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LASEK and LASIK – what’s the difference?

Written by: Mr Alexander Ionides
Published: | Updated: 07/02/2019
Edited by: Emily Lawrenson

Laser eye surgery is one of the most popular and commonly performed eye surgeries in the world, with millions of people around the globe choosing to undergo the procedure in order to permanently correct their vision. Here, top ophthalmologist and expert in laser eye surgery, Mr Alexander Ionides, explains what the difference is between the types of laser surgery, and what they offer patients.


LASEK might look as if you’ve made a typo when writing the more well-known LASIK surgery, but it is a procedure in its own right: while LASIK remains the most popular laser surgery, not everyone is suitable for the procedure – meaning LASEK may be a better option for certain people.

What is laser eye surgery?

Laser eye surgery is used to correct refractive errors, a group of conditions which affect the way that light hits the retina, in turn affecting vision. Refractive error is commonly corrected with eye glasses or contact lenses, and laser eye surgery offers a permanent solution to this.

Laser eye surgery uses a special laser to reshape the cornea, so light enters the eye and hits the retina in a different way to how it did before. In most cases, the surgery is successful and can correct astigmatism, long-sightedness, and short-sightedness.

How is LASIK performed?

LASIK is the most common form of laser eye surgery, and it is performed using a precision laser which makes a thin flap in the cornea. The surgeon can then remove (ablate) thin layers from the cornea and reshape it in order to correct the refractive error. The flap is then returned to its natural position, and will heal naturally without needing stitches.

Who is suitable for LASIK?

Refractive errors generally do not stabilise until we hit our late teens, or early twenties. Therefore LASIK should only be performed on adults (over 18, but in most cases those 21 and over are considered candidates), and the ophthalmologist will look at your prescription history to check there has not been significant change in the years leading up to your decision to undergo LASIK.

Things which may disqualify you from being a suitable LASIK candidate include:

  • Thin corneas
  • Corneal scarring, for example from a previous eye surgery
  • Being pregnant, or looking to try for a baby in the near future
  • Having large pupils
  • Autoimmune diseases
  • Having diabetes
  • Being on certain medications
  • Diabetic retinopathy
  • Other eye conditions including cataracts, glaucoma, keratoconus, and retinal detachment

The ophthalmologist will assess you carefully to make sure you are a good candidate for LASIK, as they will want to minimise risk of complications from surgery, and offer you a treatment path which yields positive results. It is important to listen to your surgeon’s recommendation and look at other procedures if you are not considered to be a good candidate for LASIK.

How is LASEK performed?

Many who are not suitable for LASIK can be offered LASEK surgery instead. LASEK is very similar to LASIK, but it can be a good option for those who have thin corneas, or ‘flatter’ corneas. In LASEK, the corneal epithelium (the thin outer layer of the cornea) is separated from the layer underneath using a weak alcohol solution, smoothing back the tissue, and creating an incredibly fine flap of epithelium.

The underlying cornea is then shaped using laser ablation, and the thin flap is repositioned on the surface of the eye. A special ‘bandage’ contact lens is then placed on the eye to help it heal and keep the epithelium in place.

Who is suitable for LASEK?

Most patients who are suitable for LASIK are also suitable for LASEK. LASEK is more frequently used with those who have a thinner cornea, or those who are particularly short-sighted. LASEK may also be recommended in those who have a profession or hobby which puts them at greater risk of eye injury (e.g sports players, or those in the military).

Before undergoing laser eye surgery

There are pros and cons for both types of laser eye surgery, but your ophthalmologist will talk you through the risks and benefits before the procedure, to make sure you are completely comfortable with it, and to be sure you have the right expectations. Both LASIK and LASEK are considered safe procedures, but talk to your surgeon and make sure you have chosen the right person for you.

Both procedures are relatively short, lasting from 15 minutes to half an hour, depending on the individual and their prescription. After surgery, vision will return slowly and it is important to arrange for someone to help you home on the day. In the days following, vision will continue to improve.

However, one big difference between LASIK and LASEK is the time it takes for vision to completely improve and for the eyes to heal. LASEK patients take longer to heal, due to the epithelium needing to heal properly. For LASEK patients, 1-2 weeks is standard recovery time, with patients often complaining of irritation in the eyes for a couple of days following the procedure. While the recovery takes longer than traditional LASIK, it is certainly a less risky procedure for those who have thin corneas or are very short-sighted, and opens up the option of surgery for those patients who could not consider it before.

If you are interested in finding out more about LASIK or LASEK, make an appointment with a specialist to discuss your options.

By Mr Alexander Ionides

Mr Alexander Ionides is a leading consultant ophthalmologist with expertise in laser eye surgery, small incision cataract surgery, clear lens extraction, and phakic lens implantation. Mr Ionides qualified in 1989 after his training at University College London medical school, and went on to train in ophthalmology at Great Ormond Street Hospital before joining the world-renowned Moorfields Eye Hospital in 1992. 

Mr Ionides has a strong interest in research, obtaining an MD in cataract genetics and lens research at the Institute of Ophthalmology. He has published numerous papers and has contributed to research and development in both cataract and lens surgery. With a background in both research and many years of practice, Mr Ionides is considered to be one of the best laser eye surgeons in the UK, providing an exceptional level of care and expertise. 

Mr Ionides holds the position of honorary senior lecturer and honorary consultant at St George's Hospital, and is frequently invited to speak at meetings on both a national and international level. 

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