Special glasses help colorblind people see more hues, even with glasses off

A new study enhanced color vision for individuals with the most common type of red-green color blindness.

colorful flower
  • Special glasses constructed with technically advanced "spectral notch filters" enhance color vision for individuals with the most common type of red-green color blindness.
  • The ability for colorblind participants to experience expanded color channels was demonstrated even after they took the glasses off.
  • At least 8 percent of men and .5 percent of women have red-green color vision deficiency (CVD).

A new study may be a breakthrough in treating the most common type of red-green color blindness.

Research conducted by UC Davis Eye Center in collaboration with Frances INSERM Stem Cell and Brain Research Institute discovered that special patented glasses constructed with technically advanced "spectral notch filters" enhance color vision for individuals with anomalous trichromacy.

Interestingly, the ability for colorblind participants to experience and discern expanded color channels was demonstrated even when they were not wearing the glasses.

Red-green color blindness

At least 8 percent of men and .5 percent of women have red-green color vision deficiency (CVD). That's 13 million people in the United States and 350 million globally.

Someone with "normal" color vision is able to experience one million hues and shades, but those with CVD see a diminished range of colors. They see colors that are more muted and washed out, and some colors are difficult to distinguish and may cause confusion.

This UC Davis study analyzed the impact of spectral notch filters—EnChroma glasses—on boosting the chromatic responses of observers with red-green CVD over a two-week period of usage. The filters are engineered to increase the separation between color channels to assist colorblind individuals in seeing colors more vibrantly and precisely.

Research findings 

The study, which was published in the journal Current Biology, had participants with CVD color blindness wear either the special filter glasses or placebo glasses.

"Over two weeks, [the participants] kept a diary and were re-tested on days 2, 4 and 11 but without wearing the glasses," UC Davis Health detailed in a news release statement. "The researchers found that wearing the filter glasses increased responses to chromatic contrast response in individuals with red-green color blindness." It's still not clear how long the enhancement to vision lingers after the filtered glasses are taken off, however evidence shows that the effect lasts for a substantial amount of time.

"Extended usage of these glasses boosts chromatic response in those with anomalous trichromacy (red-green color vision deficiency)," said John S. Werner, a professor of ophthalmology and a leader in vision science at UC Davis Health. "We found that sustained use over two 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."

Seeing color 

The researchers in this study think that the study's results suggest that modifications of photoreceptor signals activate a plastic post-receptoral substrate in the brain that could possibly be exploited for visual rehabilitation.

"When I wear the glasses outside, all the colors are extremely vibrant and saturated, and I can look at trees and clearly tell that each tree has a slightly different shade of green compared to the rest," said Alex Zbylut, one of the colorblind study participants who got the placebo glasses first and then tried the special filter version afterwards. "I had no idea how colorful the world is and feel these glasses can help colorblind people better navigate color and appreciate the world."

Read the study in Current Biology here.

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