PRK or surface laser was the original form of laser eye surgery in the early 1990s. It is still one of the 3 common forms of corrective laser performed today but it's modern form is quite different from its early predecessor.
One of the main issues with early PRK was haze or scar formation, particularly in higher corrections. Since the mid 2000s, it has become routine to apply a low dose of an anti-haze agent during surgery. This has meant that haze is a very uncommon problem nowadays even in higher corrections.
Another modern change has been the use of lasers instead of manual or chemical methods to remove the top surface skin of the cornea to access the underlying tissues. This theoretically reduces the amount of tissue stress during PRK. Some studies suggest faster healing and less discomfort with this method. Certainly patients do prefer it over the manual method, though it can only be done with the initial PRK and not subsequent corrective lasers.
Modern eyedrop medications and better bandage contact lenses have also reduced the discomfort after PRK compared to the early days. However, one main remaining potential area of improvement is yet to be solved: more rapid healing time. Already novel biologic technologies are in the works to try make PRK healing as rapid as LASIK and SMILE. And who knows, this might mean that PRK, the "old laser" becomes the "new favourite" :)