The Evaluation Of Cerebral Visual Functions In Low Myopic Adolescence

AIM:Our study aimed to explore whether low myopia would affect the cerebral visual functions by comparing the cerebral visual functions between low myopic and normal individuals.METHODS:120 adolescence matched in ages and genders participated in our study.Subjects were divided into three groups according to their refractive states.Low myopia without anisometropia were in non-anisometropia group,while low myopia with anisometropia were in anisometropia group and normal individuals were divided into control group.The cerebral visual functions tested in our study included perceptual eye position(PEP)、 fixation stability and stereoacuity.In our study,stereoacuity tests can be categorized into two parts.The first part is 3D random-dot test for zero-order stereoacuity(hereinafter as zero-order test)at different viewing distances.The second part are classical stereoacuity tests including Titmus and synoptophore stereoacuity tests.Results:(1)The horizontal PEP bias pixels(the deviation of horizontal PEP)were as follows: 18.9±16.8 pixels in the non-anisometropia group,25.6±22.7 pixels in the anisometropia group,and 3.6 ±3.3pixels in control group.The vertical PEP bias pixels(the deviation of vertical PEP)were as follows:2.9±2.5 pixels in the non-anisometropia group,5.6±6.6 pixels in the anisometropia group,and 2.1±1.2 pixels in control group.One way ANOVA revealed that horizontal PEP bias pixels were much larger in non-anisometropia and anisometropia group,when compared to control group(P<0.05);differences of vertical PEP bias pixels between anisometropia group and control group was significant(P<0.05).(2)Percentage of normal individuals among each group were calculated for further analyze.The results of fixation stability test were respectively 70.0% in non-anisometropia group,35.7% in anisometropia group and 90.0% in control group.test showed that non-anisometropia and anisometropia group had more trouble holding their fixation stable(P<0.05).(3)The results of Titmus stereoacuity test were respectively 86.3% in non-anisometropia group,60.7% in anisometropia group and 89.3% in control group.The results for zero-order test at 0.8m were as following: 93.3% in non-anisometropia group,78.6% in anisometropia group and 96.7% in control group.The results for zero-order test at 1.5m were as following: 46.7% in non-anisometropia group,35.7% in anisometropia group and 69.0% in control group.The results for synoptophore stereoacuity test were as following: 85% in non-anisometropia group,75.9% in anisometropia group and 96.7% in control group.Moreover,anisometropia group behaved much worse in Titmus stereoacuity test(P=0.029)、zero-order test at 0.8m(P=0.048)and synoptophore stereoacuity test(P =0.017)than other two groups.And in zero-order test at 1.5m,both non-anisometropia and anisometropia had much worse stereoacuity than control group(P<0.05).(4)The correlation between fixation stability and Titmus stereoacuity was weak and positive;the correlation between fixation stability and zero-order test was also weak and positive(P<0.05).Conclusions:1.Low myopic adolescence still have certain defects in cerebral visual functions,which includes PEP、fixation stability and zero-order test at 1.5m,even after corrected to their best visual acuity;2.So far,local retinal environment has been the focus of the development in myopia.Our results suggested that researchers might pay more attention on visual cortex in studying the mechanisms of myopia in the near future.