The book ‘The Naked Eye’, written by Dr Michael Lawless and Dr Gerard Sutton, outlines everything there is to know about laser eye surgery. In a chapter written by Dr Lawless (transcript below), he explains the ASLA laser eye surgery procedure.
‘The Naked Eye’, a comprehensive guide to laser eye surgery, is available to order both in paperback and Kindle editions here.
ASLA (Advanced Surface Laser) laser eye surgery
ASLA laser eye surgery – Figure 1
When the first excimer laser was introduced to Australia back in 1991 by Chris Rogers, Peter Cohen and myself, all vision correction procedures were performed on the surface of the cornea. Back then we called it PRK (which stands for Photo Refractive Keratectomy) but as techniques improved it became known as Advanced Surface Laser (or ASLA). Although the majority of vision correction procedures we perform are now LASIK, ASLA still plays an important role. One is not better than the other in terms of outcome or safety. They have different uses and suitability for different patients. When you perform laser vision correction on the surface of the eye you still use an excimer laser but it doesn’t involve creating a flap as in LASIK.
It is a lot simpler for a surgeon to just operate on the surface of the eye compared to creating a flap. We still have to prepare the eye’s surface by removing the epithelium and the tear film layers. During this laser eye surgery procedure procedure, those layers are disrupted with a solution of alcohol and removed, exposing the smooth regular surface of the cornea beneath. (Fig 1)
The next step involves using the excimer laser to reshape the cornea to the required shape for clear vision without glasses or contact lenses. (Fig 2)
ASLA laser eye surgery – Figure 2
You get beautiful results. It is a fantastic procedure and great for someone who has a thinner cornea, but there is definitely more discomfort during the healing process after the surgery.
You can’t see properly for the first few days after your ASLA laser eye surgery procedure and it is usually a couple of weeks before you star t to see clearly. It takes that length of time for your epithelium (front surface of your eye) to re-establish itself on the cornea and to build up to a nice smooth layer again.
ASLA laser eye surgery today
ASLA laser eye surgery is certainly more comfortable than it was ten years ago because we use a bandage contact lens on the surface of the eye and we use Voltaren eye drops as well as pain relief medication. But you have to be prepared for a bit of discomfort. Some people describe it as very scratchy eyes. You feel like you have a grain of sand in your eyes. It varies. One of the staff had it done and she has sinus problems and said it was nothing compared to her sinus problems. Other people say they can barely open their eyes. A lot of it depends on the individual’s pain threshold and what else is going on in their lives.
ASLA is certainly something you get done when you have a little bit of down time, whereas with LASIK you go in and have it done then just go back to work the next day. (With LASIK you’re advised to take the next day off but in most cases you don’t really have to once you have had your post-operative visit and been given the thumbs-up by your surgeon). With LASIK you typically have excellent vision the next morning. We check the vision the morning after your procedure and if you had LASIK you generally have 20/20 vision. With ASLA you would be struggling. There is quite a difference in the immediate result but there is no difference in the long-term result.
While the majority of people are suitable for LASIK, ASLA may be the procedure of choice in certain circumstances, e.g. if your cornea is too thin for LASIK, has any unusual steepness or in certain dry eye conditions. Your doctor will recommend the one that is suited to your eyes and that is going to give you the best result.
ASLA vs LASIK laser eye surgery
Of our patients undergoing laser vision correction on the cornea, the last time I checked it was 89% LASIK versus 11% ASLA. It may have altered slightly since then, but generally in our practice that is what we do. Why does LASIK dominate? Because we have the femtosecond IntraLase method of creating the flap, which makes LASIK a very predictable, safe procedure, and because you have no down-time, instant visual recovery and generally no pain, it is the procedure of choice for the majority of people assuming they are suitable to have a flap.
There are some reasons that preclude you from having LASIK – for example, having a thinner cornea. If you have a very thin cornea, ASLA (Advanced Surface Laser) comes into its own because you have all that extra tissue to work with that you would have allocated to a flap in LASIK. ASLA also has implications for people with ocular surface issues such as dry eye, so there are certain patients that are more suited to it.
To order your copy of The Naked Eye by Dr Michael Lawless and Dr Gerard Sutton, click here.