The key factor that defines PTK is that it provides medical benefits rather than just improving eyesight. The problems that PTK can help with are associated with diseases of the cornea whereas PRK, LASEK and LASIK are more related to correcting refractive issues, i.e., removal of glasses.

So when comparing PTK with the three other procedures, it is clear that PTK is more medically beneficial compared to cosmetically beneficial as seen with the others.

An example of a disorder that PTK can resolve is corneal dystrophy whereas examples of issues that can be sorted with PRK, LASIK or LASEK include myopia and astigmatism.