June 26, 2023First Posted: October 21, 2021
Last Updated: June 26, 2023
| Lasik

Must Know Lasik Complications in 2023. Is Lasik Safe?

By Barrett Eubanks, M.D.

Must Know Lasik Complications in 2023. Is Lasik Safe?

Is lasik going to cause me to go blind? I can't blame you for asking that question. Lasik is a totally optional procedure. You can do just fine sticking with glasses to correct vision.

Lasik has also developed a certain notoriety to it. If you do enough internet searches, you will see conflicting opinions on whether or not lasik is safe. A large and vocal anti-lasik crowd has emerged.

It’s hard to sort through all the noise and figure out the real risk of lasik.

With current lasik laser technology, it has become very rare for people to have issues with lasik. But it can happen and it is important to know about.

So, today we will talk about complications. A complication can be defined as any unplanned medical problem that occurs during of after the lasik treatment. This is distinct from side effects which are expected but unwanted effects from lasik. I cover side effects in Known Lasik Side Effects You Can Have. So read both if you want to completely understand lasik.

And cozy up on the couch. To truly cover everything, it makes for a pretty hefty article. So read on!

Prescription Off Target

Wanna know the most common complication after lasik? It’s that lasik may not correct your entire prescription. You may have some prescription remaining.

Didn’t think of that as a complication? Well, it’s an unplanned result after lasik. As perfect as it seems, lasik isn't perfect.

With the most advanced lasers available, the probably of getting 20/20 vision without glasses or contact lenses after lasik is about 95% (or higher; some studies have even gotten 100% rates!).

That means that 1 out of every 20 may not have as good of vision without glasses as they had with their glasses.

Risk of having a prescription off target after lasik Risk of having a prescription off target after lasik; graphic adapted from male female by Cuputo from Noun Project, CC BY 3.0

Note: This isn’t any LOSS of vision. This residual prescription can be corrected with a pair of glasses with a very small prescription. It is more the annoyance that things just aren’t quite as sharp as desired.

Don’t want to have to wear glasses after lasik to see? Can’t blame you. But you may not be able to change your risk of this happening.

  • The risk increases the more prescription and / or astigmatism you need treated
  • Also the older you are, the greater the risk of having residual prescription
  • Using older laser generations will reduce the accuracy of lasik. Learn more about the different types at Finally Make Sense of All The Different Types Of Lasik.

But one way to reduce the risk of your prescription being off target is by having your lasik done with an experienced surgeon and clinic. Note: this is a theme we’ll see time and time again throughout this article.

To get the optimal results with lasik, it’s important to feed good data into the laser to get good results from the laser. This means feeding in an accurate prescription. Good clinics go out of the way to make sure the prescription they are measuring is the most accurate one possible.

In addition, good surgeons constantly refine their treatments based upon their results to improve accuracy.

However, if you are one of the unlucky 5%, this is a chance you may not even notice it. The vision may be good enough for you even if it isn’t absolutely perfect. Because of this, the risk of needing to do anything about the residual prescription can be 0.5% or less. Much better odds.

What can be done about residual prescription

In the event there is significant remaining prescription after lasik, it's not the end of the world. Glasses and / or contact lenses are the easy fix. But you already knew that. But there is another way.

More likely than not, this residual prescription can be surgically treated instead through a lasik touch up enhancement procedure. The lasik flap is re-lifted and folded back, the additional prescription is treated and the lasik flap is replaced.

Learn more about this touch up procedure at When A Lasik Touch Up Enhancment Can Be Done.

Flap Issues

Moving on from the prescription being off target, we start to head into issues that can potentially be more serious. First let’s cover issues that can happen with the lasik flap. Broad category, but this will include (in chronological order of when it can happen):

  • Laser Problems
  • Irregular flap creation
  • Debris underneath lasik flap
  • Wrinkled or displaced lasik flap
  • Epithelial Ingrowth

Laser problems

Technology works; Except when it doesn’t work as perfectly as we want. And somewhat similar to how the laser may not be perfect in treating the prescription of your eye, the laser may run into problems creating the lasik flap.

To create a complex lasik flap with a laser, the laser must ensure that the eye doesn’t move. Rather than relying on you to be still at the micron level, the laser instead comes with a suction ring to physically attach the laser onto the surface of the eye. This ensures that the laser knows exactly where it is treating.

Suction Break

This suction works well for most people, but rarely there can be a break in suction during the procedure. This can lead to an incomplete lasik flap. In some cases, the suction can be re-applied and the procedure continued, but other times it’s safer to stop the lasik procedure and continue with PRK at a later date. Read more at This Is The Purpose Of The Lasik Suction Ring.

Air Bubbles Inside Eye

To create the lasik flap, the laser strings together tiny microscopic overlapping air pockets. These air pockets connect to form the 3D shape of the lasik flap. But where does the air go?

Normally, the air vents to the side and out of the way. But rarely, some this air can vent into the eye.

Not a long term problem. The air will just dissolve. But creates a short term problem.

When the lasik laser performs the prescription treatment, it locks onto and tracks the pupil to make sure the treatment stays centered. However, when you have air bubbles inside the eye, and are lying on your back, these air bubbles float to the center of your eye and obstruct your pupil. This prevents the laser from tracking the eye.

So to allow for a safe treatment, lasik must be delayed until those air bubbles dissolve enough. That can be anywhere from half a day to the next day.

Irregular flap creation

Sometimes the laser works, but the flap isn’t perfect.

  • This can happen if the laser has a hard time treating some portion of the lasik flap. This can leave an irregular margin at the edge of the lasik flap or in worst case this can make for a lasik flap which is unable to be folded back.
  • This can also happen if the air bubbles from the flap break through a weak part of the cornea to the surface; leaving a “hole" in the lasik flap (Called a vertical gas breakthrough).

Both of these issues can leave part of the flap irregular and / or increase the risk that the lasik flap could tear.

The risk of this happening is greater if there are significant scars on the cornea. Scars are disorganized and can interfere with the predictability of the laser treatment.

The chances of an irregular lasik flap interfering with your vision is low. The problem area would have to be in the center of your vision. But having an irregular lasik flap could cause the lasik treatment to aborted with PRK performed at a later date to avoid the irregular flap causing extra issues.

Some debris underneath lasik flap

During lasik surgery, some things floating in the tears on the surface of the eye can become trapped underneath the lasik flap when the lasik flap is re-positioned.

This can include

  • Oil secretions from your eyelids
  • An eyelash
  • A surgical fiber

A good surgeon will perform a thorough wash underneath the lasik flap to remove any potential debris and examine for any large objects.

But fortunately, if there is any leftover debris, it doesn’t tend to cause any issue and can just be monitored.

A wrinkle in the lasik flap

Even with a perfectly created lasik flap, there is a chance that this lasik flap may develop a wrinkle. After-all, the lasik flap is pretty thin. And just like a thin bed-sheet, a small wrinkle or fold can develop.

A wrinkle or a fold in the lasik flap isn’t going to spontaneously develop. Either it exists immediately after the lasik flap is re-positioned or something happens later (such as rubbing the eye) to shift or dislocate the lasik flap out of position before the lasik flap fully heals up. This is part of the reason many surgeons like for you to go home and sleep after lasik as the risk of this happening is greatest within the first day. If you rub your eye before lasik heals up, you can cause the flap to shift out of position. See also Everything You Need To Know About Flap Dislocation After Lasik.

But fortunately, with most wrinkles, chances are you won’t even notice it. The vast majority don’t cause any issues with vision.

In addition, significant wrinkles that do affect vision are pretty uncommon.

  • The risk of developing a significant wrinkle with laser-created lasik flaps is about 1 in 500 or less. The risk of the lasik flap dislocating later to cause a much more significant wrinkle is even less than that.
  • Visiting a good an experienced lasik surgeon can also unsurprisingly reduce the chance of having any wrinkles in the lasik flap.

Learn more about significant wrinkles at These Are The Important Lasik Wrinkled Flap Symptoms

What’s done about wrinkles or a dislocated lasik flap? Pretty simply, the lasik flap is smoothed out and re-positioned.

Epithelium growing underneath lasik flap

On the surface of the cornea is a thin layer of cells called epithelium that coat and protect the remaining cornea beneath. The discomfort the first day of lasik comes from the lasik flap creating a scratch through this sensitive epithelium layer. But this layer rapidly grows to heal that scratch.

But this layer can also grow TOO much and start to grow in areas that it isn’t supposed to - such as underneath the lasik flap. This is called epithelial ingrowth.

Having issues with the lasik flap can increase the risk of this happening. Essentially if the lasik flap isn’t sitting smoothly against the eye. The epithelium can take advantage of any small gaps at the edge of the lasik flap and start to grow underneath.

As with many things mentioned above, the risk of this occurring can be as low as zero with good surgery techniques - ie, a good experienced surgeon.

  • But the risk does increase with any extra procedures that manipulate the lasik flap (which is most procedures you may possibly need after lasik such as fixing a lasik flap wrinkle).
  • But the biggest risk comes from lifting up the lasik flap to do a lasik touch up enhancement. Within the first few years, the risk is still low. But as you get further out from lasik, the risk of having the epithelium growing underneath the lasik flap after an enhancement increases considerably.

Similar to lasik flap wrinkles, in many cases the growing epithelium doesn’t affect vision and nothing needs to be done.

But in times where the epithelium grows too much and starts to affect vision, the epithelial ingrowth is fixed by lifting up the lasik flap, removing the epithelium and replacing the lasik flap.

Inflammation Related Issues

Lasik doesn’t really cause a whole lot of inflammation and most people only need to be on steroid eye drops for inflammation for a week afterwards. But there are two things that can occur as a result of excess abnormal inflammation.

  • Transient light sensitivity syndrome
  • Inflammation underneath lasik flap

Transient light sensitivity syndrome

After lasik, it is normal to have some extra sensitivity to light. Much of this is a result of the dry eye that occurs after lasik. Check out more at What Causes Light Sensitivity After Lasik?

But rarely this sensitivity to light can become extreme. To the point of needing to wear sunglasses indoors to help with this extra sensitivity of light. Strangely, this extra light sensitivity may not even start until about a month or two following the lasik procedure.

This unusual cause of light sensitivity after lasik has been termed Transient Light Sensitivity Syndrome.

This sensitivity of light comes from a different reason: extra irritation within the cornea as a result of the lasik laser.

As the lasik lasers have advanced, this has become even less common. And fortunately, this extra sensitivity light responds very very well to a more extended course of steroid eye drops.

Inflammation underneath the lasik flap

Another random event that can occur after lasik is extra inflammation under the lasik flap typically seen the next day after lasik. This condition is called Diffuse Lamellar Keratitis (DLK).

Too much inflammation can cause mild blurry vision and the feeling like there is something in the eye; but it can also cause NO symptoms at all. Your eye may feel totally fine and the extra inflammation is only seen on the eye exam. This is one of the main reasons why eye visits after lasik are important.

Mild cases of extra inflammation aren’t all that uncommon. But these simply need to be watched and treated with extra steroid eye drops. Typically nothing else needs to be done.

Even if the inflammation becomes more severe (which is even more uncommon, about 1 in 1000). The long term outcome after treatment is still typically good.


One significant way one can lose vision after lasik is through weakening of their cornea. This is called corneal ectasia.

Lasik corrects prescription by reshaping the cornea. This process removes corneal tissue (see also How Does Lasik Work?).

If you remove too much cornea tissue with lasik, the cornea can lose it's structural integrity, become weak and change shape. This change in shape can cause your vision to become blurry and distorted.

Change in shape from corneal ectasia after lasik
Change in shape from corneal ectasia after lasik; image by Madhero88, CC BY-SA 3.0, via Wikimedia Commons / modified from original

(This weakening and change in shape is similar to another condition of the eye called keratoconus).

This isn’t something you typically would notice immediately after the lasik treatment. Cornea ectasia can take years to develop; slowly changing your vision in the process.

Over the years, surgeons have learned more about cornea ectasia.

  • Technology has improved our ability to screen for borderline-weak corneas.
  • Lasik treatments have become more conservative to prevent weakening of the cornea.

As a result of these changes, cornea ectasia has become rare with modern lasik. In the past, the risk of ectasia with lasik was about 1 in 1000. But as we move forward in the future with our improved knowledge on what increases the risk of ectasia, this risk may decrease to as low as 1 in 5000.

But even if cornea ectasia does occur, there are treatments which can strengthen the cornea back up again. This treatment is called corneal cross-linking.

If you have routine follow-up and identify and treat cornea ectasia with corneal cross linking before your cornea changes too much, you can prevent any significant vision loss.

Retina Issues

The biggest retina concern after lasik is the development of a retinal detachment. If the retina detaches from the back of the eye, you can permanently lose vision.

Fortunately, lasik does NOT actually increase the risk of a retinal detachment. And in fact the risk may be lower after lasik due to increased screening of the eye to find and treat retinal tears before they lead to retinal detachments.

But the risk of retinal detachment doesn’t go to zero. Being highly nearsighted puts you at an increased risk of a retinal detachment. It just happens to be that highly nearsighted people also frequently get lasik.

But lasik CAN increase the risk of another event happening within the eye. The development of floaters. And while floaters don’t cause you to lose vision, they can be annoying. Read more at This Is The Cause Of Floaters After Lasik


Finally, as with any procedure in the world, there is a risk of infection with lasik. If you have a procedure which breaks through skin (or in the case of the cornea, epithelium), you can have the potential for an infection.

Lasik is no exception.

The good news is that infection after lasik is extremely rare (the risk of infection with contact lenses is actually higher!). Good lasik practices have techniques and cleaning standards to largely make this risk disappear.

  • Autoclaves are used to sterilize lasik instruments.
  • The procedure is performed with sterile surgeon gloves.
  • Betadine antiseptic is frequently used to kill off any bacteria around the eye.

This has dropped the infection rate after lasik to extremely low levels. An infection after lasik is estimated to occur at a rate of about 1 in 25,000.

If you are unlucky and develop an infection, fortunately it can be treated. Just how antibiotics are used to treat an infection anywhere else in the body, they are also very effective with infections on the cornea. By catching the infection early and rapidly treating it with antibiotics, you can prevent the infection from causing any lasting damage to your eyes and vision loss.


Lasik has become one of the safest procedures around. But lasik is still a procedure and with any procedure comes the risk of a complication. And because of complications it is possible to end up with blurry vision after lasik. But fortunately this is rare with good quality lasik from an experienced lasik surgeon.

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