Laser Eye Surgery (LASIK)
Description
The laser is computer guided to reshape the surface of the cornea so that a clear image is obtained at the back of the eye (retina), where the light sensitive cells are located.
The surface of the eye, in front of the coloured iris is called the cornea. It is clear and transparent and allows light to pass though itself, then through the pupil, on through the lens and through the back chamber of the eyeball before it is finally projected onto the light sensitive film at the back of the eye called the retina.
The cornea is therefore the first part of the eye that light passes through. Although it is clear, it does posses some refractive properties, i.e. it can bend light and in so doing, assists the eye in focusing. In fact, the majority of the focusing is done by the cornea.
If the cornea is not shaped correctly, light will bend differently and focus on the area in front of the retina. This produces a blurred or out of focus image. This is usually corrected by wearing spectacles or contact lenses.
LASIK allows precision reshaping of the cornea so that the cornea can correctly focus light onto the retina. It can be used to treat most degrees of myopia but is most effective if the refractive error is less than 6 diopters.
Although this is its main uses, LASIK can these days also be used to correct long-sightedness (hypermetropia) and astigmatism (split focus).
This procedure is usually done under local anaesthetic where the patient sits on a special chair. The eye is numbed using drops and an instrument used to keep the eyelids open so that the whole of the cornea is in full view. A knife is used to cut a flap of cornea from the centre using a microscope so that the inner part of the cornea is exposed. The computer guided laser then vapourises the surface of this exposed area of the cornea such that light is focused precisely onto the retina. After this process, the flap of cornea is put back into position and a pad put over the eye for protection.
Medical Facts
LASIK is not indicated if you are;
- under 18 years of age,
- have not had stable vision for at least one year,
- have any other problems/diseases of the cornea.
You will need to stop wearing contact lenses 3-4 weeks before the procedure to ensure that the cornea is naturally shaped. Otherwise, the computer will mis-calculate the shape of the final result, leading to further blurred vision.
Complications can occur with LASIK in 1-5% of cases. These problems include;
- infection which is treated with antibiotic eye drops,
- dry eye, causing, irritation, reddness and pain. This is treated with eye drops,
- dislocation of the corneal flap.
This requires further surgery to correct,
- scar tissue formation around the healing flap. This may also require further laser or other surgery to correct,
- under or over correction can occur. In this instance, further treatment may be required, but sometimes, a satisfactory result is not acheived.
The procedure requires one day hospitalisation.
Side effects of LASIK are usually mild with some discomfort, watering and itching of the eye. Pain killers can be used to treat pain or discomfort and eye drops will be given to prevent infection. No water must enter the eye and make-up on or around the eye should not be worn for 1 month following LASIK. The surgeon will arrange regular out-patient appointments to monitor progress. Vision will be blurred for several days after the procedure and it can take up to 6 months for visual acuity to become normal.
An eye pad and shield should be worn while sleeping for at least 1 month, especially to prevent touching the eye.
Sun glasses can be worn through the day to protect the eye from glare and contact sports should be avoided for at least 4-6 weeks.
Light work can commence after 2-3 weeks with heavier or manual tasks 3-4 months after LASIK.
How Long Will you stay in Hospital after your Laser Eye Surgery (LASIK)?