Small Incision Lenticule Extraction (SMILE) for Hyperopia: Optical Zone Diameter and Spherical Aberration Induction

Area of Science:

• Ophthalmology
• Refractive Surgery
• Corneal Surgery

Background:

• Hyperopic refractive errors present unique challenges for laser vision correction.
• Small Incision Lenticule Extraction (SMILE) is an advanced femtosecond laser procedure.
• Evaluating the efficacy of SMILE in hyperopic corrections is crucial for expanding its application.

Purpose of the Study:

• To assess the effectiveness of optical zone diameter in hyperopic SMILE.
• To analyze the induced spherical aberration changes following hyperopic SMILE.
• To compare these outcomes with conventional LASIK procedures.

Main Methods:

• Prospective study involving 60 hyperopic SMILE procedures using a femtosecond laser.
• Comparison with matched LASIK control groups (6.5-mm and 7-mm optical zones).
• Measurement of achieved optical zone diameter using curvature difference maps at 3 months post-surgery.

Main Results:

• Hyperopic SMILE achieved a larger mean optical zone diameter (6.75 mm) compared to 6.5-mm LASIK (6.61 mm) and was comparable to 7-mm LASIK (6.92 mm) by axial mapping.
• Tangential mapping showed SMILE's achieved diameter (5.03 mm) was similar to 7-mm LASIK (4.96 mm) and larger than 6.5-mm LASIK (4.53 mm).
• Spherical aberration induction was -0.45 μm for SMILE, comparable to 7-mm LASIK (-0.50 μm) and less than 6.5-mm LASIK (-0.69 μm).

Conclusions:

• Hyperopic SMILE demonstrates a larger achieved optical zone diameter than hyperopic LASIK.
• This larger optical zone in SMILE leads to comparable spherical aberration induction to larger optical zone LASIK.
• SMILE offers a viable and effective option for hyperopic correction with favorable optical outcomes.