Laser eye surgery has been available for more than 20 years and more than 2 million people across the globe have undergone the procedure, enjoying crystal clear vision without the need for glasses and contact lenses. However, as with all surgical procedures, there are risks, although the complication rates are usually very low.

Surgical technology has evolved massively and laser eye surgery is considered one of the safest in the world. Around 1 in 1000 laser eye surgery procedures result in some sort of complication. The vast majority of complications that do arise can normally be rectified by an experienced surgeon.

It’s important to understand the risks before undergoing any surgery.

Laser Eye Surgery Risks:

• Discomfort following surgery: This varies from person to person. LASEK is considered slightly more uncomfortable and has a longer healing time of around a week, compared to a day or two with LASIK treatment.
• Allergy to the anaesthetic eye drops: This is extremely rare and will lead to inflammation and possible scarring of the cornea. Less than 1 in 10,000 people will be affected by this complication which is treated with anti-inflammatory eye drops should it occur.
• Dry eyes: This is one of the most common complaints following surgery and for this reason, your tear film will be assessed thoroughly during your initial consultation. Dry eye typically resolves itself over the first 6 months following the procedure as the eyes naturally heal. For more detailed information on this complication, you can read the following guide: dry eyes and laser eye surgery
• Eyelid droop: (Ptosis): This is rare and usually resolves itself within 2 weeks of the procedure. If necessary it can be rectified with surgery but this is not normally required.
• Corneal Infection: This is an uncommon risk of laser eye surgery and can normally be treated with antibiotics and steroid eye drops as required. If this does occur your eyes will take longer to heal following surgery and you are likely to be in more discomfort.
• Irregular astigmatism: This type of astigmatism can lead to you experiencing ghosting around images which are especially noticeable at night (low light levels). This can normally be treated by further laser treatment to eliminate this unwanted prescription.
• Regression: This means that your vision slowly regresses over time following surgery. You may have perfect vision immediately following your surgery but over time your prescription deteriorates. It is very unlikely that it will regress back to your original prescription but it still may be enough for you to need spectacles again. A typical example of regression would be if your original prescription was -5.00 and then you regressed back to -1.00 over the first 12 months following surgery. The higher your original prescription was, the more likely you are to regress. Plus prescriptions (e.g. +5.00) are also more likely to regress than minus prescriptions (short-sightedness). Normally if regression does occur your surgeon can easily carry out a laser enhancement (e.g. a second laser treatment) when your eyes have fully healed. Most clinics do not charge for this re-treatment although you will need to check this with them prior to going ahead with your surgery.
• Corneal haze: The cornea is the part of your eye which is lasered during surgery and it can become cloudy if it does not heal properly after the procedure. Corneal haze can result in reduced vision but it generally improves over time. Your surgeon will prescribe you with medicated eye drops to help reduce the haze if it is seen as a problem.
• Presbyopia: (needing reading glasses as you get older): This is not actually a risk of laser eye surgery but it is still something that to consider. Everyone needs reading glasses as they reach the age of about 45 years old and this is exactly the same if you have had laser eye surgery. This natural loss of reading vision with age is called presbyopia and if you are over 45 years old and considering having laser eye surgery you may want to consider treatment options that correct both your distance and reading vision. You can read more about these options by clicking the following guide: Laser eye for reading
• Night vision problems: Examples of night vision problems are haloes, glare and starbursts around lights which are typically noticed in low light levels. Although this is a common risk, with the advancement in laser technology it is now becoming less of an issue. For those people at a higher risk of suffering night vision problems such as those with large pupils, your surgeon may recommend Wavefront laser eye surgery. Read more about laser eye surgery and night vision problems in our detailed guide.
• Over/under correction: Although laser eye surgery is becoming increasingly accurate, overcorrecting or under correcting your prescription is still one of the most common risks of laser eye surgery. Although this is frustrating it can be easily rectified by a laser re-enhancement once your eyes have fully healed following your initial surgery.

In addition to the risks above, LASIK has its own specific complications due to the creation of the flap during the procedure. Put simply, the flap is a thin layer of the cornea that is separated from the surface of the eye prior to the laser is applied. No flap is created during LASEK and hence the following risks are not associated with the LASEK procedure.

LASIK Specific Complications:

• Wrinkled/uneven Flap: This can result in a distorted cornea which can cause blurred vision. This complication can generally be easily treated by re-lifting the flap and smoothing it over.
• Epithelial ingrowth/trapped debris: The epithelium (outer layer of the cornea) sometimes grows below the flap that is created during LASIK. Another LASIK risk is debris becoming trapped beneath the flap which like epithelial in growth, can cause your vision to be blurred after surgery. Both these cases can be treated easily by your surgeon by re-lifting the flap and thoroughly cleaning it before resealing it again.
• DLK: Diffuse Lamellar Keratitis can be a severe LASIK risk and occurs when dead cells which lie beneath the flap cause an inflammatory response. This can lead to scarring of the cornea which can result in reduced vision. Depending on how serious the inflammation is antibiotics and topical steroids may be used to treat it. In most cases, this condition can be successfully treated meaning no loss of vision occurs.
• Keratectasia: Although rare, this is of the most serious complications of LASIK. If during surgery the laser removes too much tissue (cornea) or the flap that is made is cut too deep, the structure/strength of the cornea can become compromised. This can result in the cornea bulging forward in an irregular manner resulting in astigmatism which causes blurred vision. This can often be treated with contact lenses, spectacles or possibly a laser enhancement.

Whilst there are risks associated with the creation of the flap these are becoming less and less common especially with the development of bladeless LASIK, which effectively uses a laser to create the flap (femtosecond laser) as opposed to a mechanical blade during standard LASIK. This is often referred to as Intralase LASIK and can be read about here.