One complication of LASIK surgeries, which are used to treat regular myopia, is post-LASIK keratectasia. During LASIK surgery, the cornea is weakened, because of the creation of an open flap and the removal of tissue by the laser. Thus, the cornea starts bulging and thinning exactly the same way that can be observed in keratoconus.
Most frequently, given the lack of available alternatives, surgeons tend to recommend crosslinking for the treatment of post-LASIK keratactasia. In this very specific case, CISIS / MyoRing keratoplasty is, however, clearly the first choice of treatment.
While Crosslinking can stop the progression of a “normal” keratoconus, this does not apply to post-LASIK keratectasia in the same way. The difference in therapy options is caused by the flap which is created during LASIK treatment and which does not heal completely anymore. Even after 8 - 10 years, the flap can simply be lifted with a spatula. Thus, the free flap does not fully contribute to the biomechanics anymore. Merely the remaining fraction of the cornea under the flap (residual stromal bed = anatomic corneal thickness without the thickness of the flap) adds to the cornea’s stability. However, during Crosslinking, mainly the anatomic frontal section of the cornea, in the case of post-LASIK keratectasia the free flap, is stiffened. This does not make much sense since the residual stromal bed is practically not treated. Thus, MyoRing implantation into the stromal bed is, in fact, the only reasonable therapy for stopping the progression of post-LASIK keratectasia.