The Effect Of Monocular Vision Decline On Binocular Visual Function

Objective To explore the relationships between binocular visual function and the decline of monocular vision acuity,and to explore the combined use of various testing methods in evaluating binocular vision function.Methods The different visual acuity(VA)of each one’s dominant eye has been induced by placing the lenses in front of the dominant eyes and the induced VA was divided into four groups: the VAs of two eyes are greater than 0.8 separately(group A);the VA of one eye is better than 0.3 but worse than 0.5,the VA of other eyes are greater than 0.8(group B-monocular mild loss);the VA of one eye is better than 0.1 but worse than 0.3,the VA of other eyes are greater than 0.8(group Cmonocular moderate loss);the VA of one eye is better than 0.05 but worse than 0.1,the VA of other eyes are greater than 0.8(group D-monocular severe loss).The visual acuity,contrast sensitivity,VEP P100 peak amplitude,latency and stereopsis acuity of left eye,right eye and binocular eye were measured,and the BSR and VEPBS were calculated.Results(1)Central visual acuity: With the decrease of VA of the monocular,the VA of the binocular decreased to a certain extent.The binocular visual acuity of group B was 4% lower than that in group A(P>0.05).The binocular visual acuity of group C was 17% lower than that in group A(P<0.05),and in group D,the binocular visual acuity of group decreased by 21%(P<0.05).(2)Contrast sensitivity:(1)At the spatial frequency of 1.5cpd,the binocular CS of group C decreased by 17% compared with the group A(P<0.05),the binocular CS of group D decreased by 23% compared with the group A(P<0.05);At the spatial frequency of 3.0cpd,the binocular CS of group C decreased by 30% compared with the group A(P<0.05),the binocular CS of group D decreased by 26% compared withthe group A(P<0.05);At the spatial frequency of 6.0cpd,the binocular CS of group C decreased by 22% compared with the group A(P<0.05),the binocular CS of group D decreased by 29% compared with the group A(P<0.05);At the spatial frequency of12.0cpd,there were no significant differences about binocular CS between any groups;At the spatial frequency of 18.0cpd,the binocular CS of group C decreased by21% compared with the group A(P<0.05),the binocular CS of group D decreased by27% compared with the group A(P<0.05);There was a significant positive correlation between the visual acuity of the monocular and the binocular CS(P<0.05).(2)The BSRs of group A and group B were better than 1 at all frequencies.In group C,BSR was worse than 1 at 18.0cpd space frequency,and in group D,BSR was worse than 1at 3.0cpd,6.0cpd,12.0cpd,18.0cpd spatial frequency.(3)P-VEP:(1)Under the stimulation of 6’ angle,the amplitude of P100 peak in group B decreased by 9.81% compared with group A(P<0.05).The amplitude of P100 peak in group C decreased by 27.41% compared with group A(P<0.05),and the amplitude of binocular P100 peak in group D decreased by 35.48% compared with group A(P<0.05).There was a significant positive correlation between the amplitude of P100 peak and the VA of monocular(P<0.05).(2)There was no significant difference in the latency of P100 peak in each group(P>0.05).(3)VEPBS in group A was greater than that in group B,and VEPBS in group B was larger than that in group C,and VEPBS in group C was larger than that in group D(P<0.05).(4)Stereopsis:With the increase of visual acuity in monocular,the stereoacuity threshold of binocular recognition increased and the stereoscopic visual acuity decreased.The stereopsis acuity threshold of group B increased by 1.44 times than that of group A,and the stereopsis acuity threshold of group C increased by 1.53 times compared with group A,and the stereopsis acuity threshold of group D increased by 2.17 times than that of A group(P< 0.05).(5)There was a significant negative correlation between stereopsis and binocular vision,binocular CS and binocular VEP amplitude(P<0.05).Conclusions With the decrease of monocular vision,the impairment ofvisual function become more serious,specially at higher spatial frequencies.The CS value of the binocular and the amplitude of the P100 peak under 6 ’stimulus could be used to speculate on the degree of vision decline in monocular.Stereopsis is highly correlated with binocular contrast sensitivity and binocular VEP amplitude,It can be used for evaluating and predicting binocular vision function.It is worth further research.