A COMPARATIVE-STUDY OF HARDY-RAND-RITTLER AND ISHIHARA COLOR PLATES FOR THE DIAGNOSIS OF NONGLAUCOMATOUS OPTIC NEUROPATHY

Objective: To determine the ability of the Hardy-Rand-Rittler (HRR) an d Ishihara colour plates to detect acquired colour vision defects in p atients with nonglaucomatous optic neuropathy (NGON). Design: Prospect ive study. Setting: Neuro-Ophthalmology Unit of the Wilmer Eye Institu te, Baltimore. Patients: A total of 178 consecutive patients (349 eyes ) referred to the Neuro-Ophthalmology Unit and the General Eye Service of the Wilmer Eye Institute and examined by two of the authors were e nrolled from July 1992 to June 1993. Outcome measures: Results of test ing with HRR and Ishihara plates. Results: Among the 202 eyes that wer e found to have no ocular disease on neuro-ophthalmologic testing, the HRR plates gave a normal result in 168 (83.2%), compared with 196 (97 .0%) with the Ishihara plates (p < 0.0001). The HRR plates detected an acquired colour vision deficit in 48 (87.3%) of the 55 eyes with NGON , compared with 38 (69.1%) for Ishihara plates (p = 0.001). The values for the eyes with NGON with a visual acuity of 20/25 or better were 7 6.5% (13/17) and 35.3% (6/17) respectively (p = 0.008) and with a visu al acuity less than 20/25, 92.1% (35/38) and 84.2% (32/38) respectivel y. Conclusions: For patients with unilateral or bilateral NGON, HRR pl ates are more likely than Ishihara plates to detect a colour vision de fect, particularly when the visual acuity is 20/25 or better, However, neither test is sensitive enough to be used as the sole criterion for the diagnosis of NGON. The results of comparison of colour perception of the two eyes may be move useful than absolute colour vision respon ses, particularly in patients with unilateral disease.