The Percent Volume Altered in Correction of Myopia and Myopic Astigmatism With PRK, LASIK, and SMILE.

Purpose: To determine the volumes altered during photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) correction of myopia and myopic astigmatism.

Methods: The volumes of stromal tissue affected by surgical correction of pure and astigmatic myopia were calculated in this theoretical study for PRK, LASIK, and SMILE treatments. These results were then used to calculate representative values for percent volume altered (PVA) restricted to stromal corneal tissue.

Results: For the same spherical equivalent, there were remarkable differences between the amount of tissue removed between pure and compound myopic corrections. The PVA of LASIK procedures was the largest, whereas the PVA was comparable between PRK and SMILE. PRK had the lowest PVA for low myopic and compound astigmatic corrections and SMILE had the lowest PVA for high myopic and compound myopic astigmatism procedures.

Conclusions: The comparison of volumes of tissue removed and PVA values of different treatment modalities provided in this study may give clinicians an improved understanding about the potential influence of geometrical parameters of those methods on the biomechanics of the cornea. [J Refract Surg. 2020;36(12):844-850.].