Experimental Study On Binocular Visual Fields And Reading Speeds Of Four Binocular Hemianopias And Concentric Visual Field Contractions

Objective To investigate the binocular visual fields and binocular reading speeds of four types of binocular hemianopias and concentric visual field contractions.Methods The volunteers were satisfied with two monocular naked visual acuity?0.8,no ophthalmic diseases and dysregulation.The normal vision of volunteers were occluded to simulate different types of visual field defects stipulated in the disability identification standards.Binasal,bitemporal,left and right congruous hemianopsias were simulated in experiment?1?,binocular?2.5°?5°?,binocular?10°?30°?,monocular?2.5°?5°?and monocular?10°?30°?were simulated in experiment?2?.Monocular visual field,binocular visual field and binocular reading speed were measured in each group.Results Experiment?1?The binocular visual field of control group was 104.80%±2.33%.Compared with the control group,the binocular visual field in the left congruous,right congruous and bitemporal hemianopia groups was significantly reduced?P<0.05?,it was54.15%±1.39%,54.65%±1.50%and 81.05%±3.02%,respectively,while that in the binasal hemianopia group was 104.20%±1.91%,which did not decrease significantly?P=0.198?.The reading speed of control group was 443±117 words/min.Compared with the control group,the reading speeds of right congruous,left congruous,bitemporal and binasal hemianopia groups were significantly slower?P<0.05?,which were316±75words/min,372±99 words/min,401±109 words/min and 413±104 words/min,respectively.The regression equation between binocular visual field?Xbinocular?,better eye visual field?Xbetter?and reading speed?Yreading?was:Yreading=1.556Xbinocular+0.291Xbetter+245.109(P of X_binocularinocular regression coefficient<0.001,P of X_betteretter regression coefficient=0.055,QIC=141.947).Experiment?2?The binocular visual field of control group was107.90%±2.59%.Compared to the control group,the binocular visual field of binocular?2.5°?5°?,binocular?10°?30°?,monocular?2.5°?5°?and monocular?10°?30°?groups were significantly smaller?P<0.05?,which were 7.75%±1.07%,31.60%±3.93%,97.55%±2.33%and 97.10%±2.02%,respectively.The reading speed of control group was546±106 words/min.Compared with the control group,only binocular?2.5°?5°?decreased significantly?P<0.05?,which was 408±91 words/min.There were no significant differences between binocular?10°?30°?,monocular?2.5°?5°?and monocular?10°?30°?group?P>0.05?,which were 557±111 words/min,560±120 words/min,and 547±119words/min,respectively.The regression equation between better eye?Xbetter?,worse eye(X_worse)and reading speed(Y_reading)was:Y_reading=0.988X_better+0.114X_worse+446.622(P of X_betteretter regression coefficient<0.001,P of X_worseorse regression coefficient=0.427,QIC=116.991).The regression equation between binocular visual field(X_binocular),worse eye?Xworse?and reading speed?Yreading?was:Yreading=1.066Xbinocular+0.024Xworse+449.891(P of X_binocularinocular regression coefficient<0.001,P of X_worseorse regression coefficient=0.866,QIC=117.392).Conclusion?1?The binocular visual field loss and reading performance are seriously damaged in homonymous hemianopsia,but the damage of binocular visual field is not obvious and has little effect on reading in binasal hemianopsia.When unilateral visual field shrinks,the binocular visual field does not shrink synchronously with the worse eye visual field,and the effect on reading is not obvious.When visual field shrinks in both eyes,it significantly affects reading only when the binocular field of vision is narrowed to near the center.?2?Compared with two monocular visual fields,the relationship between binocular vision and reading speed is more closely and more stable.It is recommended that the binocular vision should be considered in forensic identification of visual field defects.It is necessary to investigate the influence of visual field impairment on person functions,and the forensic evaluation of visual field defects should be established on this basis.