What types of laser eye surgery are available?
There are two well established types of laser vision correction that are performed to correct a refractive error. These are laser-assisted in-situ keratomileusis (LASIK) and photo refractive keratectomy (PRK) or advanced surface laser ablation (ASLA). Many different names have been used to market these techniques. For simplicity, this website will refer to LASIK when discussing the procedure that creates a flap in the cornea and changes the shape of the underlying stroma, and PRK or ASLA when discussing the procedure where no flap is created and a laser is used to change the shape of the corneal surface.
PRK/ASLA involves reshaping the surface of the cornea. A specialised excimer laser, removes corneal tissue by vaporising it. This results in a new corneal shape that allows clear focus without glasses or contacts. Because PRK/ASLA reshapes the top layers of the cornea, there can be significant discomfort during the initial days of healing and it often takes a several days to a week to achieve functional vision for normal day-to-day activities.
LASIK, in contrast, gives very rapid visual results and typically only mild discomfort during healing. LASIK involves the use of two different lasers. A specialised cutting laser, called a femtosecond laser, is used to create a superficial flap of corneal tissue. The flap is folded and lifted out of the way, so the excimer laser can reshape the underlying layers. This avoids treating the superficial layers of the cornea, which reduces pain and increases healing time. Both PRK/ASLA and LASIK give excellent and equal visual outcomes when measured at six months after the procedure.
Which laser vision correction procedure is right for me?
If you are considering a vision correction procedure, the first step is to book a consultation with Dr MacIntyre to find out whether or not you are suitable for laser eye surgery. If you are between the ages of 18 and 45 and have had a stable prescription for two years, you will most likely be suitable. During your initial assessment, you will undergo a comprehensive range of eye examinations. This will include assessing your current prescription, the general health of your eye, and your cornea tomography (shape, curvature, and thickness of your cornea). Dr MacIntyre will discuss the results of your examination and make a recommendation for the best procedure for your eyes.
If your cornea is slightly thin, LASIK may be a higher risk procedure because of the need to create a flap. In this situation, Dr MacIntyre may recommend PRK. LASIK also impacts temporarily on the corneal nerve supply and often results in a period of dry eyes. Where this occurs, it usually disappears within a month or two but it is one reason why LASIK is not the best option for patients with chronic dry eye conditions. If you have a particularly high prescription, laser vision correction may not be recommended at all. In this situation, other options may be better, including phakic intraocular lenses or refractive lens exchange. Occasionally, based on your eye assessment details, there may be no good option to achieve an excellent visual outcome at low or minimal risk. Dr MacIntyre believes only in performing refractive surgical procedures if there is minimal risk and will discuss your individual risks at the time of your consultation.
How does laser vision correction work?
A person with 6/6 or 20/20 vision is lucky enough to have a cornea that is perfectly shaped to focus the image clearly onto the retina in the back of the eye.
People who suffer from short-sightedness (myopia), far-sightedness (hyperopia) and astigmatism may have a cornea that is not perfectly shaped. It can be too steep, too flat or too oval to focus light clearly onto the retina at the back of the eye. This results in a blurred image and difficulty with vision. Laser vision correction procedures achieve the same result using slightly different techniques. The excimer laser is used to reshape the cornea, creating the ideal curvature for each eye, to re-focus light onto the retina. The main difference between LASIK and PRK is the location within the cornea where the excimer laser is applied. LASIK changes the shape of the cornea underneath a flap, while PRK changes the shape of the corneal surface.
Why have laser eye surgery?
People seek to correct their vision for many reasons. Professionals and enthusiastic sports players find that glasses or contact lenses can hinder their performance. They find that the results of the laser procedure will make their life easier and allow them to pursue their passion.
Those who are seeking to join the police or defence forces, and require excellent vision without glasses, are also likely to have laser eye surgery. Others may be long term contact lens wearers and find that the lenses or solutions irritating. Some people who wear glasses find they are an impediment in their everyday life. Common complaints include difficulty when it is raining, steaming of lenses when entering warm environments or while cooking, and difficulty seeing the clock or finding glasses when waking up. These are all potential reasons for people to seek laser vision correction.