Schulze Marc M, Hutchings Natalie, Simpson Trefford L
*Dipl Ing(FH)AO †BSc (Hons), MCOptom, PhD ‡DipOptom, MSc, PhD Centre for Contact Lens Research, School of Optometry, University of Waterloo, Ontario, Canada (MMS) and School of Optometry, University of Waterloo, Ontario, Canada (MMS, NH, TLS).
Optom Vis Sci. 2010 Mar;87(3):159-67. doi: 10.1097/OPX.0b013e3181ce07f1.
To use psychophysical scaling to investigate if the inclusion of reference anchors affected the perceived redness of the reference images of four bulbar redness grading scales and to convert grades between scales.
Ten participants were asked to arrange printed copies of the McMonnies/Chapman-Davies (6), IER (4), and Efron (5) grading scale images relative to each other, using the stationary but unlabeled 10, 30, 50, 70, and 90 reference images of the validated bulbar redness scale as additional anchors within a given 0 (minimum) to 100 (maximum) redness range (anchored scaling). The position of each image was averaged across observers to represent its perceived redness within this range. Anchored scaling data were then compared with data from a previous study, where the images of all four grading scales had been scaled for the same experimental setup, but with no reference anchors provided (non-anchored scaling). Averaged perceived redness as determined with anchored scaling was used to cross-calibrate grades between scales.
Overall, perceived redness of the reference images was significantly different within each scale (repeated measures analysis of variance, all scales p < 0.001). There were differences in perceived redness range and when comparing reference levels between scales. Anchored scaling resulted in an apparent shift to lower perceived redness for all but one reference image compared with non-anchored scaling, with the rank order of the 20 images for both procedures remaining fairly constant (Spearman's ρ = 0.99).
The re-scaling of the reference images in the anchored scaling experiment suggests that redness was assessed based on within-scale characteristics and not using absolute redness scores, a mechanism that can be referred to as clinical scale constancy. The perceived redness data allow practitioners to modify the grades of the scale they commonly use for comparison of their grading estimates with grades obtained with another calibrated scale.
运用心理物理学标度法，研究纳入参考锚点是否会影响四种球结膜充血分级量表参考图像的感知充血程度，并实现不同量表之间的分级转换。
让10名参与者将McMonnies/Chapman-Davies（6级）、IER（4级）和Efron（5级）分级量表图像的打印件相互排列，将经过验证的球结膜充血量表中固定但未标记的10、30、50、70和90的参考图像作为额外的锚点，置于给定的0（最小）至100（最大）充血范围内（锚定标度）。对每个图像在观察者之间的位置进行平均，以表示其在此范围内的感知充血程度。然后将锚定标度数据与之前一项研究的数据进行比较，在之前的研究中，所有四个分级量表的图像针对相同的实验设置进行了标度，但未提供参考锚点（非锚定标度）。用锚定标度确定的平均感知充血程度用于跨量表校准分级。
总体而言，每个量表内参考图像的感知充血程度存在显著差异（重复测量方差分析，所有量表p<0.001）。在感知充血范围以及比较不同量表的参考水平时存在差异。与非锚定标度相比，锚定标度导致除一张参考图像外的所有参考图像的感知充血程度明显降低，两种方法中20张图像的排序保持相当稳定（斯皮尔曼ρ=0.99）。
锚定标度实验中参考图像的重新标度表明，充血程度是根据量表内的特征进行评估的，而非使用绝对充血分数，这种机制可称为临床量表恒定性。感知充血数据使从业者能够修改他们常用量表的分级，以便将其分级估计与使用另一种校准量表获得的分级进行比较。
