A Retrospective Study on the Usefulness of ColorDx^® CCT-HD^TM for Cone Contrast Testing in Congenital Color Vision Deficiencies

<p> 【Purpose】ColorDx^® CCT-HD^TM (ColorDx^®) is a device with a software that measures the contrast sensitivities of L-, M-, and S-cones. It not only detects but also classifies color vision deficiencies. In this study, we examined the usefulness of ColorDx^® in patients with congenital color vision deficiencies.</p><p> 【Subjects and Methods】Subjects were 10 males (age range, 6-12 years) suspected of congenital color vision deficiencies. All the subjects had no abnormal findings in the anterior segment, media, or fundus, and had corrected visual acuity of 1.5 or better. The Ishihara 38 plates color vision deficiency test Ⅱ, the Farnsworth dichotomous test D-15, an anomaloscope test, and the ColorDx^® test were performed. The ColorDx^® results for the cone sensitivities with a score lower than 75 points were classified as “color deficient”. Using the medical records, we retrospectively investigated the agreement between the results of the ColorDx^® and anomaloscope tests regarding sensitivity and types of congenital color vision deficiencies classified.</p><p> 【Results】All the subjects were detected with color vision deficiencies by both anomaloscope and ColorDx^® and thus, the detection sensitivity was 100%. Of the 9 subjects diagnosed with deutan by the anomaloscope test, 6 were also detected with abnormality in M-cone alone by ColorDx^® and the classified types of color vision deficiencies by both tests were consistent. One subject with protan and 3 subjects with deutan diagnosed by the anomaloscope test were also detected with abnormalities by ColorDx^® with a score lower than 75 points in more than one cone. However, the lowest scores for these subjects were seen in the corresponding L- and M-cones, respectively.</p><p> 【Conclusion】The results suggested that the ColorDx^® test is useful as a screening test for color vision deficiencies. When abnormality is observed in more than one cone, using the lowest score to determine the type of the color vision deficiencies could be valid.</p>