Individuals with color vision deficiency (CVD), commonly referred to as “color blindness”, experience colors in a unique way – certain colors of the visual light spectrum become muted or almost indistinguishable from other colors. There are various causes for this deficiency including diabetes, multiple sclerosis, or even simply the aging process, but the most common cause is through genetic inheritance. The recessive allele for color blindness is X-linked which means that it is only carried on the X chromosome; consequently, men are more likely to have this condition than women because men only have one X chromosome whereas women have two. Approximately 1 in 8 men and 1 in 200 women in the world are affected with CVD (“Colour Blindness”, n.d.). However, innovative visual lens technology developed by the company EnChroma may provide a solution that will allow these individuals to experience all of the colors of the rainbow in all their bright and vibrant glory.
Although EnChroma products may look like ordinary sunglasses at first glance, don’t be fooled – they are equipped with lenses that are specifically designed to provide the wearer with heightened color perception in addition to providing protection from ultra-violet radiation. Developed by Dr. Don McPherson, Ph. D in Glass Science at Alfred University, under research sponsored by the National Eye Institute, these optical filters were originally created to provide protection during laser eye surgery; however, Dr. McPherson discovered that his special lens formula also had transformative properties on color appearance. Upon further research which included clinical trials of prototype lenses conducted at the UC Berkeley School of Optometry and the UC Davis Eye Center, the results indicated that these lenses could assist people with color vision deficiency (“Technology | EnChroma”, n.d.). As a result, the company “EnChroma” was founded and now offers lenses that perform either indoors on computer screens or outdoors in the sunlight and come in a variety of different styles for men, women, and children; additionally, lenses can be made with your prescription if you normally use corrective lenses for distance vision.
But how exactly do these glasses work? Well, before we can answer this question, we need to understand the topic of spectral overlap and the absorption of light. Our eyes have rod and cone cells that are located on our retinas; there are anywhere from 6 to 7 million cone cells in the eye, and they are responsible for the detection of color and are concentrated around the fovea which is the area of the retina with the highest visual acuity. There are three distinct classes of cone cells that each absorb a specific color: L-cones absorb mainly red light, M-cones absorb mainly green light, and S-cones absorb blue light. These cone cells contain light-absorbing molecules called “photopigments” that absorb photons of certain wavelengths and undergo a chemical transformation, causing the cone cell receptor to fire a nerve impulse (“Technology | EnChroma”, n.d.).
Color blindness arises from a deficiency in one of these types of cone cells. People with protanomoly, a type of red-green color blindness, have reduced sensitivity to red light due to the L-cone absorbing too much green light, a condition known as PROTAN deficiency. Likewise, people with deutoranomoly have reduced sensitivity to green light because the M-cone absorbs too much red light (DEUTAN deficiency) (“Technology | EnChroma”, n.d.). Deutoranomoly is the most common type of color blindness (“Types of Color Blindness”, n.d.). Individuals with red-green CVD experience greater spectral overlap of their red and green photopigments than normal. This overlap of M-cone and L-cone signals causes confusion and conflicting information to be sent to the brain; the greater the overlap, the more severe the color deficiency (“Technology | EnChroma”, n.d.). EnChroma’s assistive lenses alter the way that light is received by the eyes so that spectral overlap is minimized and the distinction between red and green light is more prominent.
In order to create the lenses, an advanced computer model was developed to simulate color vision under any type and extent of color vision deficiency. The model was created using information gathered from the most recent research on the genetic basis behind CVD and the possible types of spectral variations that can occur due to anomalous photopigments, which were then interpreted into a model of color perception developed according to a branch of psychology known as perceptual psychophysics. Perceptual psychophysics is the study of how our senses transform physical stimuli from our environment into perceptual phenomena (“Technology | EnChroma”, n.d.). This computer model allows EnChroma to test out lens designs and predict their effectiveness before they are even produced; it simulates the visual appearance of both natural and man-made colors and allows them to see how any given filter affects the perception of color when placed in front of the visual system. The filter design itself is optimized with the help of linear programming; this mathematical technique is a special type of algorithm used for solving large-scale resource allocation problems (“Technology | EnChroma”, n.d.). EnChroma’s linear program takes into account both cost and constraint, and it can generate a unique, optimal solution to any given problem out of millions of possible filter designs within seconds.
The general class of filters that the company produces are known as multi-notch filters; they contain one or more sharp “notches” or “cut-outs” in the visible light spectrum. Lenses that improve red-green color blindness have this notch filtering primarily in areas of maximum spectral overlap between red and green photopigments; the resulting effect is similar to driving a wedge between L-cone and M-cone signals, which causes them to separate, effectively improving color vision in color blind individuals (“Technology | EnChroma”, n.d.). Although this eyewear technology improves color perception, it is important to note that these products are not a cure for color vision deficiency; they only function as optical assistive devices to allow CVD-affected individuals to experience color in a new way.
This cutting-edge spectral filtering technology provides greater insight into our understanding of color vision science and is sure to open the door to a world of innovative possibilities – a world full of color.For more information about EnChroma, please visit their website.
Colour Blindness. (n.d.). Retrieved January 13, 2016, from http://www.colourblindawareness.org/colour-blindness/
Technology | EnChroma. (n.d.). Retrieved January 13, 2016, from http://enchroma.com/technology/
Types of Colour Blindness. (n.d.). Retrieved January 13, 2016, from http://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/
Editor: Shreya Singireddy