Ishihara Charts vs Tritan Blue Test in Diagnosis of Optic Neuropathy

Abstract Background There are multiple causes of optic neuropathy and the correct diagnosis is most often made on the basis of clinical history and examination. Optic neuropathies generally result in decreased visual acuity, altered color vision, and visual field defects in the affected eye. A relative afferent pupillary defect (RAPD) is often present when the optic neuropathy is unilateral or asymmetric.1 Objective to compare between the accuracy of Ishihara charts and tritan (blue) test in detection of early color vision changes in optic neuropathy. Methods A comparative observational cross-sectional study of 50 eyes divided into two groups, the study was conducted at Ain Shams University Hospitals and Ophthalmology Clinic for 6 months long included Patients with optic neuropathy. Results Marginal Homogeneity test was used to show relation between Ishihara charts grades and Tritan (blue) test grades of color vision in different types of patients. It showed no superiority of tritan (blue) test over Ishihara charts in cases of optic neuropathy except for glaucoma patients (P value <0.001). Using one way ANOVA test, relation between OCT NFL findings and Ishihara charts score in glaucoma patients was insignificant (P value 0.90) while relation between OCT NFL findings and tritan (blue) test score in glaucoma patients was significant (P value 0.03). Relation between visual field changes and Ishihara charts score in glaucoma patients was insignificant (P value 0.09) while relation between visual field changes and tritan (blue) test score in glaucoma patients was significant (P value 0.01). Conclusion Our study concluded that tritan (blue) test was more sensitive to detect color vision deficiency in glaucoma patients more than Ishihara charts. There was no difference between both tests in other cases of optic neuropathy. So, Our vision to Ishihara charts as the first line color vision test in ophthalmological examination should be changed –at least- in certain cases as a start.