In recent years, the incidence of myopia has been high globally and is exhibiting a rapid upward trend, with projections estimating it will reach 49.8% by 2050. Corneal refractive surgery has become a primary method for correcting myopia, demonstrating significant efficacy and favorable safety. However, studies indicate that overcorrection or undercorrection can occur following refractive surgery. Reports have shown that three months post-SMILE surgery, 20% of eyes had residual refractive errors ≥ 0.50 D, and 6% had errors ≥ 1.00 D. We hypothesize that this may be related to imprecise preoperative refraction, subsequently affecting postoperative visual quality.
Due to limitations in lens manufacturing precision, the widely used increment for sphere correction remains 0.25 D. However, this may prevent some patients from achieving their optimal corrected state. Studies have reported that 95% of individuals are sensitive to diopter changes below 0.25 D, and 44% can distinguish changes smaller than 0.125 D. Other research suggests that adjusting spherical power in 0.05 D increments yields better corrected visual acuity. Furthermore, scholars have reported that 0.05 D precision refraction can significantly improve the red-green balance test rate, enabling myopic patients to achieve better visual quality. Therefore, improving refraction precision could provide patients with superior visual outcomes.
Currently, the Binocular Wavefront Optometry Machine (BWFOM, Ai-Zhitong Medical Technology Co., Ltd., Zhejiang, China) can perform objective and subjective refraction with 0.05 D increments for both sphere and cylinder correction, while also separately measuring higher-order aberrations (HOAs) and lower-order aberrations (LOAs). Given the scarcity of research on the outcomes of 0.05 D refraction for SMILE and FS-LASIK procedures, this study aims to evaluate visual acuity, aberrations, and refractive status in patients following SMILE and FS-LASIK surgery. The primary objective is to investigate whether preoperative 0.05 D precision refraction using the BWFOM can enhance postoperative visual quality for SMILE and FS-LASIK patients.
The diopter is relatively stable (the diopter increases within -0.50D per year for 2 consecutive years);
Age: 18 to 40 years old;
Optimal preoperative corrected visual acuity >= 4.8;
More than 2 weeks for soft contact lenses and more than 3 months for hard contact lenses before surgery
Patients with history of eye surgery and trauma;
Patients with keratoconus tendency;
systemic connective tissue diseases and autoimmune diseases;
Patients with high blood pressure, diabetes and heart disease history;
Parallel
Binocular Wavefront Optometry Machine (BWFOM, Ai-Zhitong Medical Technology Co., Ltd., Zhejiang, China)
DeviceThe 0.05 D refraction group had their infusion rates precisely calibrated using 0.05 D refraction by the Binocular Wavefront Optometry Machine
Postoperative spherical equivalent
It calculated as: SE = Sphere + ½ Cylinder
Postoperative corrected distance visualacuity
Using the standard logarithmic visual acuity chart, with units in logMAR.
Postoperative uncorrected distance visual acuity
Using the standard logarithmic visual acuity chart, with units in logMAR
spherical diopter
Spherical diopter (D) is the unit of measurement for the refractive (light-bending) power of a spherical lens (or the spherical component of a corrective lens) used to correct myopia (nearsightedness) or hyperopia (farsightedness).
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