Kushner B J, Fisher M R, Lucchese N J, Morton G V
Department of Ophthalmology, University of Wisconsin, Madison.
J Pediatr Ophthalmol Strabismus. 1994 May-Jun;31(3):138-46; discussion 151-2. doi: 10.3928/0191-3913-19940501-03.
Previous studies have suggested that the location of the equator should be important in determining the site of a "safe maximum recession" of a rectus muscle, and that the location of the equator should be a function of axial length. Exactly where in relationship to the equator a muscle can be safely recessed has never been scientifically determined. Over a 4-year period, we measured axial length on all patients we operated on for strabismus. Using a previously derived formula, we were able to calculate the limbus-to-equator distance, given axial length. Based on our analysis of 28 patients in whom we recessed one or both medial recti posterior to the equator, we believe that recessions of the medial recti up to 1.5 mm posterior to the equator should not produce postoperative medial rectus underaction associated with an overcorrection, but recessions that are further than 1.5 mm posterior to the equator may do so. Recessions to a point greater than 11 mm from the limbus do not appear to be associated with late progressive overcorrection provided that the site of recession is not greater than 1.5 mm posterior to the equator. Using our previously determined formula for estimating the location of the equator, given axial length, we have generated easy-to-use reference tables for determining the location of the equator in terms of millimeters posterior to the limbus. Also, based on axial length data from 180 strabismus patients, we have generated an algorithm for predicting axial length, given age, and refractive error, which may be useful to the strabismus surgeon in predicting the location of the equator when A-scan ultrasonography is not available.
以往的研究表明，赤道的位置在确定直肌“安全最大后徙”部位时应具有重要意义，且赤道的位置应是眼轴长度的函数。但肌肉相对于赤道究竟能安全后徙到何处，从未得到科学确定。在4年的时间里，我们对所有接受斜视手术的患者测量了眼轴长度。利用先前推导的公式，在已知眼轴长度的情况下，我们能够计算出角膜缘至赤道的距离。基于对28例将一条或两条内直肌后徙至赤道后方的患者的分析，我们认为内直肌后徙至赤道后方1.5mm不应导致与过矫相关的术后内直肌功能不足，但后徙超过赤道后方1.5mm可能会导致这种情况。只要后徙部位不超过赤道后方1.5mm，后徙至距角膜缘大于11mm的位置似乎与晚期渐进性过矫无关。利用我们先前确定的在已知眼轴长度时估算赤道位置的公式，我们生成了便于使用的参考表，以根据角膜缘后方的毫米数确定赤道的位置。此外，基于180例斜视患者的眼轴长度数据，我们生成了一种算法，在已知年龄和屈光不正的情况下预测眼轴长度，这在斜视手术医生无法进行A超超声检查时预测赤道位置可能会有所帮助。
