Source/Disclosures
Disclosures: Werner reports support from the National Eye Institute. Please see the study for all other authors’ relevant financial disclosures.
July 30, 2020
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Special filters increase contrast in color vision deficiencies

Source/Disclosures
Disclosures: Werner reports support from the National Eye Institute. Please see the study for all other authors’ relevant financial disclosures.
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Sustained use of broadband spectrally selective filters achieved an increase in chromatic contrast along with an adaptive response in observers with color vision deficiencies, according to a study published in Current Biology.

“About 6% of males and [less than] 1% of females have anomalies in their gene arrays coded on the X chromosome that result in significantly decreased spectral separation between their middle(M-) and long (L-) wave sensitive cone photoreceptors,” John S. Werner, PhD, University of California department of ophthalmology and vision science, and colleagues wrote. “Broadband spectrally selective filters [that are] proposed to improve the vision of color-deficient observers principally modify the illuminant and are largely ineffective in enhancing discrimination or perception because they do not sufficiently change the relative activity of M- and L-photoreceptors.”

Evaluating the long-term impact of spectral notch filters, 10 color vision deficient male participants wore either commercial notch filter Enchroma or placebo for 2 weeks. Participants kept a diary estimating daily use (mean, 7.7 hours/day; SD = 3.61) and were tested without wearing the glasses at day 2, day 4 and day 11.

Study results showed consistent increase in chromatic response from baseline across the patient population at day 11 (mean increase = 71%; 95% CI , 45- 96%). These findings demonstrate a positive L-M response over time as well as adaptation that carried over without filter use.

“We found that sustained use over 2 weeks not only led to increased chromatic contrast response, but, importantly, these improvements persisted when tested without the filters, thereby demonstrating an adaptive visual response,” Werner said in a press release from UC Davis Eye Center.

Further testing is required to determine how long improvement persists without filter wear, the researchers said in the journal article

“This is a neural effect that may lend itself to adaptation in visual therapies, not just for color vision, but perhaps for other visual modalities as well,” Werner and colleagues concluded.