Over the past two decades, refractive surgery has expanded to include PRK, LASIK and phakic I O Ls. With these new techniques, the range of treatable refractive errors has expanded to include higher degrees of myopia, hyperopia, and astigmatism. The type and degree of refractive error may determine the type of refractive surgery that is most appropriate e.g. for low myopia several options available (e.g. PRK and LASIK), for high myopia (e.g. LASIK and phakic I O Ls .), AK for astigmatism , while PRK , LASIK , and phakic I O Ls . For hyperopia .