Ishihara's Tests for Color Blindness: A useful Indicator of Visual Involvement in Multiple Sclerosis

Abstract

Because vision commonly is affected in persons with multiple sclerosis, it would be helpful to have a bedside test capable of identifying abnormalities that are not readily apparent. This study evaluated the sensitivity and specificity of the first 11 plates of Ishihara's Tests for color blindness (1995 concise edition) as compared to visual evoked potentials in patients with multiple sclerosis reporting normal vision. Forty-five multiple sclerosis patients and 42 controls, aged 25 to 44 years, were assessed. After examination of vision by a neurologist, Ishihara's Tests for color blindness and visual evoked potential tests were administered under conditions similar to those encountered in a neurologic practice. The specificity for each test was defined by the responses of the control population. In differentiating individuals with multiple sclerosis from controls, Ishihara's Tests for color blindness was as sensitive (62%; 28/45) and specific (100%; 42/42) as visual evoked potentials (sensitivity = 58%, 26/45; specificity = 98%, 41/42). Ishihara's Tests for color blindness identified a different population of patients and probably measured a different aspect of visual function than did visual evoked potentials. Ishihara's Tests for color blindness appeared more likely to identify patients with a long disease duration, while visual evoked potentials better identified patients with a history of optic neuritis. Ishihara's Tests for color blindness may be a simple and cost-effective adjunct for detecting and following the visual abnormalities of patients with multiple sclerosis.