Rubin A, Harris W F
Department of Optometry, Rand Afrikaans University, Johannesburg, South Africa.
Optom Vis Sci. 1995 Jun;72(6):403-10. doi: 10.1097/00006324-199506000-00008.
The refractive variation of a sample of 106 university students (63 females and 43 males) studying optometry was examined by means of autorefraction. Stereo-pair scatter plots in Euclidean three-dimensional h-space are used to illustrate the nature of the spread or distribution of data measurements found in particular subjects. A wide variety of different distributions were observed ranging from tightly to loosely clustered arrangements of measurements. Some aspects of departure from multivariate normality, including outliers (atypical measurements in a sample) and polymodal or multimodal distributions, are demonstrated. Outliers appear to be possible anywhere in the space of the scatter plots, although outliers may be more common in the region of h-space corresponding to transitory increases in accommodation. Multimodal distributions may be indicative of changes in ocular fixation during autorefraction or may reflect accommodative or other anomalies. Other departures from multivariate normality such as kurtosis and skewness are also of importance when attempting to form an understanding of variation of refractive state. Measurements made on an artificial or test eye showed very tight clusters in h-space. This suggests that the autorefractor itself contributes little to the variation observed during autorefraction of an eye.
对106名视光学专业大学生（63名女性和43名男性）的样本进行了自动验光检查，以检测其屈光变化。欧几里得三维h空间中的立体对散点图用于说明特定受试者数据测量值的分布或离散性质。观察到了各种各样不同的分布，从紧密到松散的测量值聚类排列。展示了偏离多元正态性的一些方面，包括异常值（样本中的非典型测量值）和多峰或多模态分布。异常值似乎可能出现在散点图空间的任何位置，尽管异常值在h空间中与调节暂时增加相对应的区域可能更常见。多模态分布可能表明自动验光期间眼注视的变化，或者可能反映调节或其他异常情况。在试图理解屈光状态变化时，其他偏离多元正态性的情况，如峰度和偏度也很重要。在人工眼或测试眼上进行的测量在h空间中显示出非常紧密的聚类。这表明自动验光仪本身对眼睛自动验光期间观察到的变化贡献很小。
