Small Incision Lenticule Extraction

The advent of the femtosecond (FS) laser has revolutionized the field of laser refractive surgery. Since its inception in 2003, the FS laser has become integral to various procedures, including laser in situ keratomileuses (LASIK). It has paved the way for innovative approaches like FS lenticule extraction (FLEx). Introduced in 2007, FLEx distinguishes itself by relying solely on the femtosecond laser platform, a departure from LASIK, necessitating using 2 platforms. This streamlined approach reduces procedural time and has proven cost-effective for institutions. While LASIK involves the formation of a corneal flap and the subsequent photoablation of the corneal stroma, FLEx shares the initial step of forming a corneal flap but diverges in its approach. In FLEx, there is no ablation of the corneal stroma; instead, the procedure entails intrastromal dissection and extraction of a refractive lenticule. This unique method offers a distinct advantage in refractive surgery, presenting a compelling alternative to traditional techniques. Small incision lenticule extraction (SMILE), an innovative laser refractive procedure, diverges from traditional methods by circumventing flap creation. Instead, it entails forming a small peripheral corneal incision to extract the lenticule. Sekundo et al, in 2008,  initially described intrastromal lenticule extraction by lifting the flap akin to LASIK; however, this technique underwent modification to become SMILE, featuring the extraction of a refractive lenticule through a 2 mm small incision. The absence of corneal flap formation in SMILE was hypothesized to improve corneal biomechanical stability compared to LASIK or FLEx due to minimal disruption of the peripheral collagen networks in the anterior stroma, constituting approximately 60% of the total corneal tensile strength.  Furthermore, the small incision of SMILE was theorized to reduce injury to the subbasal nerve plexus and avoid flap-related complications. Since its first use in 2008, SMILE has gained favor among ocular surgeons and holds the potential to emerge as the standard of care for surgically correcting visual refractive errors. SMILE has garnered recognition as being comparable to FS-LASIK in terms of efficacy, safety, and predictability, making it a preferred choice for the treatment of myopia and myopic astigmatism. The procedure delivers predictable and precise visual acuity and quality, increasing patient satisfaction. However, mastering the SMILE technique poses a steep learning curve for beginners. A step-wise approach is recommended to navigate this learning process effectively, involving observation, wet lab training, and experience with flap-based refractive lenticule extraction (such as FLEx and pseudo-SMILE). This structured learning path aids novice surgeons in comprehending the dynamics of SMILE surgery, mainly focusing on lamellar dissection and the handling of the refractive lenticule. Complications are more likely to arise during the initial learning phase, with the majority attributed to lenticule dissection and extraction challenges. As SMILE gains global popularity, various modifications to surgical techniques have been proposed to facilitate the process of lenticule dissection. The evolving landscape of SMILE surgery underscores the importance of ongoing innovation and refinement in surgical approaches to optimize learning outcomes and minimize complications for practitioners at all levels of expertise.