Laser-in-situ-keratomileusis or LASIK is a laser eye surgery technique used to correct long or short-sightedness by reshaping the cornea. It is a simple, out-patient procedure undertaken hundreds of thousands of times across the world, including by high profile sportsmen, such as Tiger Woods and Jonathan Edwards.

But is the procedure safe, what are the risks involved, and what are the chances of success for different groups?

This article on LASIK eye surgery is written by Jackie Griffiths, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.

The procedure

LASIK eye surgery takes around an hour for each eye and is done under local anaesthetic. You will be awake throughout, but you will not be able to see through the eye that’s being treated.

  • A very precise cutting instrument called at microkeratome cuts a small flap in the surface of the cornea to expose the middle.
  • Small and very carefully measured amounts of the cornea are then cut away using a computer-controlled excimer laser. This is a painless process and uses a ‘cool’ light.
  • The flap is then repositioned and stays in place by suction without stitches.
  • Antibiotic drops are added to prevent infection and the eye is patched for 24 hours.

Who can have LASIK? 

LASIK eye surgery can be used to treat short-sightedness, long-sightedness, and astigmatism. However, it cannot treat age-related long-sightedness, as this is due to problems with the lens not the cornea.

You should wait until your prescription has been stable for at least 12-18 months before you have the treatment, or you may need further surgery as your sight changes. For this reason, patients should be at least 21 years old.

You cannot have LASIK surgery if you have diabetes, if you are pregnant or breastfeeding, or if you have a condition that affects your immune system, such as HIV or rheumatoid arthritis.

Success rate

The success rate varies depending on the severity of your eyesight problem. In a recent review by the National Institute of Clinical Excellence (NICE), 63% to 79% of people with mild-moderate short-sightedness had normal vision after LASIK treatment. However, in patients with moderate-strong short-sightedness, this figure dropped to 26% to 36%, demonstrating that this procedure is not as well suited to these patients.

The risks

Many thousands of people have undergone highly successful LASIK eye surgery without any problems or complications at all. However, there are well-established risks, and you should consider these carefully before choosing the treatment.

One review by NICE found problems in 56 out of 1,062 eyes treated, with the sight in 50 eyes actually getting worse after the treatment.

There are four major areas of concern with LASIK surgery:

  • Flap problems – NICE found that around 4% of cases experienced flap problems, including folding, breakage, and in-growth into the cornea itself.
  • Inaccurate surgery – NICE found that in 0.6% of cases the surgeon misjudged the amount of correction needed.
  • Corneal thinning – NICE found that in 0.2% of cases, the cornea became dangerously thin, reducing eyesight and risking total loss.
  • Corneal infection – NICE found that in 0.16% of cases the cornea became infected with microbial keratisis.

Although these risks are small in each case, together they represent a greater than 1 in 50 chance of problems. Furthermore, you should be aware that there are no guarantees of success or ‘normal eyesight’ following treatment, as factors such as the way your eye heals can affect the outcome.

The NICE review of LASIK surgery concluded that: “Glasses and contact lenses are a safe way of correcting eyesight problems, so a surgical treatment such as LASIK would need to be very safe before it could be seen as a routine alternative”.

The procedure and possible complications should be explained to you in detail by your surgeon in order for you to give ‘informed consent’. You need to decide whether the advantages of good eyesight without glasses or contact lenses outweigh the risks posed by LASIK laser eye surgery.

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