June 26, 2023 | Lasik

Known Lasik Side Effects You Can Have

By Barrett Eubanks, M.D.

Known Lasik Side Effects You Can Have

Lasik has come a long way since it was introduced over two decades ago. And while it was revolutionary in being able to permanently correct vision, it also came with some extra unwanted side effects.

But here’s the thing. Lasik has evolved. Just like how every other piece of technology has evolved over the past two decades. Can you believe that we didn’t have any smartphones 20 years ago? And so trying to compare Nokia phones from days of yore to the latest iPhone 14 Pro just simply doesn’t make any sense.

A similar concept applies to lasik. Lasik isn’t the same procedure that it was 20 years ago. It’s gotten better. As it’s gotten better, sides effects from lasik have improved.

But side effects haven’t been eliminated completely. And even despite the improvements in lasik, you can experience some unwanted side effects. Side effects that can leave about 1% dissatisfied after lasik.

So let’s focus on what you can experience with today’s lasik using modern lasers.

For the purpose of this article, we will be going over side effects. These can be defined as symptoms everyone may have to some degree. This is in contrast to actual complications which are unplanned events that occur during of after treatment. To learn more about lasik complications and round out your knowledge about lasik, be sure to visit Must Know Lasik Complications in 2023. Is Lasik Safe?

To best categorize the side effects, let’s sort them out by duration; starting with the ones that don’t last long after lasik to the ones that last much longer.

Very Short Term Side Effects

Immediately after lasik, you WILL have some side effects. These side effects happen to everyone, but some may notice them more than others (a theme we’ll see with all the side effects of lasik).

Scratch On The Eye

On the surface of our cornea is a smooth layer of cells called the epithelium. These cells serve as the “skin" of our cornea to protect it. Just like on our skin, if there is a break or a scratch in this layer, it will be painful. And in fact, since the cornea is the most sensitive part of the body, you will have a lot more pain from a cornea scratch than a scratch on your skin.

Creating a lasik flap WILL create a break or scratch through this layer. That’s just the nature of creating a corneal flap.

This break or scratch will lead to

  • discomfort or pain
  • sensitivity to light
  • feeling like there is something in the eye
  • and more

Everyone after lasik will have this to some degree. Fortunately, this scratch heals up very quickly. It only takes about 2-6 hours for that initial pain from lasik to go away. And typically surgeons will tell you to take a nap to “fast-forward" through this discomfort.

Some people can get a larger scratch on the eye. They may start out with a weaker epithelium layer. That combined with the tiny surgery instruments used during lasik can lead to a larger scratch or abrasion. This can take longer to heal up.

Red Spots or Bleeding On Eye

The white part of our eye is called the conjunctiva. Similar to anywhere else on our body, the conjunctiva has blood vessels that can break and can become bruised. (and in fact it may be easier to bruise the conjunctiva since it doesn’t provide a whole lot of protection for those blood vessels).

When the conjunctiva becomes bruised, it becomes pretty obvious. Since the conjunctiva is transparent, the broken blood vessels make the eye appear bright red. The medical term for this is a subconjunctival hemorrhage.

This can happen during lasik. Particularly during the part of the lasik procedure which creates the lasik flap. In order to ensure that the lasik flap is properly created, the laser will actually suction onto the surface of the eye.

This suction can squeeze the blood vessels in the conjunctiva and cause some of them to break. Causing your eye to be bright red.

Fortunately, this bleeding has zero impact on the lasik treatment. It just doesn’t look very pretty. Gradually, over the first week after lasik, this blood thins and resolves.

Learn more about this side effect at What Causes Blood In Eye After Lasik?

Eyelid Swelling

After lasik, you can have a small amount of swelling within the eyelids. Although typically it’s pretty small after lasik.

There are two main reasons eyelid swelling can develop after lasik.

  • The eyelid holder used during lasik can create a small amount of “trauma" to the eyelid. So the eyelid swells as an injury response.
  • The scratch on the cornea is “trauma" to the cornea. So extra inflammation builds up on the surface of the eye as a response to this trauma. The conjunctiva is actually connected to your eyelids. So, blood vessels in both the conjunctiva and eyelid can respond to this injury and cause a little bit more swelling.

Typically it doesn’t take long for this swelling to resolve, but read more about how to treat this eyelid swelling at Here’s How To Get Rid Of Eyelid Swelling After Lasik

Side Effects For Months Out

Here are some of the bigger well known side effects from lasik. While the previously discussed side effects disappear pretty quickly after lasik, these can last for much longer.

Dry Eye

Most people will notice an increase in dry eye after lasik. Lasik WILL cause a short-term dry eye.

As talked about above, the cornea is the most sensitive structure in our body. How does it get to be so sensitive? By having a lot of nerves.

These nerves do complex things. The short version is that these nerves regulate the natural layer of tears on the surface of our eye. Having a layer of tears is important to keep our eye from drying out and keeping our vision clear.

Creating a lasik flap WILL disrupt these nerves. And it will take some time for these nerves to regenerate. Until those nerves are restored, the eye can’t do as good of job regulating the tear film. We make less tears and our tears don’t stick around on our eye as well as before.

In summary: Our eye dries out more.

This dry eye heals up differently for everyone. Some may only notice it for a few weeks out after lasik. About 60% will still have increased dry eye at one month. This number drops to 25% at 3 months and 20% at 6 months. By the one year mark, almost everyone is back to normal.

Learn more at Exactly How Long Does Dry Eye Last After Lasik including a very rare exception that can cause bad dry eye that lasts longer.

It’s important to treat dry eye after lasik to speed resolution and keep it from getting worse. The first step for all lasik patients is to start frequent preservative free artificial tears. Visit These Are The Best Eye Drops After Lasik for a comparison of the different types.

Halos, Glare, Starbursts

These all fall into the category of “unwanted vision problems". This can be annoying, blur vision, or add trouble driving at night.

How does lasik create these issues?

The shape of our cornea contributes significantly to determine the prescription of our eye. Lasik takes advantage of that fact to correct our prescription by changing the shape of our cornea.

However, lasik doesn’t treat the entire cornea. Lasik only treats the center.

Flattening of cornea from lasik treatment
Flattening of cornea from lasik treatment. Lasik flap is in blue, cornea removed with treatment is in red; cornea graphic courtesy of Jmarchn, CC BY-SA 3.0, via Wikimedia Commons

What we are left with is a cornea that is a different shape in the middle compared to the edges. Light will actually focus at a different spot depending on whether it passes through the edges of our cornea vs whether it passes through the center.

This mismatch in focus (creating something known as spherical aberration) is largely responsible for the development of halos after lasik.

But other things can happen to create other problems with vision. For example, if the lasik treatment isn’t centered very well on your vision, there will be more alterations in the focus of light creating starbursts. This becomes even more important when treating farsighted prescriptions with lasik.

But remember how lasik has evolved over the past two decades? This is one of the areas that has seen dramatic improvement.

Modern Lasers

Modern lasers treat our eyes much better; resulting in a smoother cornea. As such, modern lasik has much less issues with halos, glare, and starburst.

In fact, you are more likely to have LESS issues with halos, glare and starbursts AFTER lasik than before with the modern lasik lasers. This also equates to BETTER night driving vision AFTER lasik.

Roughly 40% may notice an increase in halos and other symptoms at 3 months. But these are typically mild and not bothersome. By the one year mark, these symptoms have typically returned to pre-op levels or better as the brain adapts to the changes.

Only about 4% will have bothersome symptoms after lasik; But that is even that is down from 12% before surgery. There is a greater chance that today’s lasik will actually improve your significant halos and glare rather than make it worse.

This is a large contrast compared to older lasers where roughly 25% developed significantly worse halos, glare and starbursts after lasik.

In addition, advanced laser technologies such as topography-guided lasik treatments have the ability to smooth out any existing distortions or aberrations in our cornea to further reduce and / or eliminate pre-existing halos, glare and starbursts and potentially even improve vision beyond what can be done with glasses or contact lenses.

This is one area where today’s lasik is vastly different than the past.

Learn more about the types of laser technologies at Finally Make Sense of All The Different Types Of Lasik

Treatable causes of vision problems

It is important to note that there can be a variety of causes for halos, glare, starburst, etc. And in fact, there are many treatable causes. This could be residual prescription or astigmatism. This could be dry eye causing worse vision.

Treating those causes can improve those extra vision symptoms.

Learn more about the other causes at The Top Causes of Blurry Vision After Lasik

The Long Term Side Effect

After lasik, you will have a lasik flap on the the cornea. This lasik flap will never heal to be 100%. There will always be a risk that this lasik flap could be disrupted.

This is the long term permanent side effect of lasik.

But is this something to worry about? Probably not.

The chances of that lasik flap posing an issue in the future is extremely low. Especially with modern laser-created lasik flaps.

Modern laser-created lasik flaps have a much more sophisticated shape compared with lasik flaps created with a blade. This allows laser-created lasik flaps to lock in place better. In addition, the edges of the lasik flap develop a small amount of scarring to further secure the lasik flap in place. All of this has allowed laser created lasik flaps to be 10x stronger than lasik flaps in the past created with a blade.

In fact, it’s hard to cause an issue with the lasik flap. Lasik flaps can remain stable even despite significant trauma to the eye.

Check out more at What If I Get Punched In Eye After Lasik?


Lasik will have some side effects. This includes very well known ones such as dry eye and vision symptoms such as halos, glare and starbursts. But this also includes very short term ones as well as the permanent side effect of having a lasik flap. Fortunately modern lasik, has considerably improved these side effects making them more of mere annoyances rather than significant issues.

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