How Successfully Can Lasik Fix Farsightedness?
Lasik is well known to treat nearsightedness. In fact, treating nearsightedness with lasik is so common, that typically whenever anyone talks about lasik and its results, they are probably talking about nearsighted lasik. That is pretty much the default. And it’s partly because lasik works really well to correct nearsightedness.
But how does lasik perform for farsightedness? It can be a little harder to find this information. Fortunately, you made it to the right spot.
Generally, lasik still can work well to fix farsightedness. However, it doesn’t work as well as lasik does for nearsightedness. Expect the treatment to be a little bit less accurate and also expect some of the treatment to wear off over time.
Let’s dive in! But first, let’s review farsightedness and see just how lasik works to fix it.
There are 3 main categories of prescription
- Nearsighted - meaning you can see well up close without glasses but need glasses to see off in the distance
- Farsighted - you can see well or better off in the distance without glasses than you can see up close
- Astigmatism - can go along with both nearsighted and farsighted prescriptions. Causes things to be more blurry at all distances. Check out The Simple Explanation of What Is Astigmatism to learn more about it.
Also check out The Key Difference Between Nearsighted Vs Farsighted Vision to learn more about the differences.
Often lumped into farsightedness is the loss of reading vision called Presbyopia. Presbyopia is when the natural lens inside our eye becomes weak and can no longer focus up close. This starts to occur in our forties.
While technically not a “true” prescription error, presbyopia still makes it harder to read up close similar to farsightedness.
Presbyopia, however, affects farsighted individuals MORE.
In addition to being able to focus up close, this natural lens is also able to focus through farsighted prescriptions. Because of this, many farsighted individuals may not even know they are farsighted until this lens has trouble focusing through their prescription.
But this natural lens only has so much focusing ability.
For farsighted individuals to look up close, some of the focusing reserve of the natural lens is “used up” focusing through the farsighted prescription before being able to focus up close.
This means farsighted individuals typically have trouble reading up close at an earlier age then someone who has perfect vision.
As the presbyopia gets worse, this natural lens becomes unable to focus through the farsighted prescription causing distance vision to become blurry as well.
This loss of reading vision with or without combined with the loss of distance vision is what prompts many farsighted individuals to look into lasik to see about getting out of reading glasses.
Using Lasik To Treat Farsightedness
Now that we’ve gotten that important background out of the way, let’s see how lasik can fix it.
Farsighted individuals have an eye prescription that is too weak. When you use +2.00 or +3.00 reading glasses to see, you are ADDING more prescription to the eye (note the positive number in front of the reading glasses prescription). When your natural lens changes shape to focus through your farsighted prescription, it is adding more prescription to your eye to bring things into focus.
To treat farsighted prescriptions, we want to make the eye prescription stronger.
Lasik treats the cornea, which also happens to be the primary spot in the eye which focuses light. As a general rule, the steeper the cornea is, the stronger the power and ability for the cornea to focus light.
So to treat farsighted prescriptions, lasik works to make the cornea steeper.
But lasik is only capable of removing microns of cornea tissue with each laser pulse. It CAN’T add more cornea to steepen things up.
So to treat farsighted treatments, instead the lasik laser treats in more of a donut pattern around the center of the cornea. This causes the center of the cornea to become steeper and thus more powerful. Getting rid of the farsighted prescription.
Difference between farsighted lasik treatment and nearsighted lasik treatment. Treated area in red. Note black line showing steeper cornea after farsighted lasik treatment; cornea graphic courtesy of Jmarchn, CC BY-SA 3.0, via Wikimedia Commons
How much can farsighted lasik treat
Farsighted lasik CAN’T treat as much prescription as nearsighted lasik.
The current generation of lasik lasers within the U.S. can treat up to +6.00 of farsighted prescription. Fortunately, that is still quite a bit.
Additional note on correcting reading vision
If you are above the ages of 40-45 and looking to get out of reading glasses, than farsighted lasik MUST be combined with a technique called monovision. In monovision, one eye is corrected for distance vision, the other eye is corrected for up close, reading vision.
This is necessary because correcting your farsighted prescription with lasik doesn’t fix the weak natural lens in presbyopia. So simply correcting your farsighted prescription will eliminate that and give you good distance vision, but your lens still won’t be able to focus up close and allow you to read.
Learn more at Everything To Know About Monovision Lasik.
Already have good distance vision? Then you may only need lasik on one eye to focus it for up close.
Success Of Farsighted Lasik
The accuracy of the treatment is high, but not quite as high as with nearsighted lasik.
With farsighted treatments, about 70-75% of individuals will have full 20/20 vision without glasses. Those are good numbers, but they aren’t quite as good as the 90-95% achieved with nearsighted lasik.
Farsighted lasik just doesn’t have quite as high of accuracy. The more farsighted prescription you need treated, the less accurate the procedure can become.
The other big consideration with farsighted treatments is that they tend to “wear off” more than nearsighted lasik treatments.
The donut shape of the farsighted treatment is successful at making the center of the cornea steeper, but it creates an usual curve gradient on the cornea. The cornea becomes flatter at the edges and steeper in the center.
In general, our cornea “prefers” smoother gradients. Because of this, the skin on the surface of our eye, called epithelium, can become a bit thicker where the lasik treatment happened in order to smooth the cornea out more.
This process can cause some of the farsighted prescription to return within the first year - which can make it a little more difficult to see things up close.
But that isn’t the only thing. There is another issue at play, technically unrelated to the actual lasik treatment.
Natural changes in the eye
As we get older, our eye can continue to change.
We already talked about one part of it, presbyopia - where we lose the ability to read up close.
But in our forties and beyond, the prescription of the eye typically slowly changes as well. Our eye becomes MORE farsighted the older we get.
It’s a small amount, but it becomes significant over time.
And again, as some of the farsighted prescription returns, it becomes more and more challenging to see up close.
Between the early adjustment of the eye to the lasik procedure as well as changes to happen as we get older, many will notice that close to +1.00 of prescription can wear off over 5 years. Advancements in lasik lasers may have improved that, but long term data is necessary to assess for sure.
So while lasik can work to eliminate the bulk of the farsighted prescription, you can expect that at some point in the future some of that prescription will return and the need for glasses returns.
Lasik can in fact be used to fix farsightedness. It works well, but just not AS well as what lasik does for nearsightedness. In general, expect the accuracy to be a little less. But more importantly, don’t expect to be out of glasses forever. Over time, the effect of the treatment can wear off making you need glasses again.
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