EnChroma lenses are glasses designed to improve and modify some aspects of color vision deficiency for color blind people. The glasses were invented by Dr. Donald McPherson in 2002. Wearing the glasses results in subtle differences when color blind people look longer and more carefully.
Glass scientist Dr. Donald McPherson invented EnChroma glasses by accident. He originally invented this type of lens to protect surgeons during laser operations. In 2002 at the Ultimate Frisbee tournament in Santa Cruz, California McPherson lent a pair to a friend who was color blind. His friend saw colors he had never seen before. McPherson started studying color blindness, and with Andrew Schmeder founded the company EnChroma Inc. in 2010 to sell glasses that compensate for color vision deficiency. EnChroma glasses target people with difficulties in distinguishing reds and greens. The first pair of commercial glasses were released in 2012.
The optical filter used in EnChroma lenses can improve or modify aspects of color vision deficiency (CVD). EnChroma lenses focus on the most common color vision deficiency which is caused by the red and green retinal cone cells that, when responding to light, coincide. The most common form of color blindness is known as deuteranomaly, it is genetic and an X-linked trait that affects up to one in every 12 men (8%) and one in 200 women (0.5%). To eliminate the overlapping of the wavelengths of light, there is an optical material called a 'multi-notch' filter, is capable of removing the exact wavelengths of light in the location where it overlaps, getting a simplified differentiation of colors. The glasses block specific wavelengths to create a clearer separation of different color signals so that they can be better calculated by the brain. The separation of signals allows most people with CVD to distinguish colors, but the glasses will have little to no effect on the 20% of color blind people who have severe color impairment.
The filters designed by the method have a spectral transmittance that can be essentially described as a multi-band filter, made up by a plurality of passbands interleaved with stopbands. This technology makes it possible to remove the overlapping of colours.
The use of glass in lens manufacturing has reduced due to the availability of new lens materials offering different characteristics. Lens research is aimed at finding the optimum materials for the most common vision deficiencies. EnChroma technology is one of the few materials to compensate for CVD. Trivex eyeglass lenses were first developed by PPG industries in the United States. The lenses can be progressive or photochromic. They are significant in allowing better vision sharpness and eye protection, and are also comfortable to wear since the weight of the material is minimized. The tinted plastic lens used to make EnChroma glasses is coated in approximately 100 layers of dielectric material. A coating can be applied on both sides of the lens to eliminate light reflection and to protect the lens itself from scratches. A predecessor of the Trivex lens with similar characteristics is made from polycarbonate.
EnChroma lenses are used in various types of glasses, including sunglasses, indoor glasses, infant, industrial safety and sports glasses.
Sunglasses were the first product to use EnChroma lenses. They can be used in various lighting conditions, even in bright indoor environments, and assist people affected by deuteranopia and protanopia. They protect those who are affected by color blindness from solar ultraviolet and blue light and do not let solar radiation with a wavelength shorter than 450 nanometers pass through. They block just one or two colors (usually green and blue), permitting people to see colors such as dull brown or yellow. This is due to a specific coat that increases the brightness of colors and provides protection from UV rays.
Different models of sunglasses exist, according to the color deficiency the person suffers from.
This version of the glasses for people with CVD can be used indoors, but they work best in bright lighting and have applications for people who spend a lot of time facing a computer monitor. Students with color blindness can have a benefit from the glasses, because they can understand particular color-coded information better at their school or at university.
There are also particular glasses for athletic people, for children and for industrial safety use which are made of particular materials such as polycarbonate. This makes the glasses stronger and less breakable. These kind of lenses are able to correct severe vision deficiency but they do not need additional lens thickness to achieve this. Trivex eyeglass lenses offer the same characteristics as those that are made for athletic people or children and provide an alternative material to polycarbonate.
The glasses are available in single vision lenses, bifocals, and progressive lens. The sunglasses are also used by some senior citizens to help with sunlight sensitivity or due to medical conditions such as diabetes, glaucoma, macular degeneration, cataracts, multiple sclerosis, and eye cancer.
The Qassim University and the Pacific University conducted joint experiments.
The Qassim University experiment involved 25 males aged from 20 to 25 years. Two of those 25 were excluded because of a vision disease that may affect the CVD deficiency.
The Pacific University College of Optometry's experiment tested whether the glasses helped people with particular deficiencies improve the way they see colors. The study involved ten individuals with hereditary deficiencies (nine males and one female from age 19 to 52).
The EnChroma Cx-14 filters did not significantly influence the vision of CVD subjects but, for two of them, the error score was improved.
In 2018, researchers from the University of Granada studied EnChroma lenses and proved that they merely helped color blind people to see the same colors in a different way since the colored filter altered the way colors appeared in their eyes.
The research involved 48 color blindness volunteers, four were women and 44 were men, aged between 14 and 64. These participants were already aware of their own condition of CVD. The study concluded that, although an improvement in color vision has been accomplished since the colors are enhanced by the effect of the glasses, the technology could not be considered completely effective because the color vision it offers was not identical to the non-colour blind individuals.
In order to evaluate the effectiveness of the glasses, the color vision of the participants was evaluated without the EnChroma glasses using the Ishihara test, Farnsworth-Munsell 100 hue test, and a color-naming test (with 21 colors from an X-Rite GretagMacbeth Chart). The tests were repeated under the same conditions while wearing EnChroma glasses. In order to measure the full effect of EnChroma lenses, an adaptation time of 30 minutes was given to the participants. Between the two sections of the tests, more than 2 weeks passed in order to reduce the likelihood of participants memorizing the color patterns.
The researchers claimed that the effect of using EnChroma glasses is similar to glasses where the use of color filters changes the user’s perception and increases the contrast among the colors, such as those used for shooting or hunting. The research showed that EnChroma glasses did not reveal any improvement in the Ishihara test and Farnsworth Munsell 100 hue test.
In other research on the effects of wearing EnChroma glasses on red-green CVD, R. Mastey recruited 27 males: eight deuteranomalous, ten deuteranopic and nine protanopic, while E. J. Patterson recruited fifteen males: seven deuteranopic, six deuteranomalous, one protanomalous and one protanopic. For the research, the researchers used the Color Assessment and Diagnosis (CAD) test that provides chromatic discrimination thresholds.
In 2015 Dr. Blake Porter of the University of Otago conducted an experiment with 406 participants, of whom 42 already used EnChroma glasses. The participants were asked questions about their color blindness, their personal experience with the lens and the effects of those on their life and on the way they saw the colors.
90% of the participants said they would recommend them to other people, and more than 50% of those people stated that EnChroma glasses improved their life. 10% of the remaining participants reported that the glasses did not have any impact on their life. 40% of the participants identified green as the color range that changed the most.
In some subjects, improvements due to the technology do not happen immediately because the brain requires time to rewire and create new links, neuroplasticity. Neuroplasticity depends on the age of the individual. Younger people reported that they perceived little changes from the first time they wore glasses and a second wearing in which they have had time to adapt to the technology. Middle age people reported that the colors continued to change from the first time they wore the lens, and that color brightness and enhancement got better with time. Most participants related that the biggest effects of the glasses are not perceived initially but after a few days, confirming that the neuroplasticity takes time.
The experiment demonstrated that the glasses have a positive effect on the everyday life of those subject to color blindness. The glasses achieve better results with some colors than others. The biggest improvements are achieved with greens, followed by purples, pinks, and reds. Subtle differences emerged when users looked longer and more carefully.