Colour discrimination and the Cambridge colour test : reliability of discrimination ellipses and trivectors in colour space

Abstract: The evaluation of colour vision and discrimination of an individual forms an integral part of routine eye and vision examinations. Colour vision deficiencies have a high prevalence and defects of colour vision can be detected in an optometric practice by means of a variety of tests available. Colour vision can be assessed qualitatively and quantitatively using tests that are sometimes grouped as arrangement, matching and vocational tests or pseudo-isochromatic plates. Specifically, a more sophisticated computerised procedure, the Cambridge Colour Test (CCT) was developed using the basic principles of traditional pseudo-isochromatic plates and modern technology of randomized luminance to evaluate colour function or discrimination. Unlike previous computerised colour vision tests, an advantage of this (CCT) computer-controlled test is that the difference in chromaticity between target and background is adjusted automatically according to the performance of the patient, thereby preventing a loss of time needed in calculating preliminary equations of luminance for each subject or for each part of the visual field. This is believed to be the first study that aims to extensively investigate the reliability and repeatability of results produced by the two testing protocols of the CCT, namely the Trivector test and the Ellipse test’s shorter 8-vector and longer 20-vector testing method, using both univariate and multivariate statistical analyses. Results from this dissertation provide test and retest reliability measures (including, for example, Coefficients of Repeatability) and new parameters on discrimination ellipses that are not provided by the CCT were calculated to better understand the results that are produced by participants with normal trichromatic vision. Although not the purpose here, limited normative data has also been provided in this study, which perhaps can be used comparatively with past and future studies. Multiple CCT measurements, using both the Trivector and Ellipse tests were performed for the right eye only of each participant selected. Where necessary, colour tests were performed through the habitual spectacle compensation for the right eye concerned. Two measurements (test and retest) of both the Trivector test and also the Ellipse test were measured for all participants (N=20) to assess the reliability of test and retest measurements, and the 8- and 20-vector testing methods were both performed twice on all subjects (N=20) to investigate which CCT test protocol produces the most reliable results and whether or not the 8- and 20-vector methods could be used interchangeably. Two 90-minute sessions, separated by a short...M.Phil. (Optometry