Color Vision Impairment Through Drinking Alcohol

Is that blue and yellow IKEA sign looking a little blurry? The Goodyear tire logo you spot on your drive to work seems a bit less crisp than usual? Could be the alcohol! As it turns out, alcohol can reduce your ability to distinguish between colors, especially blue and yellow. The reasons have to do with the effect of alcohol on the eyes as well as on the visual cortex of the brain. Let’s find out more!

Color Vision Basics

How do we see colors in the first place? Let’s take a brief look.

• Rods and cones pick up light. When light hits the retina — a light-sensitive tissue at the back of our eyeballs — cells known as rods and cones respond to particular wavelengths and pass that information on to the brain. While cones are in charge of color vision in bright light, rods come into play in darker environments. 

• Color signals are translated in the brain. The brain picks up the signals from the rods and cones and puts them together into a “colorful” picture of the world in front of us. The signals travel from the retina through the optic nerve. After a stop at the thalamus, which acts as a sorting station, the signals reach their final destination — the visual cortex.
• The colors come together to form a picture, “paint by number” style. We have three types of cones, with each sensitive to one of three different color ranges — red, green, and blue — which fall at the long, middle, and short wavelength ranges of visible light. The signals from these cones trigger specific areas of the visual cortex, “filling in” a tiny corresponding part of what forms our overall picture of the world. (Of course, the three colors are just markers that happen to correspond to the beginning, middle, and end of the visual spectrum — there are many specific shades of each color, and various combinations of the three that make the picture in front of us so wonderfully complex.)
  
  There are many glitches in this pathway that can cause problems with color vision. It’s often not an all-or-nothing scenario: we can lose our ability to perceive differences between certain colors or shades or, possibly, fail to recognize certain colors altogether. Here’s an overview:
• Cone cell problems. Sometimes there are problems with the cone cells themselves (in some cases, one or more types can be missing altogether). This is what happens in the case of color blindness, which is a genetic condition that involves deficiencies in the cone cells. For example, if the red cones are missing, we’ll have trouble distinguishing between red and green.
• Damage along the visual pathway. Occasionally, a glitch along the visual signal pathway will interfere with the process of signal transmission. Sometimes the problem could be with the optic nerve that transmits the signal. At other times, however, the snag might be a neurological one that happens in the visual cortex of the brain.
  
  There are many different things that could potentially cause this damage, and, as it turns out, alcohol might be one of them. Let’s take a closer look!

Alcohol and Vision: A Closer Look 

Alcohol can mess with the body in many ways we hear about often — damaging the liver, affecting the heart, causing brain damage, and so on. But did you know it can do a number on our vision? We’re not just talking about the blurry double-vision we get after a couple of margaritas or the infamous “beer goggles” that lead to questionable choices and embarrassing morning-after scenarios.

• Drinking causes hypoxia, which affects the eyes. Hypoxia means “low oxygen” — and that’s exactly what it is. Drinking too much over time deprives parts of the body of oxygen, and the eyes are no exception. (While this condition is reversible, if we really overdo it, it could cause permanent damage and might even be fatal.)
• Hypoxia can lead to optic neuropathy. Optic neuropathy is vision impairment due to changes in the brain — and yes, alcohol can cause it (especially if we also smoke). Over time, depriving the optic nerve and retina of oxygen can damage these delicate structures, potentially impairing vision. A study in Alcohol and Alcoholism sheds light on how the damage happens by showing that repeated ethanol exposure caused retina damage in rats. Specifically, alcohol-related damage was shown to affect the optic nerve, which plays a crucial role in transmitting visual information from the eyes to the brain. 

However, there’s an additional pathway through which alcohol damages the eyes — one that is directly related to color vision. Let’s take a closer look at what this means for the way alcohol can reduce your ability to see what colors look like.

Alcohol and Color Vision: Starving the Visual Cortex

Studies show that alcohol can reduce your ability to distinguish between two colors. A study of young adults that examined the link between color vision and alcohol consumption found that even low to moderate alcohol intake took a toll on the ability to discriminate between colors and perform color arrangement tasks.

Authors suggest a mechanism for how this happens. There are specific cells in the retina that correspond to neurons in the visual cortex — when they’re activated by light of a certain wavelength, they send the message to their designated cortex “corner.” The neurons in the visual cortex require a lot of energy. Alcohol can throw a wrench in the distribution of nutrients throughout our body by reducing metabolic capacity. The result? Those hard-working neuron regions go underserved and lack the resources they need to perform at their best.

What Colors Does Alcohol Affect?

Does alcohol affect our ability to tell the difference between specific colors? It appears so!

“Drowning Out” Blue and Yellow

When it comes to colors, alcohol can have a particularly strong effect on blue and yellow. A study that followed 136 people with 16 in treatment for alcohol use disorder (AUD) showed that many had trouble distinguishing between different colors. Blue and yellow seemed to be the ones that were most affected, probably due to the higher density of nerve cells corresponding to those colors in the brain.

Others suggest similar results. An article on “tritanopia” — blue-yellow color blindness — suggests that one of the reasons for the condition is alcohol exposure. Unlike the more familiar red-and-green color blindness, genetic tritanopia is actually pretty rare, affecting only about 1 in every 10,000 people. So if we have it, it’s more likely that we acquired it through lifestyle factors (such as drinking) rather than inherited it.

There are a few other reasons tritanopia can develop:

• Age. As we get older, our eye lens becomes less transparent, leading certain colors to be more difficult to distinguish. Blue and yellow can be among them. Cataracts and macular degeneration that comes with age could also be responsible for blue and yellow color vision difficulties.
• Organic solvent exposure. A link was discovered between organic solvent exposure and color vision, primarily on the blue-yellow range.
• Injury. Finally, injury to the front or back of the head can “knock” blue and yellow out of our sight! (Well, the reality isn’t quite so dramatic — but you get the picture.)

Thankfully, it’s also a bit less disruptive to everyday life than the red-and-green variety. (After all, not being able to see the contrast in colors in that IKEA sign we mentioned at the beginning isn’t quite as much of a problem as not distinguishing the colors of a traffic light.) 

A Color-Fading Future

At the same time, it looks like blue and yellow might just be the beginning. The study that found blue and yellow to be the main colors affected by alcohol consumption suggested that red and green could also be affected with time. The authors suggest that losing our ability to spot the difference between blue and yellow could be the first sign in a wider-spread degeneration in our ability to see colors due to excessive drinking.

Is It Reversible?

While alcohol can reduce our ability to distinguish between two colors, the good news is that the problem is often reversible! If we cut back on our drinking (and follow some other vision-friendly lifestyle tips discussed later), we can often get those vibrant colors back in our lives. (Yay!)

Spotting the Symptoms

What can we do if we suspect that our color vision is taking a hit due to alcohol consumption? An eye specialist will likely have us take a “color blind test.” Developed by Japanese ophthalmologist Shinobu Ishihara, the test is simple yet effective: it consists of circular “plates” of colored dots with numbers “hidden” among them as dots of a different color. 

For example, to test for blue and yellow color blindness, we might be asked to look at a plate of yellow circles of various shapes and shades. Inside the array, some of the dots — strategically placed to form the shape of a number — would be blue. Can’t see the number within the dots? You might have tritanopia.

While the Ishihara test works surprisingly well, if our situation calls for a more detailed investigation, we might take the Farnsworth-Munsell 100 Hue Test. This one feels a bit like a board game and is based on small disks of various hues that we are asked to arrange in four horizontal trays to form a continuous sequence ranging from dark to light. If we have trouble distinguishing between the hue differences within a certain color — for example, yellow or blue — the difficulty might indicate a problem with our color vision.

Don’t want to wait for an appointment to find out if there’s trouble brewing? There are also plenty of online color vision tests available, though, of course, they might not be quite as accurate.

And, of course, if we’re noticing other signs of excessive drinking, the problem isn’t one we should ignore. Alcohol-related damage to the body (including the eyes) tends to get worse over time, so it’s better to stop the problem in its tracks! 

Keep Your Vision Sharp

Is there anything we can do to keep the lovely shades of yellow and blue (as well as all the other colors of the rainbow) in our lives? You bet!

• Watch your alcohol intake. First and foremost, take a closer look at your alcohol habits and see if anything needs changing. Cutting back or quitting altogether can help further color vision impairment while also improving your life in myriad ways. (Want a preview? Here are just a few benefits coming your way: better sleep, radiant skin, weight loss, a sharper mind, and lower risk of cardiovascular disease and many types of cancers.)
• Nourish your eyes. Remember how mom always told you to eat those carrots? She was right! In addition to orange foods (such as carrots and pumpkin, both of which are rich in vitamin A), make sure to eat a diet rich in antioxidants, omega-3 fatty acids (found in salmon, olive oil, and avocados), and vitamins C and E. All of these nutrients are known to support healthy vision.
• Watch your vision habits. Another piece of useful advice you might remember from childhood? Avoid eye strain caused by reading in the dark (comic books under the covers, anyone?) or in a moving vehicle. 
• See your eye doctor. Make sure to stay on top of your vision health by seeing an eye specialist when you need to. If you notice that something might be amiss, don’t delay — many eye issues only get worse with time, so you want to catch any problems early, before they get worse.

Remember, preventing problems is always better than solving them after they develop. So, even if you’re not having trouble telling colors apart right now, it’s never too early to get proactive about your eye health!

Getting a Clear Picture

While color vision might not be on top of your list when it comes to alcohol-related concerns, in the end it’s an important part of our daily experience. Let’s do everything we can to keep the world in front of us sharp and colorful!