We should all be fairly familiar with the facts of color deficiencies, but I’ll quickly summarize a few key points before proceeding. First of all, the term “color blindness” actually only applies to people who have the inability to see any color, meaning their world is only shades of grey. This condition is quite rare.
What is more common are color deficiencies, in which a person still sees colors but cannot distinguish between certain hues. Most deficiencies result in the inability to distinguish between shades of red and green (deuteranopia and protanopia), but there are also some varieties in which it is more difficult to distinguish between blues and yellows (tritanopia).
Deuteranopia versus protanopia
Red-Green Color deficiencies can be split into two main categories: deuteranopia and protanopia. For both, reds and greens are not the only colors affected. Most have difficulty distinguishing browns, reds, oranges, and greens, but pale colors can also pose a problem and blues and purples can be equally confusing. Deuteranopia is the most common color deficiency, affecting up to 6% of the total male population and about 0.4% of the female population. Protanopia is found in about 2% of the male population and only 0.05% of the female population.
Tritanopia is not a sex-linked trait (it’s linked to chromosome 7 rather than the X chromosome), so men and women are affected equally. However, tritanopia is quite rare, with most study estimates averaging about 1 in 10,000 people affected. Tritanopia can also be acquired in life through injuries, disease processes, or medication side effects. Some studies have shown a higher incidence of tritanopia among alcoholics.
In my experience, patients suffering from deuteranopia or protanopia often report more difficulties performing day to day tasks, possibly because we live in a world that has associated green with go/good and red with stop/bad. Several studies have demonstrated protans have more difficulty distinguishing red traffic signals and therefore are more likely to have an accident. Due to these studies, there are many countries that won’t allow a colorblind individual to obtain a commercial driver’s license.
This article is going to focus on deuterans and protans, since they are the patients you are more likely to encounter in the office and also because most technology on the market today addresses this population.
The effects of color deficiency
For those of us who aren’t color deficient, it may be difficult to fully comprehend how the disease could be devastating, especially since most individuals can still correct to see 20/20 or better. How could the inability to distinguish colors be more than just an inconvenience?
For some careers, a diagnosis of color deficiency can wreck a person’s livelihood. I recently had a patient who graduated from pharmacy school, landed a highly-competitive job in the biggest hospital in the city, moved himself and his family and bought a house, but then lost the job when he failed the color vision screening test during his orientation week. He knew how to distinguish pills due to their physical appearances and markings, but since he couldn’t rely on his perception of color to also aid in his identification the hospital viewed him as too much of a liability.
For another patient, he had worked as an electrician at a company for 15 years, but then after failing a color vision test during his physical screening he was informed that he would lose his job if he couldn’t pass it on a second attempt. If there were a way to correct color deficiencies, it could make a significant impact on the lives of many people.
Can color deficiency be fixed?
And so we are brought to the big question: is there a way to “fix” color deficiency? The short answer is: No. Any product or doctor promising complete correction of color deficiencies should be approached with a healthy amount of skepticism. That being said, there are ways to modify how colors are perceived and help color deficients perform better in their day to day lives.
Most products available to aid in color deficiency are filters of some nature. The XChrom (by Art Optical) is a rigid gas permeable lens that has a deep red tint and is worn in the non-dominant eye. It allows clues to help differentiate between confusing hues by giving them new distinct values of light and dark. In this sense, patients aren’t seeing “new” colors but rather are seeing a wider range of shades of the same color which can improve their abilities in color matching and identification. Due to the tinted nature of these lenses, there is a slight monocular reduction in brightness, but most patients are able to adapt to this as easily as they can adapt to monovision contact lenses.
While tinted contact lenses like the XChrom have been around since the 1980s, some types of spectacle lens filters have debuted in the last decade and have been receiving a lot of hype. One of the most publicized and widely available are Enchroma lenses.
Enchroma was established in 2012 and the technology was originally a happy accident. The founder, Don McPherson, specialized in creating protective eyewear for surgeons working with lasers. The lenses were made to filter out potentially harmful wavelengths of light, but in the process also made differentiating between blood and tissues easier. It was later discovered the glasses could also help color deficient individuals. The lenses selectively filter incoming light and emphasize certain spectrums while downplaying others, essentially trying to normalize the distribution of photons absorbed.
Just as there is a significantly varying severity of red-green color deficiencies, there is a wide variety of responses to Enchroma lenses. As a doctor who has worked with Enchroma lenses for nearly 3 years and fit numerous patients, I’ll warn you not to expect a theatrical, heartwarming response every time you put these lenses on a patient. What you can expect is a fair amount of patients going “Oh, that’s awesome!”
There will also be a decent amount of patients who will shrug and defeatedly admit they don’t notice a difference. I would estimate about 10% of those who try the lenses have the YouTube-worthy emotional breakdowns.
There are some key points you need to keep in mind when fitting patients in these types of lenses and a lot of it has to do with appropriately setting up patient expectations, as well as your own.
Let’s call it . . . performance enhancement
The biggest takeaway is to let patients know these lenses do not cure color deficiencies or color blindness. They can help their ability to distinguish between confusing hues and better appreciate their surroundings. If a patient expects these lenses to help them pass an Ishihara color plate test, these lenses will not do that. I have not encountered any technology that will. All of the aids I have encountered should not be used for diagnostic tests.
However, they can be used for performance tests. Filtered lenses have been shown to occasionally help in the Farnsworth D-15 color test and the Farnsworth lantern test. Some employers are more flexible and will allow substitution of these tests in place of the Ishihara or allow a proficiency test while wearing the filters to demonstrate ability to differentiate particular colors consistently in a work environment.
It is crucial to educate patients to check with employers as to specific requirements and whether visual aids are permitted while taking the tests.
As soon as you put these lenses on a patient, most will immediately ask to see the “number dot coasters”. People wrongly assume that the lenses are only beneficial if it allows them to pass the Ishihara test. Since the lenses won’t, I often won’t let patients look at the plates at first. Instead, I’ll tell them to walk around in the glasses, usually for about ten minutes or so, because sometimes it can take time for the brain to adapt to the lenses.
Test-driving the technology
My practice, The Eye Bar, is located on the corner of a city block and there are big planter displays of pink and purple flowers that serve as a great demonstration for the lenses. We also have a few objects in varying color ranges for patients to examine, such as a tie striped in alternating shades of purple and lilac. At first, I recommend the patients try to avoid taking the lenses on and off but to wear them for at least a few minutes in order to adapt.
Some patients recognize the difference right away, but for others it can be a more subtle change that is more appreciated as the lenses are worn longer. Once the patient has had a significant amount of time to adapt to the lenses, and if they can appreciate an improvement from the lenses, I will then show them the Ishihara test, if prompted. I will again educate that the lenses will not allow them to pass this test, but that the patient should evaluate whether they feel the lenses could improve their quality of life.
As I mentioned before, I still have a moderate amount of patients who try the filters and have no appreciable improvement in color differentiation. If I have a patient interested in the filters, I highly encourage them to come try the lenses in person before purchasing. Online tests and simulations cannot replace a personal test-drive of the technology.
As a non-color deficient individual, when I put on Enchroma lenses they feel essentially like sunglasses. I can notice that colors seem a little altered, but no more so than if I was wearing a regular tinted lens. However, our optician/owner, Jared Plank, is color-blind, and his experience is remarkably different.
“I was able to demo the lenses 3 years ago when we became a dealer. I could see that reds appeared more intensely red, greens were more green and most colors just seemed to pop more. Then I noticed a bright purple stripe on someone’s sweater and was in shock at the beauty and “purple” of the color. When driving, red tail-lights, stop signs, and traffic lights are much more pronounced and the green light, which has always looked perfectly white, had a green hue! I know I am still color deficient, but the world is much brighter and colors are more beautiful with my Enchroma lenses.” - Jared Plank
Enchroma lenses can be placed into any frame and can be plano or prescription, single vision or progressive. All the lenses have a slight tint to them, coming in “indoor” and “outdoor” varieties
Not a panacea, but an option
Just as with anything that isn’t fully understood and doesn’t consistently work for every patient, color vision aids can be frustrating and many doctors shun them. However, after seeing first hand how such aids can be appreciated by patients and improve their quality of life, I think it’s a technology that should definitely be considered in every practice for those patients seeking it.