What is it?
LASIK (laser assisted in-situ keratomileusis) surgery is an operation that is done to correct nearsightedness (myopia) by using laser light.
The cornea is the clear/transparent film in the front of the eye that lies just in front of the coloured part which is the iris.
The cornea allows light to enter the eye and also refracts/bends the light and focuses it at the back of the eye which is the photosensitive area called the retina. If there is a problem with the shape of the cornea, the light focuses in front of and not exactly on the retina and this doesn’t allow you to clearly see objects that are away from you. In LASIK surgery, the cornea is properly reshaped by the laser to allow the light to focus on the retina. LASIK surgery can be used for people with mild, moderate or severe myopia. It's not indicated for people who:
- are aged less than 18 years.
- have not had stable vision for at least one year.
- have any other diseases of the cornea.
Although nearsightedness is the main indication for LASIK surgery, it has also been used to a much lesser degree for the correction of hypermetropia and astigmatism. In hypermetropia (farsightedness) the cornea focuses the light behind the retina, while in astigmatism the light has a split focus which results in blurred vision.
The operation takes about 30 minutes and is carried out as a day surgery case, which means that you will go home on the same day of the operation.
The operation takes place in a room that has the Laser system. You will be on a special chair that is similar to a dentist's chair. You will be lying on your back and your eye will be numbed with some anaesthetic eye drops. A special device is used to keep the eyelids open. A microscopic knife will be used to cut a small flap in the centre of the cornea. The cut is not complete; a small bridge of tissue is left to keep it in contact with the rest of the cornea. The flap is then lifted and folded back. Via this opening the laser light can get through to the inner aspect of the cornea. The laser system will then be positioned close to your eye and the laser light will be directed towards the inner aspect of your cornea. The laser light vaporises the tissue of the inner aspect of the cornea and reshapes the cornea in such a way that after the operation it will focus the light on the retina allowing you to clearly see objects that are away from you. The amount of laser light/energy that will enter your eye and the way it will reshape the cornea is controlled by a computer which is very accurate. After the laser treatment the flap of the cornea is put back in place but it is not stitched. A pad/shield will be placed over the eye at the end of the procedure to protect it.
This is an entirely elective procedure that is being done to help you to get rid of the inconvenience of wearing spectacles/glasses or contact lenses. You don’t have to have LASIK surgery and therefore, you need to have a very detailed discussion with your ophthalmologist before you decide to have the procedure.
Before the operation
Stop smoking and get your weight down if you are overweight. (See Healthy Living). If you know that you have problems with your blood pressure, your heart or your lungs, ask your family doctor to check that these are under control. Check the hospital's advice about taking the Pill or hormone replacement therapy (HRT). Bring all your tablets and medicines with you to the hospital. On the ward, you may be checked for past illnesses and may have special tests to make sure that you are well prepared and that you can have the operation as safely as possible. Many hospitals now run special preadmission clinics, where you visit for an hour or two, a few weeks or so before the operation for these checks.
If you are using contact lenses, you need to stop wearing them three to four weeks before the operation and use glasses instead. This is because contact lenses affect the shape of the cornea and it needs three to four weeks to revert to its natural shape. If the cornea does not have its natural shape before the operation, the laser cannot reshape it accurately and effectively to provide a successful result.
After - in hospital
Most patients experience little pain or discomfort after LASIK surgery but may have some minor swelling of the eye. You may be given tablets to control the pain or discomfort. Your eye may also itch or produce tears. Don’t rub it! You can wash, bathe, or shower normally after the operation, but you must not get water in your eye for a month. If you have your hair washed, have it done with your head leaning backwards. Do not use makeup on your eyelids for one month. You will be given a supply of eye drops and be shown how to put them in your eye. The drops are used to prevent infection.
You will be given an appointment for the outpatient department for your first check-up one to two days after your operation. From then on you will have regular appointments (the frequency depends on your progress) for six months after your operation. The nurses will advise about sick notes, certificates, etc. You are advised to have somebody with you to drive you home.
After- at homeEven if everything is well during your first visit as an outpatient one to two days after your operation, you will continue to have your eye covered by a pad and a protective plastic shield. This is to stop you touching your eye, especially when you are asleep. You MUST wear the eye shield to protect the operated eye at night, or if you sleep during the day. You will be told in the outpatient clinic when you can stop using the shield (normally about one month). During the day you can use any glasses you were using before the operation. Sun glasses are a good idea to protect your eyes from the glare. You must not use contact lenses.
After the operation any activity that can jolt the eye must be avoided. Contact sports must be avoided after LASIK surgery for at least four to six weeks. Plan to go back to light work in about two to three weeks, and a more heavy/manual job after about three to four months.
Initially, your vision might be blurry for the first few days after the operation but it will gradually improve. It usually takes three to six months to experience the maximum improvement and stability of your vision. You must be very careful with driving because your sight may not be as good as you think it is. Ask the doctor whether your sight is good enough to drive. If in doubt, don't drive.
Complications occur in 1 to 5% of cases. The eye may become infected in the area of the operation. Drops of antibiotics and of anti-swelling medication may be needed to treat the infection. You may also experience the problem of dry eye which can cause irritation, redness and discomfort. This is treated by using eye drops that help to keep the area wet until the symptoms go away.
The dislocation of the flap after the operation can be a problem which has to be treated promptly with another operation to put it back in place before it affects vision. Sometimes, while the cut around the flap is healing, a lot of scarred tissue can develop and this can blur your vision. You may need further laser treatment or another operation to deal with this problem, but this is not always successful.
LASIK surgery can sometimes under-correct or over-correct the problem of myopia or, rarely, can make it worse. In this situation you may require further laser treatment but there is a chance that the result will not be successful.
LASIK surgery significantly improves the vision of 80 to 90% of people with less than 6 diopters (a unit used to measure how well a person sees - the more the diopters the worse the vision) of myopia. The procedure results in significantly better vision in 30 to 60% of people with 6 to 12 diopters of myopia.