Introduction
Regarding vision correction, there are two types of refractive surgery: LASIK (a Laser that shapes the cornea) or introduction of Phakic Intraocular Lens (a small lens that is introduced inside the eye), both of them are intended to reduce the dependency on spectacles or contact lenses.
For clear vision, the eye's cornea and lens must bend (refract) light rays properly, so that images are focused onto the retina. If the light rays are not clearly focused onto the retina, the images that are seen will be blurred. This blurriness is referred to as a "refractive error."
It is caused by an imperfectly shaped eyeball, cornea or lens. Vision correction through Laser, commonly known as LASIK (Laser-Assisted In Situ Keratomileusis) is a surgical procedure which can reduce a person's dependency on spectacles or contact lenses.
The procedure permanently changes the shape of the cornea (the delicate clear covering on the front of the eye).
LASIK treatment uses an Excimer Laser (an ultraviolet Laser) to precisely remove corneal tissue to correct the shape for better focusing.
LASIK treatment is performed most often on people who have nearsightedness (myopia).
Description
A complete eye examination will be done before surgery to make sure that the patient’s eyes are healthy, making sure there are no irregularities that would prevent LASIK as an option.
LASIK is an out-patient surgical procedure and it will take about 10 to 15 minutes for each eye. For a few seconds, the patient may have the feeling of vision loss, but that is always rapidly recovered from.
LASIK may be done on one or both eyes during the same session.
During LASIK treatment, a special knife (a microkeratome) is used to cut a hinged flap of corneal tissue from the outer layer of the eyeball. The flap is lifted out of the way and a special Laser is used to reshape the underlying corneal tissue.
No stitches are needed. An eye shield or patch will be placed over the eye to protect the flap and to help prevent rubbing or pressure on the eye until it has had enough time to heal.
Anesthesia
The only anaesthetic used is an eye drop that will numb the surface of the eye. The procedure is done with the person awake.
Indications
LASIK treatment is done most often on people who use spectacles or contact lenses because of myopia (nearsightedness). It is occasionally used to correct hyperopia (farsightedness).
It may also correct astigmatism. Patients should be at least 18 years old. If the patient is myopic, LASIK Treatment should postponed for at least one year until the refraction has stabilised, because myopia may continue to increase in some patients until their mid to late 20s.
LASIK treatment may not be recommended for patients with diabetes, rheumatoid arthritis, lupus, glaucoma, herpes infections of the eye, or cataracts.
Pregnant or patients nursing infants are not eligible because these conditions might change the measured refraction of the eye. Certain prescription drugs, such as Prednisone should be avoided before undergoing LASIK.
Risks, Complications and Side Effects
Over- or Under-treatment of the condition may occur requiring : additional surgery, contact lens, or spectacles. Reading spectacles may still be needed after surgery when patients reach their 40s. Some patients, although they may see much better than before LASIK without spectacles, will still need spectacles for their best vision.
Patients can also experience: eye dryness, scratchiness, presence of patches of red or pink in the white of the eye, light sensitivity, some dificulties with night driving, or visual symptoms, such as: glare, haloes, a decrease in contrast sensitivity and even with 20/20 vision, objects may appear fuzzy or grey.
Corneal infection, corneal scarring, permanent warping of the cornea and an inability to wear contact lenses is infrequent. Vision impairment may arise: such as a loss of vision, not seeing as well after surgery as before the surgery, even with spectacles or contact lenses. Permanent vision loss is rare.
Post-operative care
Immediately following the surgery, there may be a sense of burning, itching, or a feeling that something is in the eye. There may be mild discomfort for which the doctor may prescribe a mild pain relief medication.
It is very important NOT to rub the eye after LASIK, to ensure that the flap does not dislodge or move. On the day of surgery, vision is generally blurred or hazy, but by the next day, the blurriness improves.
The doctor should be called immediately if there is severe pain or if any of the symptoms worsen before the scheduled follow-up appointment (24 to 48 hours after surgery).
During the first doctor visit after the surgery, the eye shield will be removed and the doctor will examine the eye and test the patient’s vision. The patient may receive eye drops to help prevent infection.
Patients should not drive until the vision has improved enough to safely do so. Other things for patients to avoid include: swimming, hot tubs, whirlpools, contact sports, lotions, creams and eye make-up for between 2 to 4 weeks after surgery. The doctor will give the patient specific instructions.
Convalescence
The most common complaints after LASIK treatment are glare, haloes and difficulty with night driving. Often, these problems will go away after 6 months, but a small percentage of people will continue to complain about glare. Sometimes, additional surgery may be needed in order to get the best possible vision.
These further operations may be called "enhancement surgery." Generally, while the distance vision may improve with enhancement surgery, other visual symptoms such as glare or haloes may not.
The American Academy of Ophthalmology (AAO) reports that out of approximately 500,000 Americans who had LASIK surgery in 1999, 70% had 20/20 vision after surgery. If the distance vision has been corrected with LASIK, it is likely that patients may still need reading spectacles when aged about 45.
Recovery Time
Patients can already see the difference within 24 hours of LASIK surgery, but optimum vision may not fully develop for up to 3 to 6 months.