Laser eye surgery is a medical procedure that involves the use of laser to reshape the surface of the eye. This is done to improve or correct myopia (short-sightedness), hypermetropia (long-sightedness) and astigmatism (uneven curvature of the eye’s surface). The first laser sculpting procedures were performed over 30 years ago.
The cornea is the transparent tissue that covers the front of the eye. It helps to control focusing. During laser eye surgery, a computer-controlled excimer laser is used to remove microscopic amounts of tissue from the cornea. The aim is to restore normal eyesight, without the need for glasses or contact lenses.
In one of the operations using the excimer laser, the thin outer layer of the cornea (called the corneal epithelium) is removed and the underlying layers are reshaped. This procedure is known as photorefractive keratectomy (PRK).
In a more commonly used procedure, a thin flap of corneal tissue is created with another laser known as a femtosecond laser. The most widely used one is known as the IntraLase. This flap is then lifted out of the way. The excimer laser reshapes the underlying tissue and the flap is replaced to cover the newly recontoured surface. Alternatively, an instrument with a very fine blade called a microkeratome can be used to make the flap before the excimer laser reshapes the cornea. This procedure is known as laser-assisted in situ keratomileusis (LASIK).
What is myopia?
Myopia, commonly called shortsightedness, is a condition in which light is focussed in front of the retina, resulting in blurred vision. Shortsighted people can often see reasonably clearly at short distances, but will not be able to see distant objects clearly. There is currently no cure for myopia, but spectacles, contact lenses and refractive surgery can all provide good distance vision for people with myopia.
What is Hypermetropia?
When the distance between the cornea at the front of the eye, to the retina at the back of the eye, is shorter than normal, it is called Hypermetropia.
This shortness may make it difficult for the lens of the eye to focus on close-up objects.
Reasons why laser eye surgery may be considered
The reasons why a person may consider laser corneal sculpting include:
- They can’t wear contact lenses and would prefer not to wear glasses for cosmetic reasons.
- They want to engage in work or leisure activities that cannot be done while wearing glasses or contact lenses.
- They don’t want the inconvenience of contact lens wear and the care required.
Medical issues to consider
People thinking about laser eye surgery should consider that:
- You should be at least 20 years old before you consider laser eye surgery.
- The refractive error (prescription in glasses) should be stable.
- People with diabetes, uncontrolled rheumatic conditions, diseases of the immune system or a family history of keratoconus should be very careful in proceeding with laser eye surgery. An experienced refractive surgeon will be able to advise you appropriately.
- Laser eye surgery carries extra risks if performed on people with abnormally shaped or very thin corneas. These are easily assessed during preoperative testing in a refractive surgeon’s office.
What happens during the procedure?
A excimer laser is a ‘cool’ type of laser. It doesn’t burn tissue, but vaporises small amounts of the cornea every time a beam of the laser is pulsed onto the surface of the eye. The diameter of the laser beam and the number of pulses that are directed onto the cornea are carefully controlled using computer technology, so that the surface of the cornea is reshaped.
The procedure is performed using local anaesthetic eye drops and takes between five and 10 minutes per eye. However, the time taken for the reshaping of the cornea with the excimer laser is usually less than a minute.
Long-term outlook for laser eye surgery
Some people who have laser eye surgery will still need to wear glasses or contact lenses to achieve optimum vision, although their natural eyesight should be much improved.
The long-term effects of laser corneal sculpting are believed to be minimal if the eyes are deemed to be well suited to the procedure.