Development of Colour Modified Visual Acuity Charts and its Applicability in Detection and Diagnosis of Glaucoma

Purpose: Glaucoma is the foremost cause of irreversible vision loss globally. Colour vision function is not a routinely employed vision function test in glaucoma assessment notwithstanding the assumption that colour vision is usually affected by glaucoma. This study developed four colour modified visual acuity charts (red-on-green, green-on-red, blue-on-yellow and yellow-on-blue optotype/background types) and evaluated its applicability in the detection of glaucoma. Methodology: Masked experimental method was used in testing the visual acuities of fifty-four eyes from twenty-seven consenting respondents drawn from two groups- glaucoma and non-glaucoma respondents. They were measured individually across the four colour-modified charts and the traditional black-on-white chart which were all computer designed and projected in the same way automated visual acuity charts are projected. Their visual acuity performances on the modified colour charts were compared with their OCT results. An assumption of glaucoma was made when a difference of +/- ≥0.10 logMAR existed between the VA measured using the black-on-white chart and compared with the four colour test charts. Data were analysed; descriptive and inferential statistics were done with the level of significance set at ≤ 0.05. Findings: When compared against their OCT results, none of the four modified colour vision test charts had sensitivity, specificity and accuracy up to 90%, with most falling below 80%. For all respondents, VA performance was best on the black-on-white and the yellow-on-blue charts, and worst on the green-on-red chart. Unique Contribution to Theory, Practice and Policy: This study shows that although the human visual performance differs across different colour combinations; the use of these four colour modified charts as an alternative visual function assessment test for detection of glaucoma is not effective. This study has exposed the need for more studies to understand the visual responses in more colour combinations.