Why Does Alcohol Consumption Cause Blurred Vision?

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The blurring of vision from alcohol consumption is caused by the slowed transmission of signals between neurons, the affected muscles of the iris, and the difficulty to distinguish between contrasting images.

Imagine a night of mirth and celebration. Everyone is laughing, passing around plates of food and sipping on their drinks. After one too many drinks, however, you get up to walk across the room, but your vision is blurry from all the alcohol swimming in your blood.  Anyone who has ever consumed more than a few drinks knows the all too familiar blurring of vision due to alcohol consumption, but why does this happen?

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Alcohol’s Effect On Vision

Alcohol can affect our vision in a number of ways, both in the short and long term. While regular heavy drinking can cause permanent damage in the long run, even occasional drinking affects the vision, albeit temporarily.

The short-term effects of alcohol on our vision include the blurring of vision, double vision, dryness of the eyes, twitching of the eyes, migraines etc. These are temporary, and usually go away completely a few hours after the cessation of drinking. They don’t pose any serious long-term threats to the eyes and are considered normal.

However, long-term, heavy drinking can pose some serious threats to our vision. It can increase the chances of developing age-related macular degeneration. While this usually occurs in older people, it can be spurred on by excessive smoking and alcohol consumption. Heavy drinking also increases the chances of cataract formation, and the risk of optic neuropathy, or vision loss. Excessive drinking also affects the body’s absorption of vitamins, which can adversely affect the eyes. Depending on which vitamin is lacking, it can lead to night blindness, thinning of the cornea, etc. In pregnant women, it also risks compromising the vision of the fetus.

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Also Read: Why Do We Make Poor Decisions When We Are Drunk?

Blurring Of Vision

For anyone who drinks occasionally, blurred vision is the most common side effects, and probably one of the first few signs of getting drunk.

As we all know, while our eyes do the “looking”, our brain does the “seeing”. This means that our eyes look at the image before us and send the information to the brain. The brain then deciphers the information, and we “see” whatever is in front of us. Therefore, the coordination between our brain and eyes is essential.

Alcohol affects our body in many ways, some of which are responsible for the effect on our vision. The transmission of signals between our neurons, via neurotransmitters, gets slowed down, as a result of alcohol consumption. This affects the coordination between the brain and the eyes.

Another thing that gets affected by alcohol are the muscles of the iris. These muscles control the movement of our lens, which is essential for focusing on objects in front of us. Since this muscle movement is affected, we take longer to focus on objects. One study also showed that alcohol consumption can affect our ability to distinguish between contrasting images, which also contributes to blurry vision.

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How Much Can A Person Drink Safely?

There is no fixed amount or threshold beyond which these symptoms will start to show. It varies from person to person and is affected by age and gender. Women generally tend to have a lower tolerance, which means that they will start exhibiting these symptoms sooner than men. However, this is not a universal rule. Age also reduces a person’s tolerance for alcohol, so these symptoms may appear earlier.

However, it should be kept in mind that while some of these symptoms are not harmful in general, they can prove to be a hindrance while driving. Alcohol slows down a person’s reaction time, so one should never drive while drunk.

The occasional consumption of alcohol is not very detrimental to health, but excessive drinking can have very serious repercussions, not just on vision, but on many other parts of the body as well.

Also Read: Why Does Alcohol Affect Women More Than Men?

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References (click to expand)
  1. What alcohol really does to your eyesight | The Independent. The Independent
  2. Karimi, S., Arabi, A., & Shahraki, T. (2021, April 29). Alcohol and the Eye. Journal of Ophthalmic and Vision Research. Knowledge E.
  3. What is the Effect of Alcohol on the Eye? - CooperVision. CooperVision, Inc.
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About the Author

Mahak Jalan has a BSc degree in Zoology from Mumbai University in India. She loves animals, books and biology. She has a general assumption that everyone shares her enthusiasm about the human body! An introvert by nature, she finds solace in music and writing.