We’re likely far from the only source you’ve run across with a warning against heavy drinking. Excess alcohol consumption is rough on a human body from end to end. Essentially every organ can be damaged by chronic alcohol abuse, but as a site devoted to vision health, we’ll pay particular attention to the effects it can have on your eyes.
Many harmful lifestyle choices do negatively impact the eyes. Both smoking and unhealthy body weight can have surprisingly serious consequences for your visual health, even if they’re not immediately apparent. Add drinking to the list. While moderate consumption isn’t going to blind you, more focused boozing can put your eyes in a world of hurt.
Perhaps the most famous alcohol-related visual disorder has nothing to do with what we normally think of as alcohol. Ethanol is the compound normally present in beer, wine, and spirits. Its effects are well-known, and while they can be severe, they pale in comparison to its chemical brother, methanol. Also called wood alcohol, methanol may seem quite similar to ethanol at first blush. However, ingesting it in any quantity can cause massive damage to the nervous system.
Blindness is a well-known consequence. The toxins formed by the body’s processing of methanol quickly attack the optic nerve and can irreparably damage it if present in high enough concentrations. Fortunately, methanol isn’t likely to be present in any professionally produced spirits. When it does make a deadly appearance in a beverage, it largely does so as a result of mistakes made during the distillation process.
Alcohol and Cataracts
Heavy drinking may also figure into one of the world’s leading causes of preventable blindness. Cataracts are incredibly common among older individuals and occur after years of damage causes proteins in the eye to turn opaque. Once they do so, they interfere with light entering the eye, causing a scattering effect and often resulting in decreased visual acuity, difficulty with high-glare conditions, and astigmatism, or blurry vision.
Recent work by a team from Boston University found that heavy consumption of alcohol (more than two drinks per day) seriously increased study subject’s risk of having cataract surgery. Before you bust out the teetotaling pitchforks though, consider this – abstinence had a similar effect. Moderate consumption of alcohol, for whatever reason, seemed to correlate to reduced odds of surgery.
As with smoking, heavy alcohol use can deal lasting damage to the optic nerve, an essential link between the eyes and the brain. While ethanol itself is unlikely to directly attack the nerve, it does vastly increase an individual’s chances of encountering optic neuropathy.
If this does happen, vision can degrade quickly and seriously. A decline in color vision is among the first symptoms. Called dyschromatopsia, the condition often results in a dulled perception of colors, most notably red. General reductions in visual acuity usually follow, with rare cases progressing to total blindness.
Alcohol abuse also correlates closely with malnutrition. While calorie-packed, alcohol doesn’t contain much in the way of essential nutrients. So while heavy drinkers may feel full, they’re likely not getting what they need in terms of vitamins and other hard-to-grab nutrients. The damage that alcohol can do to internal organs also interferes with the body’s normal absorption of what nutrients it can obtain. The result: malnutrition, and as we’ve often said, the eyes feel that shortfall dearly.
Vitamin A deficiency can cause night blindness as the eye loses its ability to manufacture key pigments. Serious cases can even lead to chronic dry eye and lasting damage to the eye as a whole. A dearth of zinc can up a drinker’s odds of contracting certain types of cataracts, doubly so given that heavy alcohol use already exacerbates the condition. The list goes on and on. Even a normal diet often misses out on some key nutrients, hence the existence of various vision supplements. But the shortages caused by alcoholism are often far beyond such easy repair.
Alcohol and AMD
The role it plays isn’t clearly understood, but alcohol is also a contributing factor to age-related macular degeneration, or AMD. Common among older Americans, AMD slowly erodes central vision, and can lead to a state of practical blindness. A range of causes are known to contribute to AMD – smoking, excess exposure to sunlight, and yes, immoderate drinking can all potentially increase a person’s risk of running into this serious degenerative condition.
Again, the exact mechanism behind this effect isn’t fully understood, but it may relate to the general injury that alcohol can cause to the brain. Oxidative stress, a measure of a certain type of chemical damage dealt to tissues in the body, appears to be a one of the factors behind the progression of AMD. Alcohol is known to cause oxidative brain damage and some theories suggest that the same action could directly affect drinkers’ retinas, eventually resulting in the symptoms of AMD.
How Much is Too Much?
We can’t offer much of an opinion on how much alcohol is excessive in other parts of a person’s life, but as far as eye health is concerned, there is a sharp divide between the effects of so called “social drinking” and actual alcoholism. While there’s no exact magic number, most studies do have a rough cutoff between the two at 2-3 drinks per day. If you find yourself consistently exceeding that limit, then it’s time to evaluate the habit. For your eyes’ sake, and for your own.