Why can’t eyesight fix itself? Bones can mend, blood vessels can repair after a bruise…what’s so special about lenses that they can only get worse?


How is it possible to have bad eyesight at 21 for example, if the body is at one of its most effective years, health wise? How can the lens become out of focus so fast?

Edit: Hoooooly moly that’s a lot of stuff after I went to sleep. Much thanks y’all for the great answers.

In: 4262

It can. If your eye is damaged, it will at least try to repair itself. Lenses are usually left foggy afterward, as scar tissue does not play nice with the optically smooth surface needed for a good lens.

If you’re referring to nearsightedness/farsightedness, they happen because your body makes the eye the wrong shape. It’s exactly how your body thinks it’s supposed to be, so it doesn’t fix it.

your eye is more complicated and delicate than those other body parts by comparison. A bone is just a bunch of the same material in a line. Blood same thing. Your Eye is several pieces arranged into a bowl that is capable of capturing light and encoding it. As our cells divide, stuff that’s essentially the same material just spreads out. But because of the complexity of the eye, the irregular nature of cell division progressively deforms the complex machine. That’s why everyone’s eyesight gets worse as they get old. Now, you ask why the eye can’t heal itself. But the way the body heals itself is through cell division. It’s just that this tool for self-healing is particularly ill suited to healing an eye for the reason above.

Tagging along – Are we able to reverse myopic naturally?

Healing is basically the body making more of the damaged thing. When you get a paper cut, your body makes extra skin and sticks it in there. Same thing when you break a bone. There are some things the body can’t make more of, or it’s so precise that just lumping extra material in doesn’t work. And it’s possible to have permanent damage if enough is gone or it’s killed in a special way.

Eyesight has to do with the flexibility of the lens, a plastic-y thing about the size and shape of an m&m. Muscles are attached to the edges to pull it into the right shape. Over time, the lens gets less flexible. Pulling harder would risk breaking it. The body can’t “repair” it because it’s not broken. And putting more lens material on it only make vision worse, because then it’s thicker. Imagine the difference when looking through a cup made of thin glass, versus a cup made of thick glass.

Bad eyesight becoming so common is because of evolution. In the 1700s, it was rare for someone to have less than perfect vision, even as they got older. But because we’re no longer looking out for bears or hunting for rabbits, we don’t automatically die if we get near-sighted. As a result, people with bad eyes live long enough to have kids.

Things that can’t heal themselves: teeth, bone coating (like inside the knee), cut tendons, cut nerves. That’s why fake teeth, knee replacements, tendon transplants, and paralysis are so common.

Things that can heal, but are bad at healing: nerves, kidneys. Which is partially why so many people need kidney transplants.

There are limits to how much the body can heal itself from certain injuries. But your eyes getting worse is not an injury or something, its just an effect of the aging process. Certain parts of your body can just degrade over time. Many factors go into this, nutrition, geographical environment, genetics, etc. So everybody’s eyes degrade at different rates depending. Like, if you get a scratch on your eye like from dirt or debris getting in your eye, that part can heal itself over time. But again that is considered an injury, not a natural result of time.

Your eyesight *can* improve itself on its own, long term. I was severely nearsighted as a child, coke-bottle style, but we tend to grow more farsighted as we age (things stiffen). By my mid-20s my prescription was roughly half of what it was originally. In my early 40s, I officially crossed the line and switched from being slightly nearsighted to being slightly farsighted. These days I wear progressive lenses (equivalent to trifocals, but with a smooth transition between the distances), but not very powerful ones.

The astigmatisms, however, have never budged.

Edit: because I do know the difference between where and wear.


I had some untreated hyperthyroidism. One of the symptoms is they eyes get deformed (usually bulging although mine were not). My sight was getting progressively worse. Once I had the condition treated, my eye sight has actually improved a little bit.

I believe structural eye problems are tough for your body to repair as most of the repair/healing functions add or remove tissue and the eye pretty much needs to stay in ballence to properly focus. But, if it is an external force that is causing the issue (such as extra pressure deforming the eye) and that issue is resolved, your eye can bounce back

Lenses are like eye teeth. You have to look after them because they get worse over time no matter what you do. With teeth you avoid sugar and brush etc. With lenses they degrade with exposure to UV and your eye muscles generally get weaker as you get older too. Wear sun glasses kids!

Not all things in our bodies are equal. Our skin, our bones, our muscles, our organs, they all heal with different levels of efficiency to different kinds of injuries or abnormalities. The eyes are very specific body parts, we don’t have anything else like them in our bodies, and their tissues are also very particular. I for one think that they’re much more resilient than we give them credit for, because we consider them very sensitive body parts but the fact of the matter is that eyes often heal from very brutal things, be it all sorts of chopping and lasering with surgery or injury from foreign objects, car crashes, environmental factors like extreme conditons etc. There’s all sorts of ways temporary blindness can be caused from which the eyes recover which I honestly find remarkable.

That being said there’s just a few limits to what our bodies can do. Most people are born with deficiencies, things that are not quite right be it bad eyes, bad teeth, bad airways, bad joints, bad immune systems, bad organs and all sorts of other things that are not quite right which are like this from birth but show themselves throughout our lives and not always from the beginning.

I wish scarring could be corrected. I have scarring on my central line of vision causing me to go blind.. Nothing I can do about it except hope I don’t go completely blind!