Effects Of Extraocular Muscles Involvement On Stereoscopic Vision In Thyroid-associated Ophthalmopathy

Objective:The purpose of this study was to investigate the effects of different degrees of involvement of the extraocular muscles in thyroid-associated ophthalmopathy(TAO)on binocular stereoscopic vision.Methods:This study is a clinical cross-sectional study.A total of 35 TAO patients and a control group of 20 were collected from January 2018 to July 2019 in the department of ophthalmopathy in Peking Union Medical College Hospital.Patients with TAO were divided into groups with limited eye movement(17 cases)and groups without limited eye movement(18 cases)according to the degree of involvement of the extraocular muscles.General ophthalmic examination,contrast-enhanced orbital MRI and synoptophore examination were performed in the three groups.Exophthalmos measurement,total thickness of extraocular rectus(transverse diameter+vertical diameter)were measured on orbital enhancement MRIT2WI.Stereopsis was examined on synoptophore.To analyze the effect of the degree of external ocular muscle involvement on stereoscopic vision and the correlation between the degree of exophthalmos,thickness of extraocular rectus and other factors on stereoscopic vision.Results:There was no significant difference in the presence or absence of grade I simultaneous vision among the three groups.The level II fusion range of the TAO group with limited eye movement was smaller than that of the control group(P<0=.001),while the level II fusion range of the TAO group without limited eye movement was not significantly different from that of the control group(P>0.05).The proportion of grade III stereoscopic blindness in the TAO group with limited eye movement was higher than that in the TAO group without limited eye movement and the control group,respectively,with significant differences(P<0.017,P<0.017).However,there was absence of difference in the proportion of stereoscopic blindness between the TAO group without limited eye movement and the control group(P>0.017).There was no significant difference in stereoscopic quantitative distribution among the three groups(P>0.05).The fusion range of grade II was negatively correlated with the CAS score,the degree of exophthalmos and the sum of the thickness of extraocular rectus muscles.Conclusion:TAO with limited eye movement can affect binocular level II fusion vision and level III stereoscopic vision,but has no significant effect on level I simultaneous vision.TAO has no significant effect on binocular stereoscopic vision without limited eye movement.Level Ⅱconvergence and devision fusion ranges were negatively correlated with the sum of extraocular rectus thickness,respectively.