Exotropic Drift And Binocular Alignment After Surgery For Intermittent Exotropia In Children

Objective Intermittent exotropia is the most common type of Exotropia in children. Intermittent exotropia affect the appearance and binocular vision of children.The intermittent exotropia process of most of children is progressive,deviation is intermittent in the early stage of the disease,but over time,intermittent exotropia will eventually lead to the occurrence of the constant exotropia,and even more serious is children’s binocular vision completely losing.At present,surgical operation is the main treatment method of intermittent exotropia.But the long term surgical effects is not satisfactory,the rate of mesoropter at1year after surgery is only40%～83%,and with time goes on,a large portion of children appear exotropia drift which will cause eye position rollback.So surgical treatment of intermittent exotropia is still a challenge.The study aims to explore the long term binocular alignment and exotropic drift within1year after surgical treatment of children’s intermittent exotropia.Methods The study was retrospective case series,which included120cases with intermittent exotropia (aged2～15years) and treated with surgery in Shandong provincial hospital in October2009to November2011.Prism with alternative covering method was used to preoperatively measure the strabismus degree,all cases covered one eye for1hour before measure,and underwent eye movement examination,anterior segment and fundus examination.Based on the strabismus degree and gaze preference (alternating attention or a dominant eye),66cases underwent bilateral lateral rectus recession,the others underwent lateral rectus recession with medical rectus excision,all the surgicaloperations were completed by the same doctor. With postoperative1～3 days.6weeks and1year follow-up. we assess the early and long term surgical effects.Curative effect evaluation standard was as follows:the deviation≤8PD,>+8PD,and>-8PDin primary position was normotropia,undercorrection\recurrence, overcorrection respectively.Results During the follow-up periods of1to3days、6weeks、lyear, the normotropia rate of group A was62.1%,69.7%,62.1%, and that of group B was72.2%、88.9%,70.4%, respectively; the overcorrection rate of group A was21.2%、3%,4.6%, and that of group B was24.1%,1.8%,1.8%, respectively; the undercorrection rate of group A was16.7%、27.3%,33.3%, and that of group B was3.7%、9.3%、27.8%, respectively. There were no significant difference in the normotropia rates (.P=0.243) and overcorrection rates (.P=0.709) between group A and group B, and the difference of the undercorrection rates between the two groups had statistical significant (P=0.023) at postopeative1to3days. There were no significant difference in the normotropia rates (P=0.343), overcorrection rates (P=0.413) and undercorrection rates (P=0.512) between the two groups at postopeative one year. There were no relationships of the following covariables to exotropic drift:age at initial surgery, initial refractive error, corrected vision. angle of strabismus before surgery, whether with oblique muscle surgery simultaneouslyConclusions There was no significant difference in the early and long term normotropia rate between bilateral lateral rectus recession and lateral rectus recession with medical rectus excision.overcorrection rate at postoperative1-3days was significantly decreased within6weeks after surgery.As postoperative time goes on. the undercorrection\recurrence rate gradually increased,that indicated that the eye position of cases with intermittent exotropia showed the trends of the external oblique drift.