Color vision assessment‐3. An efficient, two‐step, color assessment protocol

Abstract

Color vision tests and multi-test protocols in current use often fail to detect small changes in red/green (RG) and yellow/blue (YB) color vision due to poor sensitivity. The tests also have low specificity. In this study, we examine how improved understanding of within-and inter-subject variability in RG and YB color vision and accurate assessment of the differences in color thresholds between the least-sensitive, age-matched normal trichromats, and the leastaffected deutans and protans can be used to design an efficient color vision screener (CVS) test. To achieve this objective, we examined two extensive data sets from earlier studies and carried out new experiments to provide better estimates of within-subject variability in color thresholds and to validate the CVS test. The data sets provide essential information on inter-subject variability, the effects of normal aging on RG and YB thresholds, and the spread in RG color thresholds in deutan and protan subjects. A statistical model was developed to optimize the parameters of the CVS test and to predict the limits of what can be achieved in color assessment. The efficiency and repeatability of the CVS test were then assessed in 84 subjects. The results match model predictions and reveal close to 100% test efficiency. The test takes between

Color vision assessment‐2: Color assessment outcomes using single and multi‐test protocols

“…The ranking of RG CAD thresholds for deutan subjects and the labeling of those who pass and those who fail the HW‐A lantern reveal the significant overlap in RG CAD thresholds among deutans who pass and deutans who fail the lantern test. This is due mainly to the large within subject variability observed in repeated HW‐A lantern tests 48 and the much smaller within subject variability observed in CAD thresholds 49 . The results also illustrate clearly the inequity of this protocol when less severe deuteranomalous subjects fail and other subjects with more severe loss pass.…”

“…This is due mainly to the large within subject variability observed in repeated HW-A lantern tests 48 and the much smaller within subject variability observed in CAD thresholds. 49 The results also illustrate clearly the inequity of this protocol when less severe deuteranomalous subjects fail and other subjects with more severe loss pass. All deutans with thresholds less than ≤2.34 CAD units pass the HW-A test.…”

“…The HW‐A lantern shows considerable variability of outcome in repeated tests 2 . As a result of this large variability and also the smaller, but significant within‐subject variability in CAD thresholds, 49 there is no clear distinction between deutans who fail and those who pass the HW‐A lantern (Figure 1). The dashed black line in Figure 2 corresponds to an “equivalent” threshold of four CAD units.…”

“…This estimate assumes equal numbers of males and females and 2% prevalence of acquired deficiency. 49 In the absence of minimum color vision requirements that can be classed as safe within a given occupation, the CAD test makes it possible to use an "equivalent" threshold to reduce the variability associated with current protocols without affecting the number of deutans and protans who pass.…”

Color vision assessment‐1: Visual signals that affect the results of the Farnsworth D‐15 test

“…The second paper 1 evaluates the statistical outcomes of commonly used color assessment tests and examines the efficiency of frequently used single‐ and multi‐test protocols. The third paper 2 assesses the fundamental limits of what one can achieve in color vision assessment and describes a new test that approaches this limit.…”