The Excimer Laser
The modern method of using the Excimer Laser to correct refractive errors is a breakthrough that has benefited millions of patients who were shortsighted or had other refractive errors. The technique has advanced to a point where we can reliably predict that Excimer Laser treatment will, in suitable patients, provide good vision without glasses or contact lenses. For people who undergo Excimer Laser procedures, being independent or having minimal dependency upon corrective lenses is a major benefit.
Excimer Laser treatment is an elective procedure and, as with any form of surgery, deserves careful consideration prior to proceeding. Please contact us and we will answer any questions that you may have. We offer a free screening test and we also have an educational video for you to watch. If you are a good candidate for the Excimer Laser procedure, then the decision to go ahead is entirely yours to make.
The Excimer Laser was originally developed for the manufacture of computer microchips, where it was used to etch the circuits. However, its extreme accuracy resulted in it being developed as an eye laser. It is now used to re-sculpture the corneal surface of patients with refractive errors. It is a cold laser and does not burn but rather evaporates tissue by breaking down molecular and atomic bonds.
The Excimer Eye Laser is extremely accurate and removes only 0.25 microns (1/4000 th millimetre) of tissue per pulse. In most cases the Laser treatment takes only 10 to 40 seconds depending on how severe your refractive error is. The Excimer Laser accurately re-sculptures the cornea to make the curve of the cornea balance the length of the eye, light rays are then focused normally on the retina.
In myopia the cornea is flattened (as shown above), whereas in hyperopia the cornea is made more curved. With astigmatism the surface of the cornea is re-sculptured to a regular curvature. This advanced surgical technique using the Excimer Laser can accurately re-sculpture your cornea thus permanently correcting your myopia or other refractive error – allowing you to be independent or less reliant on glasses and contact lenses.
In the original method of treatment the Laser was used on the surface of the cornea. This method is known as photorefractive keratectomy (PRK). Although still sometimes used for low degrees of myopia and hyperopia, PRK has been largely superseded by the Lasik method in which the Laser treatment is applied under a protective corneal flap (this is not to be confused with Lasek which is a variation of PRK!).
Lasik is a modern adaptation, using the Excimer Laser, of a technique that has been in existence for almost 30 years. A thin protective corneal flap is raised, rather like a trapdoor. The front surface of the exposed cornea is resculptured by the Excimer Laser. At the end of the procedure the protective flap is simply replaced. The Lasik technique leaves the original surface of the cornea virtually intact and the mild healing process results in minimal regression and no scarring. The Lasik procedure is now regarded as the most advanced refractive surgery technique.
Who is suitable?
How can you find out if you are a good candidate for Excimer Laser? Most patients with myopia, astigmatism, and hyperopia are suitable for Excimer Laser treatment. Patients with presbyopia alone cannot normally be treated by the Excimer Laser but may have one eye made a little myopic for reading. This is called monovision and to determine whether it is suitable for you requires a consultation to discuss the pros and cons. Another alternative is the use of implants (see next section).
During the free screening test that we offer, we can give you a good idea as to whether you are a possible candidate. However, before proceeding with treatment, you will need a full eye examination by Dr. John Hill to exclude any diseases and contraindications.
The following tests will be performed and the following information will be requested.
- How much myopia, or other refractive error, is present? A refraction test will measure the amount of refractive error present.
- A measurement of your cornea is made by computerized corneal topography, that produces a contour map to show the curve of your cornea. This information is also fed into the laser to give a more accurate customized treatment.
- What is the thickness of your cornea? An ultrasound probe is used to measure the thickness of your cornea in microns.
- We will measure the size of your pupils in the dark.
- Your eyes will be examined to determine that no other medical eye problems are present which may interfere with the Laser procedure.
- A pressure test is also routinely performed to exclude glaucoma.
- Is your refractive error stable?
- Personal information about allergies and other medical conditions that may effect the laser treatment will be requested.
- Does your profession or occupation have a visual requirement?
- Do glasses or contact lenses satisfy your visual needs?
- What do you expect from the Excimer Laser procedure?
Please note: Realistic expectations and the ability to follow instructions are essential for a successful result.
A computerized corneal topography unit being used to measure corneal curvature
The corneal scan then produces the computerized image shown below.
A corneal map showing the curvature of the cornea