Postoperative complications of SMILE surgery

Nov 11, 2021 Source: Cainiu Health

Dr. Cui Xin

Introduction

Full femtosecond laser surgery refers to using a femtosecond laser to create two lamellar cuts within the corneal stroma. A lenticule is then extracted through a small incision at the corneal margin, thereby altering the corneal surface curvature to correct refractive errors. However, full femtosecond laser surgery may lead to postoperative complications such as glare. Moreover, excessive thinning of the cornea may compromise its structural integrity, rendering it unable to withstand intraocular pressure and potentially resulting in keratoconus.

The key feature of SMILE (Small Incision Lenticule Extraction) surgery is that the entire procedure is performed exclusively using a femtosecond laser—both corneal flap creation and intrastromal lenticule removal are accomplished with the same femtosecond laser system. Prior to undergoing SMILE surgery, patients must discontinue wearing contact lenses and use antibiotic eye drops as prescribed by their physician. Additional preoperative considerations apply; please consult your ophthalmologist for specific guidance. So, what are the potential postoperative complications associated with SMILE? The following section addresses this question.

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Potential Postoperative Complications of SMILE

SMILE involves using a femtosecond laser to precisely cut two parallel planes within the corneal stroma, creating an intrastromal lenticule. This lenticule is then extracted through a small incision at the corneal periphery, thereby altering the cornea’s surface curvature to correct refractive errors. Potential postoperative issues include glare or halos, especially under low-light conditions. Excessively thin residual corneal tissue may compromise structural integrity, potentially leading to keratoconus. Additionally, some patients may experience transient dry eye symptoms in the early postoperative period. Within the field of refractive surgery, “SMILE” specifically refers to two related techniques: stromal lenticule extraction (SLE) and femtosecond lenticule extraction (FLEx). In SLE, a corneal flap is created first, followed by lenticule removal; in FLEx, no flap is created—instead, the lenticule is extracted through a single, ~4-mm incision. Visual outcomes following SMILE are typically stable and long-lasting.

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Knowledge Extension: Differences Between SMILE and FS-LASIK

1. Safety Comparison

Compared with conventional refractive surgeries, both SMILE and FS-LASIK offer significantly enhanced safety profiles, enabling precise, digitally quantifiable control over ablation location and depth. Theoretically, SMILE’s smaller incision size confers a biomechanical advantage over FS-LASIK’s larger flap. However, real-world clinical evidence—including peer-reviewed publications and news reports—has not demonstrated a statistically significant difference in safety outcomes between SMILE and FS-LASIK.

2. Equipment Requirements

FS-LASIK requires two distinct laser systems: a femtosecond laser for flap creation and an excimer laser for stromal ablation—making the procedure comparatively more complex. In contrast, SMILE is completed entirely with a single femtosecond laser system, eliminating the need for additional instrumentation and reducing overall procedure time. Regarding eligibility criteria: SMILE is approved for myopia ranging from −2.00 D to −10.00 D, whereas FS-LASIK accommodates a broader range—from +6.00 D hyperopia to −12.00 D myopia.

The above outlines potential postoperative complications associated with SMILE surgery. We hope this information is helpful to you.

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Femtosecond Laser Treatment for Astigmatism

Femtosecond laser surgery is one type of surgical procedure for astigmatism correction, which also includes semi-femtosecond and excimer laser surgery. Not all patients with astigmatism are suitable candidates for full femtosecond laser surgery; however, those with astigmatism up to 500 degrees are generally eligible for this procedure. For patients with higher degrees of astigmatism, intraocular lens implantation may be considered to achieve better therapeutic outcomes.