Laser in situ keratomileusis (LASIK) is the most frequently performed corneal refractive procedure.
LASIK can reduce refractive error and improve uncorrected visual acuity, but several problems still must be resolved regarding postoperative visual function.
The retreatment rates for residual overcorrection, undercorrection, induced astigmatism and visual dysfunction due to higher order aberrations following LASIK ranges widely from 5% to 37.9%.
The most commonly used technique for LASIK retreatment is flap relift or flap recutting. However, complications such as buttonhole creation, post-LASIK dry eye syndrome, thin residual stromal bed, and the inability to identify the flap edge can limit surgical options for retreatment
In addition, relifting an old flap increases the risk of epithelial ingrowth, flap tear, striae, and diffuse lamellar keratitis. To avoid these complications, photorefractive keratectomy (PRK) could be used
Transepithelial PRK (tPRK) is a technique where the epithelium is removed using excimer laser PTK prior to application of the stromal refractive treatment.
More recently, a novel treatment modality utilizing excimer epithelial removal using a population-based epithelial profile rather than PTK epithelial removal has become available on the SCHWIND Amaris platform termed transepithelial all surface laser ablation (ASLA).