Your eyes are little globes of technicolor wonder. When you look around at everything around you, the colors you perceive aren’t inherent to the objects you see. Instead, objects absorb light and reflect specific colors that we then see. That red stapler on your desk is only red because that is what is reflected when light hits it. Turn off the lights and your red stapler becomes a dark gray color.
We perceive color as it hits the back of the retina. The retina is lined with millions of cells known as rods and cones that take the colors reflected off of objects as light-sensitive signals and relay those signals to our brains via the optic nerve and pathway. Our brain does the heavy lifting in recognizing that specific signals from specific reflections are a certain type of color. Rod cells are sensitive to different levels of light, while cone cells are more sensitive to differing colors. Humans generally have three types of cone cells that are able to discern different colors and shades. But for approximately 300 million people across the globe, colors aren’t as they seem.
Defining Color Deficiencies
While relatively uncommon, most are at least familiar with the term “color blindness”. These color deficiencies don’t have anything to do with how sharp our vision is or how much light we see, but it does mean the cone cells process colors differently. It affects 1 in 12 men throughout their life and is much rarer in women, where only 1 in 200 will have some kind of color deficiency. It’s often inherited genetically through the mother but has been known to develop over time with age or diseases like diabetes and multiple sclerosis (MS).
There are a few different types of color deficiency that can be separated into three different categories: red-green color blindness, blue-yellow color blindness, and the much more rare complete color blindness. These three different types may seem self-explanatory as to what colors someone may be “blind” to or confuse, but within two of these groups, there are several specific color deficiencies.
For red-green color blindness, there’s:
- Deuteranomaly – the most common type of red-green color blindness where greens will have a more red shade.
- Protanomaly – the opposite of deuteranomaly, protanomaly makes red look more green and less bright.
- Protanopia and Deuteranopia – both make you unable to tell any difference between red and green altogether.
With blue-yellow color blindness, there’s:
- Tritanomaly – which makes blue and green hard to differentiate along with red and yellow.
- Tritanopia – which makes it difficult to tell the difference between certain combinations of colors like blue/green, purple/red, and yellow/pink. Colors all around will look less bright.
Complete Color Blindness
Scientifically known as monochromacy, complete color blindness is much rarer than the two categories above. In other forms of color deficiencies, one perceives colors differently but can still perceive colors as… well, colors! In monochromacy, the rods and cones in your retina have some form of defect. There are different subtypes of monochromacy that are affected by different rod and cone cells taking on abnormal shapes or not being present at all. For these unfortunate people, their visual acuity leaves most legally blind.
Can it be cured?
In short – no, or not yet. But in certain, more common types of color deficiencies, there are ways it can be treated thanks to specially engineered glasses that alter colors. In “color blind glasses”, lenses are specially tinted to shift colors before they hit the retina. These lenses are engineered to pinpoint areas of confusion between colors and separate the confusion into their correct colors.
For someone who is red-green color blind, for example, these special glasses will be able to take the more confusing shades of red and green and enhance them to be more contrasting, allowing the wearer to see them as they actually should be! These lenses are particularly helpful for helping people pick out matching clothes without help.
Accessibility for all!
It’s increasingly becoming important for technologies to incorporate accessibility options for people who have different vision impairments. Behind the glitz and glam behind your favorite user interface, a lot of thought has gone into making options available that can filter certain colors, make text bolder or bigger, increase the contrast of the screen, or use a screen filter that isn’t as hard on the eyes. If the screen of your personal device is bothering you, you can ask us for advice on how to adjust it to be easier to see, or you can navigate to the accessibility settings and adjust them as you deem fit.
Color deficiencies are another thing we look at and test for during your comprehensive examination. When we have you in the examination room, we may ask you to flip through cards that test different aspects of your vision, like depth perception and color differentiation. By doing this, we can provide the best options available to give you the most of your vision as possible.
Image courtesy of AAO: How Color Blindness Is Tested