ASLA stands for Advanced Surface Laser. It is really no different to PRK.
PRK was the original term used to mean a laser vision correction on the surface of the cornea without first creating a LASIK flap. PRK was largely superseded by LASIK due to quicker recovery time and no discomfort.
Over time however, PRK has had a resurgence owing to the fact that it is a better procedure in some people and the procedure of choice if the cornea is thin. It has become more sophisticated, with better software algorithms that use modern ablation profiles. This has led to better visual outcomes. As the algorithms have progressed, it was decided to re-name PRK to ASLA.
Some clever marketing has tried to create the impression that it is a new procedure but it it is still really PRK, although on steroids.
ASLA vs LASIK
Long term, there is no difference in results between ASLA and LASIK. ASLA is not an inferior procedure and patients having it are not disadvantaged in any way. It is simply as stated, more uncomfortable and visual recovery takes longer.
In some respects, ASLA is safer as there is no corneal flap to worry about and all its attendant risks such as epithelial ingrowth, striae or dislodgement of the flap.
There is no difference in cost.
How is ASLA performed?
There are numerous ways to perform ASLA. Most commonly, the epithelial surface is removed using a blade, motorised burr or alcohol. Alcohol removal is quicker but there is some suggestion that this may lead to recurrent erosions long term.
The new Schwind Laser that we are using performs transepithelial ASLA, meaning that the epithelium is automatically removed by the laser. This results in a cleaner and more precise result.
Once the epithelial surface is removed, the laser then continuous on to re-shape the surface of the cornea. In the case of someone with myopia (shortsightedness) the laser tends to flatten the central portion of the cornea. In the case of hyperopia (long sightedness), the laser steepens the central cornea instead. The process is similar to a lathe, altering the shape of a piece of wood.
This of course is all done under anaesthetic, which is administered with eyedrops only. That is, there are no injections or needles involved.
At the end of the procedure, a contact lens is placed into the eyes and left there for three days until the new epithelium has grown back.
What happens after the ASLA procedure?
After the procedure, you can go home with antibiotic and anti-inflammatory eye drops.
Review is on the third day after the procedure for removal of the contact lenses. This can be either in our clinic or with your optometrist.
Vision is quite good after a few days but improves over the next few weeks and months.
Eye drops are used for two weeks and lubricants for 6-12 months
How long does ASLA last?
Generally, this correction is permanent. However as we age, our bodies (and eyes) change. This may lead to a change in your need for glasses long term. This can be corrected at a future date with an enhancement using the laser, or if the change is only small, glasses or contact lenses.
Some people do experience regression, which is where some of the original myopia or hyperopia returns. If this occurs, an enhancement can be performed once the regression stabilises.
How do I decide wether to have LASIK or ASLA?
This decision is not one that you need to make yourself, rather your particular set of circumstances will govern which approach is best for you
Long term safety of ASLA
ASLA is generally safer than LASIK although both are safe.This is because less corneal surface is removed with ASLA. With LASIK, the flap is usually around 120 microns in thickness which does not contribute to the structural integrity of the cornea. Hence, corneas that have had ASLA have a thicker residual base with consequent less long term risk of complications