Purpose:
We examined the effects of traumatic brain injury on color perception and performance on the Farnsworth-Munsell 100 hue test and Dichotomous D-15 test.
Methods:
The primary subject, CK, a 14-year-old female reports "everything looks bluer since my snowboarding accident" in which she sustained traumatic brain injury to the occipital region. She had no prior history of color deficiency or color perception anomalies. Visual acuity, visual fields and ocular structures are normal in each eye. Color vision testing under a Macbeth lamp with the Farnsworth-Munsell 100 hue test and Dichotomous D-15 test indicate color confusion along axes that are non-standard in acquired color vision loss.
Results:
Color vision testing remained consistent on three visits 4 months apart. Farnsworth-Munsell 100 hue test displays errors in the red, purple-red and purple zones. The D-15 axis although closest to Protan is rotated counterclockwise from the traditional Protan axis. These findings may explain the bluer color perception when interpreted in the context of the CIE chromaticity diagram.
Conclusions:
In acquired color vision loss, outer retinal disease and media changes traditionally result in blue-yellow defects whereas inner retinal disease, optic nerve and visual cortex pathology result in red-green color defects. Although infrequently reported, injuries to the occipital cortex can present a variety of color vision defects ranging from complete loss (achromatopsia), to the classic red-green or blue-yellow defects. Our case of occipital region trauma associated with increased blue color perception and novel color confusion axes resulted in a uniquely selective dyschromatopsia without affecting visual acuity or visual field. This may indicate the presence of secondary color vision areas adjacent to primary visual cortex.
Keywords: trauma • color vision • visual cortex