Why can’t laser eye surgery cure blindness? Eli5
I’ve been told I’ve got diabetic retinopathy and it’s getting worse. They mentioned potential ‘sudden vision loss’ and I went on a wild internet search and ended up here. Can someone tell me how laser eye surgery can make eyes see perfectly when they usually need glasses for severe vision impairment but can’t do anything for full vision loss? Please. Like I’m five. Thanks!
In: Biology
It depends on what the issue is with your vision.
Normal Lasik just reshapes the cornea to correct for issues with the lens of the eye. Basically, the lens bends the light wrong, so we bend it a little differently before it gets to the lens to _now_ the final product is in focus.
It can’t correct for other issues in the eye that might cause vision problems or blindness. If you have retinopathy – issue with the retina itself – Lasik can’t help you.
If you can’t see you can’t see. A laser can’t fix that.
Laser eye surgery fixes blurry vision, like a camera that has issues with the lens being out of focus. Fixing a lens doesn’t help if the camera sensor doesn’t work.
> Why can’t laser eye surgery cure blindness?
Because it’s not magic. It just adjusts the focus point of the lens system inside the eye, it can’t grow back stuff that is dying off. You can keep polishing the lens of a camera with a broken sensor, it just becomes a slightly shinier paperweight.
Your eye has various different parts. The cornea is a clear covering, the lens focuses the light, the iris adjusts how much light comes in and the retina is the cells at the back which have a blood supply and nerves to transmit the light signals to your brain.
Blindness can be caused by issues with any of those. If the lens is misshapen, we can correct it with glasses or by using a laser to reshape it. This changes how the light is focused so you can see more clearly.
Things like cataracts are cloudiness of the lens, and a treatment can remove the cloudy parts so you can see again.
Diabetic retinopathy is a problem with the blood supply to the retina. This damages the cells which receive the light. No tinkering with glasses, the cornea or lens can bring back dead or dying cells at the back of your eye.
There are many conditions that affect the retina, including things like macular degeneration, where the central part of the retina is damaged and can’t receive light signals any more. There is limited treatment for retinal issues.
I had a bleed in my retina on one eye, it caused a separation of the top layer of the cells from the underneath. I now have a large blind spot in the centre of my vision and there is nothing anyone can do about it. I feel your pain and your worry about it. It sucks.
There are lots of different kinds of vision issues. And they can be solved by different things. The most common issue is that the lens in the eye is not shaped quite right. Some are more convex then they should and some are less convex. This can easily be corrected with correcting glasses, contact lenses or a laser can change the shape of the corona in front of the lens. Some people who have extremely bad vision from this so that they are legally blind because they can not use their eyes can get corrective laser eye surgery to get some use for their eyes, although when it is that bad they often need glasses anyway.
What you are suffering from is not in the lens or any of the parts of the eye that a regular laser eye surgeon operates on. You have issues with your retina, the part in the back of your eye. It is a different part of the organ. You have to look at different types of treatments because you have a different condition in a different part of your eye then everyone who gets corrective laser surgery.
Coincidentally some of the treatments for diabetic retinopathy does involve laser surgery. But lasers are used in lots of different medical treatments in different parts of the body. This is a different laser then the one which is used in corrective eye surgery because it targets a different part of the eye and does a different thing to it. Also note that while some people can get their sight improved in this way you might not. All instances of the disease is different and can not be treated the same way. This is something your doctor needs to prescribe with the help of a surgeon.
It depends, but potentially in your case (you should speak to your ophthalmologist). Normally people get laser eye surgery to help focus the light better, but in your case chronic high blood sugar has damaged the blood vessels in your eye. There are different laser surgeries that can treat the symptoms of this, but you will also need to control your blood sugar (the underlying cause). This isn’t something you will get clear answers for on the internet.
More ELI5 than some of the other answers:
The part of your eye that is broken is not the part of your eye that kind of surgery can fix. The kind of surgery that makes people not need glasses fixes a part of the eye that is very close to the outside. The part of your eye that is broken is deep inside.
There is another kind of laser surgery that helps with the deeper part. It stops bleeding deep in the eye, which can help some people with diabetic vision issues see (I’ve taken my father-in-law for this kind of surgery twice). As you can imagine, if you had a lot of blood inside your eye, you’d have trouble seeing, because blood isn’t clear. But even that kind of surgery doesn’t completely fix the problem, it just stops the bleeding, which helps the most noticeable symptom.
Laser eye surgery is “just” reshaping the cornea on the front of the eye to change the lens geometry. Injuries and illnesses of the retina or optical nerve are “further up the line” and are related to the connection to the brain.
Okay, imagine your eyes are like windows. Sometimes, things like diabetic retinopathy can make those windows blurry or damaged. Laser eye surgery is like fixing a small crack in the window to make it clearer, but it can’t fix it if the window is completely broken. So, while laser eye surgery can help improve vision for some problems, it can’t make someone see perfectly if they’ve lost their vision completely. It’s like trying to fix a really big hole in the window – sometimes it’s just too much for the surgery to fix.
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