(Excimer Laser Surgery)
Did you know…
- Approximately half the population suffers from nearsightedness (myopia), farsightedness (hyperopia) or astigmatism and need eyeglasses or contact lenses to see properly?
- There are several modern surgical techniques available to reduce or eliminate the need for corrective lenses for these conditions?
The problem with spectacle wearers
Whenever the light focusing system in front of the eye (mainly the cornea, also the lens) produces an image either in front of (myopic or nearsighted) or behind (hyperopic or farsighted) the retina, vision is blurred and some additional focusing system such as spectacles or contact lenses are necessary to shift the focus onto the retina.
The further the image is from the retina, the thicker the spectacles (or contact lenses) have to be to achieve this focus on the retina and therefore clear vision.
We cannot shorten or lengthen the eyeball, but we can now alter the shape of the front of the cornea sufficiently in most cases to shift the focus (image) from its abnormal position to the retina, and therefore restore good vision without glasses.
There is obviously some risk associated with this, so however small this risk might be, surgical approach is not considered if patients are comfortable with their glasses or their contact lenses.
The altered shape of the front of the cornea can be achieved via Laser (Excimer) Refractive Surgery as follows:
Laser In-Situ Keratomileusis
Laser in-situ keratomileusis, or LASIK, is considered safe and effective for patients with low to high myopia, with or without astigmatism, and low to moderate hyperopia.
The ophthalmologist uses a microkeratome (mechanised corneal cutter) to cut a thin, hinged layer in the cornea, called a flap. The flap is then laid back and the surgeon uses an excimer laser beam to flatten the underlying cornea by vaporising a thin layer of tissue. The flap is gently put back in place. The cornea heals without any stitches.
Local anaesthetic drops are used (no injections) to render the eye insensitive.
Mild sedation is also usually advisable. Because of this, arrange for someone to drive you home after surgery.
You will wear eye shields until the next morning.
Who can have this?
Not all people with refractive errors are good candidates for refractive surgery. Your ophthalmologist is the best source of information on refractive procedures and the options you have to correct your particular refractive error.
Patients with thicker spectacles benefit most from this procedure. There is no doubt that they are heavily spectacle dependant, and in the event of the loss of the glasses or the glasses being out of reach, the patient can find themselves in a debilitating situation.
Lasik aims to eliminate (or substantially reduce) this handicap. You may need thin glasses afterwards for very sharp vision, but should have about an 80% chance of going without spectacles 80% of the time – depending on how bad you were before.
What age does one have to be?
Minimum of 18 years, with refraction having remained stable for at least one year.
There is no maximum age but patients over 45 years old should remember that they will not be able to read without glasses after this procedure.
As with any surgical procedure, there are risks associated with refractive surgeries. Patients need to consider carefully whether they are willing to accept those risks before undergoing surgery. Refractive surgery is an elective procedure and is rarely covered by health care insurance.
- An imperfect flap at operation. If this happens, no laser is applied, the flap is replaced – and reoperation performed 3 months later.
- Epithelial defects at operation – these heal within 48 hours and will be covered with a bandage contact lens.
- Infection – extremely rare, statistics show this to be about 1:50 000 operations.
- Corneal “haze” or light scarring – about 3%. This would cause mistiness of vision, halo’s around lights (especially at night), and may need lifting of the “flap” to remove unwanted material.
- Regression – some patients tend to revert partially to their previous refraction. A “top up” may be possible.
- Haloes around lights, especially when driving at night – this gets better after 6 months but never completely disappears.
- Inflammatory reaction in cutting plane – this is transitory and will be treated with drops or by lifting the flap to scrape out inflammatory cells.
- Transient dryness for about 2 months post operatively.
With all types of surgery there is a possibility of other complications including those due to anaesthetic agents, drug reactions and factors which may involve other parts of the body. Since it is impossible to state every complication which may occur as a result of any surgery, this list is incomplete.