眼球三维空间定位测量法的建立

Establishment of Three Dimensional Imaging System for Measurement of Eyeball Position

目的建立能满足临床需要的眼球三维空间定位测量法,以精确测定眶病患者眼球的位置。方法螺旋CT扫描眶区,层厚1mm;进行三维重建,并以左右外耳道中点、健侧眶下缘和犁骨基底为基点建立三个互相垂直的参考平面:轴向Pa、冠状Pc和矢状Ps,以角膜顶点和眼球中心到参考平面的距离确定眼球的空间位置。选20例眶眼正常患者分别用该法和传统临床方法(Hertel突度计等)对眼球突度、瞳距等进行测量,作配对t检验。结果三维CT测量法和Hertel突度计测量两侧眼球的结果差异无显著性(P>0.05),测量瞳距结果与临床方法差异无显著性(P>0.05)。但三维CT法较Hertel突度计所测绝对突度值偏大[3DCT(13.90±2.40)mm,Hertel(12.4±2.4)mm,P<0.01]。结论本测量法能精确测量正常眼球的三维空间位置,弥补传统检测方法的不足,亦适用于单侧眶颧骨折患者。

Objective To establish a new technique from CT database for 3D measurement of eyeball position. Methods The helical CT images（1 mm section thickness） of orbital region were obtained. 3D visum models were fabricated on three reference planes（axial plane, Pa; coronal plane, Pc and sagittal plane, Ps） which based on the left and right external auditory meatus point, one side of normal orbitale and the basal of nasal septal were collected. The distances between eyeballs and Pa, Pc or Ps were measured for the study. 20 patients without orbital pathological changes were selected in the study. This technique was assessed by comparing the measurements of proptosis and interpupillary distance obtained by physicians and 3D CT. Results The distances obtained by physicians or 3D CT did not show any signficant differences on asymmetry between both eyes（P 〉 0.05）, while there was a significant difference between Hertel exophthalmometry and 3D CT[mean Hertel（12.4±2.4）mm, mean 3D CT（13.90±2.40）mm, P〈0.01]. Conclusion This measurement is accurate and reliance on the 3D eyeball position especially for the application on complex cases with pathological changes on the lateral orbital rim. This method overcome the disadvantages from the traditional method.