Thinner, Smoother, Safer – An Introduction to the Evolution of Excimer Laser Flap Making Technology Excimer laser in situ keratomileursis (LASIK) has been in existence for more than 20 years and is a safe and effective treatment for myopia with good stability, safety and predictability. LASIK is a safe and effective treatment for myopia, with good stability, safety and predictability, and is currently the mainstream procedure for myopia. As the name implies, this procedure is characterized by laser cutting under the corneal flap, so the quality of the flap and the cutting surface (i.e., stromal bed) is very important for the postoperative results (especially visual quality)! Looking back at the evolution of the corneal flap making process in our myopic laser department, it is a microcosm of the industry’s development! At the beginning of the department, we used a pneumatic flat-push type corneal knife with a tip labeled 130um, but the actual flap thickness was 160um (Figure 1), which restricted the treatment of some high myopia, and the rough cutting surface made it difficult to guarantee the postoperative visual quality; later, the corneal knife process was improved, and an electric rotary cutter took its place with a tip labeled 110um, but the actual flap thickness was 160um (Figure 1). Later, although there were some small technical improvements, it was difficult to achieve a breakthrough in the process. The emergence of the one-use-plus keratome was a considerable progress, and the thickness of the flap was further reduced (about 100um), and the cutting surface obtained was smooth as never before! (Figure 2) Figure 1 Figure 2 Just when we were marveling at the advances made by the one-use-plus keratome and thinking that this was the pinnacle of the flap-making process, the femtosecond laser was introduced (Figure 3), changing the way we had previously thought of flap-making. It replaced the traditional mechanical corneal knife with the micro-bursting principle of the femtosecond laser, elevating the flap-making process from the “cold weapon era” to the “hot weapon era”! It is no exaggeration to say that it has created a new era, since then, the production of corneal flap has been upgraded from the previous “manual” operation to “tailor-made”! A thinner flap results in a smoother surgical cutting surface, resulting in better visual quality and higher surgical safety! Figure 3 It is believed that with the further improvement of femtosecond laser technology, its application in the field of ophthalmology will be more extensive and deeper!