Gardiner S K, Crabb D P
Faculty of Science and Mathematics, The Nottingham Trent University, Nottingham, UK.
Br J Ophthalmol. 2002 May;86(5):560-4. doi: 10.1136/bjo.86.5.560.
To investigate the effect of frequency of testing on the determination of visual field progression using pointwise linear regression (PLR).
A "virtual eye" was developed to simulate series of sensitivities over time at a given point in the eye. The user can input the actual behaviour of the point (for example, stable or deteriorating steadily), and then a configurable amount of noise is added to produce a realistic series over time. The advantage of this over using patient data is that the actual status of the eye is known. Series were generated using different frequencies of testing, and the diagnosis that would have been made from each series was compared with the true status of the eye. A point was diagnosed as progressing if the regression line for the series showed a deterioration of at least 1 dB per year, significant at the 1% level. From these results, graphs were produced showing the number of points correctly or incorrectly diagnosed as progressing.
With the virtual eye deteriorating at a rate of 2 dB/year, it was found that the point was determined to be progressing quicker when more tests were carried out each year. With a stable virtual eye, it was found that increasing the frequency of testing increased the number of series that were falsely labelled as progressing during the first 3 years of testing.
As the frequency of testing increases, the sensitivity of PLR increases. However, the specificity decreases; possibly meaning more unnecessary changes in treatment. Three tests per year provide a good compromise between sensitivity and specificity.
使用逐点线性回归（PLR）研究检测频率对视野进展判定的影响。
开发了一个“虚拟眼”来模拟眼睛中某一给定位置随时间的一系列敏感度。用户可以输入该位置的实际变化情况（例如，稳定或稳步恶化），然后添加可配置量的噪声以生成随时间变化的真实序列。与使用患者数据相比，这样做的优势在于眼睛的实际状态是已知的。使用不同的检测频率生成序列，并将根据每个序列做出的诊断与眼睛的真实状态进行比较。如果序列的回归线显示每年至少恶化1 dB，且在1%水平上具有显著性，则判定该点进展。根据这些结果，绘制图表展示正确或错误诊断为进展的点数。
当虚拟眼以每年2 dB的速度恶化时，发现每年进行更多检测时，该点被判定进展得更快。对于稳定的虚拟眼，发现在检测的前3年中，增加检测频率会增加被错误标记为进展的序列数量。
随着检测频率的增加，PLR的敏感度增加。然而，特异度降低；这可能意味着更多不必要的治疗变化。每年进行三次检测在敏感度和特异度之间提供了良好的平衡。
