Corneal collagen crosslinking with LASIK or SMILE is relatively new, and the true beneficial effects, if any, may not be quantifiable or known for some years yet.
In essence, after the cornea has been reshaped (through LASIK or SMILE), vitamin B2(riboflavin) is applied to soak the cornea, and then ultraviolet light is shone on the soaked cornea. The entire crosslinking process adds about 3 minutes to the entire refractive procedure.
We do know that after crosslinking, the cornea becomes stiffer (stronger in a way). There is no other extra effect known to be caused by the crosslinking. The corneal stiffening may help to reduce the risk of regression, and may reduce the risk of ectasia.
However, it is important to remember that regression is not caused by one single factor, and crosslinking may only address one of several factors.
There were some initial concerns that combined corneal crosslinking may affect the predictability/accuracy of laser treatments, but studies so far show that results are equally accurate whether crosslinking was done or not. Some cases get a degree of corneal haze after corneal crosslinking, however, the haze almost always disappears by itself after a while. So perhaps the only real downside to having crosslinking done, when you don’t really need it, is the extra cost.
Finally, all myopic/shortsighted eyes are elongated. But most myopic eyes are not at particular risk for developing post LASIK ectasia. The risk comes mainly from corneas that show subtle signs of pre-existing keratoconus, and sometimes from corneas that are thinned a great deal either because of treatments for very high myopia or pre-existing thin corneas.
