How is SMILE (Small Incision Lenticule Extraction)?

SMILE (Small Incision Lenticule Extraction) is a laser-based treatment for myopia and represents a significant advancement in refractive surgery. This technique offers excellent efficacy with minimal side effects, achieving highly effective correction of myopia. Generally, candidates for SMILE surgery should have a myopic refractive error of at least −6.00 diopters (D) to minimize potential complications. Let’s explore how SMILE works.

How Does SMILE Work?

SMILE represents the highest level of laser corneal refractive surgery and marks a major breakthrough over earlier techniques. Previously, most femtosecond lasers used in LASIK procedures were limited to creating a corneal flap, requiring subsequent combination with an excimer laser to achieve refractive correction. In contrast, SMILE utilizes the femtosecond laser exclusively throughout the entire procedure: first, it creates a precisely shaped interface at a relatively deeper corneal stromal layer—defined by specific diameter and curvature—and then, at a slightly more superficial layer, it creates another interface with a larger diameter and matching curvature. The peripheral edges of these two interfaces intersect, forming a lenticular (lens-shaped), thin corneal tissue layer within the intrastromal plane. This lenticule is then manually extracted using specialized instruments—effectively achieving the same refractive effect as excimer laser ablation.

This technique employs only 10–15 seconds of pulsed femtosecond laser energy and is known as “FLEx” (Femtosecond Lenticule Extraction). Currently, most commercially available femtosecond laser systems in corneal refractive surgery serve solely to replace the mechanical microkeratome for flap creation. After flap creation, an excimer laser is still required to ablate part of the underlying corneal stroma, thereby reducing corneal curvature (flattening the cornea) to correct myopia.

In contrast, the Carl Zeiss “VisuMax” system accomplishes both flap creation and corneal curvature reduction entirely with the femtosecond laser—marking the first time that corneal refractive surgery has completely eliminated the need for excimer laser technology. Moreover, the VisuMax system extends beyond refractive surgery and supports novel clinical applications such as corneal transplantation.

Precautions

For myopic patients considering SMILE surgery, a refractive error of at least −6.00 D is generally required. The procedure is brief, associated with minimal side effects, demonstrates remarkable efficacy, and boasts a success rate of 99.9%—making it a safe and reliable option.

The above provides a concise overview of SMILE. As one of the most advanced forms of laser corneal refractive surgery, SMILE represents a major milestone in the treatment of myopia. Thanks to its sophisticated technology, it delivers outstanding clinical outcomes. Nevertheless, patients should carefully review relevant preoperative considerations before undergoing SMILE.

We hope this information is helpful. Wishing you good health and happiness!