Mittelviefhaus K, Bach M, Jedynak A, Kommerell G
Universitäts-Augenklinik Freiburg.
Ophthalmologe. 1993 Apr;90(2):132-5.
Single Landolt Cs were presented in one of four positions on a monitor. Subjects responded by pressing one of four buttons (forced choice). A computer selected the size of the Landolt Cs on a logarithmic scale using the "Best PEST" algorithm (Best Parameter Estimation by Sequential Testing), a modern procedure to measure psychophysical thresholds. For comparison, conventional measurements according to DIN 58220 (Deutsche Industrie Norm) were performed with Landolt Cs projected in eight positions, using three out of five correct responses as the threshold criterion. Examination of 23 patients (most of them with senile cataract) did not show any significant difference between the two tests in either visual acuity or reproducibility on two consecutive days. The coefficients of variation between sessions were 22% for the Freiburg test and 26% for the DIN test and 18% between the two tests, pooled over two sessions. The Freiburg acuity test thus appears to be numerically equivalent to the DIN 58220 procedure. In addition, it has a number of advantages: (1) examiner-dependent variability is reduced; therefore, the test can be used by inexperienced examiners; (2) the forced choice technique is used rigorously; (3) mistakes in confounding oblique directions are largely avoided; (4) the procedure is about twice as fast.
在显示器上以四个位置之一呈现单个兰多尔特C形视标。受试者通过按下四个按钮之一进行响应（强制选择）。计算机使用“最佳PEST”算法（顺序测试最佳参数估计）按对数尺度选择兰多尔特C形视标的大小，这是一种测量心理物理学阈值的现代方法。为作比较，按照DIN 58220（德国工业标准）进行传统测量，将兰多尔特C形视标投射在八个位置，以五次正确响应中的三次作为阈值标准。对23名患者（大多数患有老年性白内障）进行检查发现，在视力或连续两天的可重复性方面，两种测试之间均未显示出任何显著差异。两次测试之间的变异系数，弗赖堡测试为22%，DIN测试为26%，两次测试合并后的变异系数为18%。因此，弗赖堡视力测试在数值上似乎等同于DIN 58220程序。此外，它还有许多优点：（1）减少了检查者相关的变异性；因此，该测试可供经验不足的检查者使用；（2）严格使用强制选择技术；（3）很大程度上避免了混淆倾斜方向的错误；（4）该程序速度约快两倍。
