Donald McPherson

Dr. Don McPherson is currently Chief Science Officer at EnChroma in Berkeley, CA, where he develops technologies to assist the colorblind. Don designed EnChroma’s line of eyewear for the colorblind which are now sold worldwide. Don collaborates with vision scientists worldwide who are researching EnChroma’s filters in clinical studies. Don is currently developing lighting systems for the colorblind and continuing his efforts to perfect a contact lens version, both directed towards making for a more equitable learning environment. Recently, EnChroma has extended its knowledge to develop eyewear for other types of color vision diseases, such as cone retinopathy. In 2017 Don and EnChroma were awarded the Tibbetts award by the SBIR for commercializing the NIH-funded research leading to EnChroma.

Don holds a number of degrees in several fields. He received a BGS (Math, Chemistry, Art) from Ohio University, an MS and PhD in ceramics and glass from Alfred University, and was awarded an honorary doctorate from Alfred University in 2018.

Presentation title:  A rose is a rose is a rose: What colorblindness reveals about perception

Abstract: Colorblindness affects 8% men and 0.5% women, with 4 of 5 having anomalous trichromacy, wherein one of the three photoreceptors (cones) is spectrally shifted, overlapping the neighboring cone leading to color confusion. Properly designed filters reestablish more normal photon capture by the cones. Color information is computed at the eye in special cells that pool information from surrounding individual cones. This channel information is sent to the thalamus and then the primary visual cortex (V1), where additional processing stages create visual perception.

Color vision models predict EnChroma eyewear will improve color contrast, in agreement with the colorblind’s experience. I present recent clinical evidence (2019) that EnChroma eyewear help the colorblind make accurate color matches. A 2020 study showed improved color contrast perception above threshold. Performance improved over a two-week period, even without wearing EnChroma eyewear, demonstrating perceptual learning. A 2022 study confirmed this, and, using contrast sensitivity, extended it to show improved threshold performance. The improvement was seen with time of wear, but testing was made without wearing EnChroma eyewear. Cone-specific Visually Evoked Potential (VEP) measurements showed color-evoked signal induced by wearing EnChroma eyewear. The changed VEP in V1 indicates improved cortical color perception, and new perceptual learning.