The conventional stimulus for standard automated perimetry is fixed in size, giving elevated contrast thresholds and reduced test reliability in the periphery. Here, we test the hypothesis that appropriate scaling of the size of perimetric stimuli will return fixed thresholds and reduced variability across the visual field. We derived frequency-of-seeing (FOS) curves in five healthy subjects at central (3 degrees) and peripheral (27 degrees) locations with a method of constant stimuli (MOCS) using a desktop LCD display. FOS curves for a Goldmann III (GIII) stimulus were compared with those for size scaled spots. To consider clinical translation, we tested a further five healthy subjects (22-24 years) with the Melbourne Rapid Fields (MRF) tablet perimeter at several locations spanning 1 degree to 25 degrees from fixation, deriving FOS curves (MOCS) and also conducting repeated adaptive clinical thresholding to assess intra- and interobserver variability. We found that GIII contrast thresholds were significantly elevated in the periphery compared with the parafovea, with concomitant reduction of FOS slope. Using appropriately size scaled spots, threshold and slope differences between these locations were significantly reduced. FOS data collected with the tablet perimeter confirmed that size scaling confers broad equivalence of the shape of the FOS curve across the visual field. Repeated adaptive thresholding with size scaled stimuli gave relatively constant intra-observer variability across the visual field, which compares favorably with published normative data obtained with the GIII stimulus. The reduced variability will improve signal-to-noise ratio for correct classification of normal visual field test results, whereas the lower contrast thresholds yield greater dynamic range, which should improve the ability to reliably monitor moderate defects.

中文翻译：

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缩放周边刺激的大小可减少可变性并在整个视野中返回恒定阈值。

标准自动视野测量的常规刺激大小是固定的，从而提高了对比度阈值并降低了周边的测试可靠性。在这里，我们检验了这样一个假设，即适当缩放周边刺激的大小将返回固定阈值并减少整个视野的可变性。我们使用桌面 LCD 显示器采用恒定刺激 (MOCS) 方法，在中心 (3 度) 和外围 (27 度) 位置的五名健康受试者中得出了看到频率 (FOS) 曲线。将 Goldmann III (GIII) 刺激的 FOS 曲线与尺寸标定点的曲线进行比较。为了考虑临床转化，我们用墨尔本快速场 (MRF) 平板电脑周边测试了另外 5 名健康受试者（22-24 岁），在从固定角度跨越 1 度到 25 度的几个位置，导出 FOS 曲线 (MOCS) 并进行重复的自适应临床阈值评估以评估观察者内部和观察者间的变异性。我们发现，与旁中央凹相比，外围的 GIII 对比度阈值显着升高，同时 FOS 斜率降低。使用适当大小的点，这些位置之间的阈值和斜率差异显着减少。使用平板电脑周边收集的 FOS 数据证实，尺寸缩放使 FOS 曲线的形状在视野范围内具有广泛等效性。具有大小比例刺激的重复自适应阈值在整个视野中提供了相对恒定的观察者内变异性，这与使用 GIII 刺激获得的已发布规范数据相比是有利的。