Maguire L J, Bourne W M
Department of Ophthalmology, Mayo Foundation, Rochester, Minnesota.
Am J Ophthalmol. 1989 Apr 15;107(4):323-30. doi: 10.1016/0002-9394(89)90653-3.
We used a topography system to evaluate retrospectively the pattern of power distribution seen preoperatively and postoperatively in six patients with high postkeratoplasty astigmatism. The relaxing incisions had all been placed based on visual inspection of keratoscope mires alone. Computer analysis of keratoscope photographs showed considerable individual variation in the degree of surface irregularity in preoperative topography. Our data suggest that the steep axis of the postkeratoplasty graft is better conceptualized as two steep hemimeridians. These hemimeridians were separated by an angle other than 180 degrees (two of six cases), and often showed fairly large changes in power from the most central to peripheral areas of the graft analyzed (three of six cases). Asymmetry of power between the two steep hemimeridians was seen in all cases. Areas of maximum steepening were often present in the peripheral portions of the graft in areas other than the major hemimeridians. Individual variation in preoperative corneal irregularity and asymmetry appeared to have an effect on the success of the relaxing incisions.
我们使用一种地形图系统，对6例角膜移植术后高度散光患者术前和术后的屈光力分布模式进行回顾性评估。所有松解切口均仅基于角膜镜影像的目视检查来确定位置。对角膜镜照片进行计算机分析显示，术前地形图中表面不规则程度存在相当大的个体差异。我们的数据表明，角膜移植术后植片的陡峭轴更好地理解为两个陡峭的半子午线。这些半子午线被非180度的角度分开（6例中有2例），并且在分析的植片从最中心到周边区域的屈光力通常有相当大的变化（6例中有3例）。所有病例中均可见两个陡峭半子午线之间屈光力不对称。最大变陡区域通常出现在植片周边部分而非主要半子午线所在区域。术前角膜不规则和不对称的个体差异似乎对松解切口的成功率有影响。
