Determination of Colour Vision Using Ishihara and Dvorine Plates

Abstract

Background: Colour vision is important in everyday life and colour vision deficiency generally lowers the quality of life. The objective of the study was to perform tests and measurements to investigate the prevalence of colour vision abnormalities within a normal sample population of the University of Jos.

Methodology: Colour vision measurements were carried out using the Ishihara and Dvorine colour test plates. The visual acuity measurements were obtained using the Snellen letters. A total number of 115 subjects were tested.

Results: A nalysis of the data resulted in a new empirical relationship for the Colour Deficiency Index (CDI) which was found to be equal to the product of the number of Ishihara plates missed (I) and the number of Dvorine plates missed (D) divided by the coded Visual Acuity number (A) given by the equation This relationship, indicated a colour problem for a CDI of more than 3, while an index of less than 3 indicated a 'normal' colour condition. The results of the physical measurements showed a prevalence of 9.6% colour vision deficiency.

Conclusion: The percentage is high compared to the civilized world having 8.5% , primarily due to the fact that most were acquired and indicated a poor health care.