Corneal Higher-Order Aberrations of the Anterior Surface, Posterior Surface, and Total Cornea After SMILE, FS-LASIK, and FLEx Surgeries
The femtosecond laser has been applied to create the corneal flap in the established laser-assisted in situ keratomileusis (LASIK) procedure ever since 2003. It was further introduced in the femtosecond laser lenticule extraction (FLEx) procedure because of the high predictability and milder corneal healing responses than the excimer laser. However, the corneal flap is still needed, and it may induce higher-order aberrations (HOAs). Corneal HOAs were associated with night vision disturbance, glare, halo, and degraded optical quality. Many efforts have been made to reduce corneal HOAs to obtain premium postoperative visual qualities.
Small incision lenticule extraction (SMILE) is a new procedure that removes the refractive lenticule with an incision ranging from 2 to 5 mm, and flap-induced aberrations are subsequently avoided.4 Although previous studies investigated the changes of corneal HOAs after the SMILE procedure, they mainly focused on the anterior corneal HOAs or total corneal HOAs; whether the SMILE procedure has an effect on posterior corneal HOAs is still not well understood, and only a few studies have systematically compared the anterior, posterior, and total corneal HOAs among SMILE, femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and FLEx.
The posterior corneal HOAs are important for the evaluation of corneal biomechanical responses and could provide valuable information in determining the cause of poor visual quality after corneal refractive surgery. Hence, we performed the investigation on the characteristics of the anterior corneal HOAs, posterior corneal HOAs, and total corneal HOAs in myopic eyes before and after FS-LASIK, FLEx, and SMILE surgeries to have a better understanding of postoperative visual qualities.