Color-discrimination threshold determination using pseudoisochromatic test plates.

Kaiva Jurasevska,Maris Ozolinsh,Ausma Gutmane,Anete Pausus,Sergejs Fomins,Varis Karitans,Brigita Zutere

doi:10.3389/fpsyg.2014.01376

Abstract

We produced a set of pseudoisochromatic plates for determining individual color-difference thresholds to assess test performance and test properties, and analyzed the results. We report a high test validity and classification ability for the deficiency type and severity level [comparable to that of the fourth edition of the Hardy–Rand–Rittler (HRR) test]. We discuss changes of the acceptable chromatic shifts from the protan and deutan confusion lines along the CIE xy diagram, and the high correlation of individual color-difference thresholds and the red–green discrimination index. Color vision was tested using an Oculus HMC anomaloscope, a Farnsworth D15, and an HRR test on 273 schoolchildren, and 57 other subjects with previously diagnosed red–green color-vision deficiency.

Highlights

Pseudoisochromatic (PIC) test plates are widely used for colorvision screening, congenital deficiency classification, and grading
SPECIFICITY AND SENSITIVITY OF KAMS The ability of the KAMS test to diagnose red–green color-vision deficiency was calculated based on data acquired in the population study
We compared the ability of the KAMS test to grade the severity of the deficiency with that of the HRR test

Summary

Introduction

Pseudoisochromatic (PIC) test plates are widely used for colorvision screening, congenital deficiency classification, and grading. Regardless of the design used in the creation of the PIC tests, they produce different grouping responses in people with normal trichromatic vision and abnormal color vision. It is possible to obtain PIC tests with high performance (sensitivity and specificity approaching values of 1.00) by carefully choosing colored symbol chromatic values (Cole et al, 2006; Cole, 2007). PIC tests usually classify color-vision deficiency into three groups in terms of severity: mild, medium (moderate), and strong (severe). The total color difference ( E∗ab) of the plate stimuli determines the level of difficulty of the plate. For red–green color-vision deficiencies, the advisable values of E∗ab measured according to the Commission internationale de l’eclairage (CIE) LAB formula are as follows:

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