Weindler J, Spang S, Ruprecht K W
Universitäts-Augenklinik Homburg (Saar).
Klin Monbl Augenheilkd. 1996 Aug-Sep;209(2-3):105-8. doi: 10.1055/s-2008-1035287.
The standard keratometry measures the central corneal refractive power by only four sample points. there is a risk for poor or incorrect measurements in high irregular postoperative astigmatism following penetrating keratoplasty. Therefore we compared the standard keratometry with the computer assisted corneal topography.
In the study 43 consecutive measurements after penetrating keratoplasty, with an astigmatism > 4 dpt measured with standard keratometry (Zeiss Ophthalmometer), were analyzed. A computer assisted corneal topography (Eye Sys) was performed simultaneously. 22 measurements were received before, 21 measurements after T-incisions. The astigmatism value and axis measured by keratometry and corneal topography were compared and the correlation coefficient were calculated. As a simple index for the asymmetry of the resulting corneal cylinder measured by corneal topography, the frequency and the axis difference of both steep hemimeridians within the 3 mm zone were determined.
The astigmatism values measured by standard keratometry (8.1 +/- 2.7 dpt) were significantly higher than the values measured by the computer assisted corneal topography (6.1 +/- 2.2 dpt). The difference of the cylinder axis measured by standard keratometry and corneal topography was 19 +/- 23 degrees; 10 +/- 15 degrees before and 29 degrees +/- 26 degrees after T-incision. The comparison of the astigmatism values showed a correlation coefficient of 0.82 in the total group, of 0.84 before and of 0.83 after T-incisions. In 26% of all measurements the axis difference of both steep hemimeridians (3-mm zone) was more than 30 degrees. After T-incisions this difference increased.
Based on the results of this study, it seems reliable to identificate patients with high postoperative astigmatism following penetrating keratoplasty by standard keratometry.
标准角膜曲率计仅通过四个采样点测量中央角膜屈光力。穿透性角膜移植术后出现高度不规则散光时，存在测量结果不佳或错误的风险。因此，我们将标准角膜曲率计与计算机辅助角膜地形图进行了比较。
在该研究中，对43例穿透性角膜移植术后连续测量的数据进行了分析，这些测量采用标准角膜曲率计（蔡司角膜曲率计）测量散光度数>4 dpt。同时进行了计算机辅助角膜地形图（Eye Sys）检查。T形切口前进行了22次测量，T形切口后进行了21次测量。比较角膜曲率计和角膜地形图测量的散光值和轴位，并计算相关系数。作为通过角膜地形图测量所得角膜柱镜不对称性的一个简单指标，确定了3 mm区域内两个陡峭半子午线的频率和轴位差异。
标准角膜曲率计测量的散光值（8.1±2.7 dpt）显著高于计算机辅助角膜地形图测量的值（6.1±2.2 dpt）。标准角膜曲率计和角膜地形图测量的柱镜轴位差异为19±23度；T形切口前为10±15度，T形切口后为29±26度。散光值比较显示，总组的相关系数为0.82，T形切口前为0.84，T形切口后为0.83。在所有测量中，26%的两个陡峭半子午线（3 mm区域）的轴位差异超过30度。T形切口后这种差异增加。
基于本研究结果，通过标准角膜曲率计识别穿透性角膜移植术后高度散光患者似乎是可靠的。
