-dominant eye has no impact on negative afterimage duration.3.The velocity of pursuit eye movement had no effect on the duration of the negative afterimage within the range of people were able to do pursuit eye movemen.4.When the background becomes dimmer,the negative afterimage duration tends to be shorter.And in a white background,the duration of negative afterimage that induced by yellow object is similar to that induced by black object. |
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