Comparing the validity of an online Ishihara colour vision test to the traditional Ishihara handbook in a South African university population

Background: Colour vision tests are becoming increasingly available on online platforms to the ordinary internet user. Limited research has been conducted to establish the validity of these tests for use as screening tools for colour deficiency. Aim: To compare the validity of an online version of the Ishihara colour vision test (OV-PSI) with the traditional Ishihara handbook (PSI). Setting: This study was conducted at the University of KwaZulu-Natal's optometry clinic in Durban, South Africa, in 2014. Methodology: One hundred and twenty participants (N = 120), between the ages of 18 and 25 years who visited the University of KwaZulu-Natal's eye clinic between June and August 2014, were recruited to the study. Colour vision testing was administered using the Ishihara 38 plate test and the ColBlindor Ishihara 38 plate colour vision test available online. Both tests were administered on normal sighted university student participants under standardised conditions, and responses were captured on Ishihara recording sheets. Data were analysed using the Statistical Package of Social Science (SPSS) version 21. Results: Of the 120 participants, 47.5% were men and 52.5% were women with a mean age of 20.64 ± 2.09 years. Results demonstrated that 5.3% of men (N = 3) were colour deficient, resulting in a prevalence of colour deficiency for the sampled population of 2.5%. Results of the two testing methods were compared, revealing sensitivities and specificities for both tests of 100%. However, while the online test correctly discriminated colour deficient participants from colour normal participants, it was unable to correctly identify the severity or type of deficiency. Conclusion: The online version of the Ishihara test used in this study proved a valid screening tool for colour vision deficiency. It presents the opportunity for self-screening via convenient online platforms. However, if colour deficiency is detected using this online tool, it is recommended that further clinical investigation be undertaken for a more accurate diagnosis of the extent of colour vision deficiency.