Compare The Clinical Outcomes Of Small Incision Lenticule Extraction (Smile) Monovison With Laser-Blended Vision By Lasik For Presbyopia Correction

Presbyopia and myopia are prevalent refractive error eye diseases. Both diseases impaired quality of life with blurry vision and glasses-dependent. Refractive surgeries for presbyopia using small incision lenticule extraction(SMILE)
and laser-blended vision (LBV) were employed in recent years.Both surgical techniques use the principle of monovision for correction of presbyopia.Theoretically, LBV provide better depth of field through a mico-monovision protocol by implanting preoperative spherical aberration using MEL 90 excimer laser designed by Carl Zeiss. However, which methods has better outcome haven’t been widely studied. The purpose of this study is to evaluate the effectiveness and stability of the refractive outcome of SMILE and LBV.

 All study procedures were performed under accordance of the Declaration of Helsinki. From Aug 2021 to Dec 2024, patients who came to the clinic for presbyopia correction were enrolled. The inclusion criteria include age over 42 years old and corrected distance visual acuity >=20/25. The exclusion criteria were history of receiving intraocular surgery, corneal or lens opacity, retinal or optic diseases that would interfere the surgical refractive outcomes and abnormal corneal topography results.

Preoperative exam includs subjective and objective refraction measurement, slit lamp, dilated fundus, optic disc and macular exam with optical coherence tomography and corneal topography.Eye dominance was determined with the hole test and an anisometropia tolerance test was performed by using frame glasses with full correction in the dominant eye and +0.5 to +1.5D in the nondominant eye. Binocular distance vision acuity and near acuity were measured
under correction by glasses. After times of adaptation, patients were asked about the feelings when walking around and the target of the nondominant eye would be adjusted accordingly by +0.25D intervals. If the patients could not tolerate any anisometropia, the surgery would not be performed.

There were total of 400 eyes of 200 patients with mean age of 47.8 years in LBV group and 389 of eyes of 194 patients with mean age of 44.6 years in SMILE group. Postoperative biometrics with minimal follow-up duration of 19 days (from 19 to 1215 days) were calculated and analyzed. In LBV group, 97 % of patients could achieve binocular uncorrected distance visual acuity (UDVA) over 0.9 or better; 95% of patients could obtain uncorrected near vision better than J2 and 85% can read J1 or J1+;enhancement rate was 3%. In SMILE group, 95.7 % of patients could achieve UDVA over 0.9 or better; 93.8% of patients could have their target refraction of the dominant eye within 1D spherical equivalent (SE) and the enhancement rate was 2.8%.

In this retrospective comparative study, both LBV and SMILE groups could achieve adequate refractive correction outcome of target spherical equivalent within 1 D and maintain the result in at lear 1 year postoperatively. In presbyopia correction, LBV group can obtain a near correction effect for reading activities in most of the patients which means could read J2 or better. Both LBV and SMILE monovision can achieve adequate far binocular glasses-independent vision better than 0.9. Near glasses-independent vision was obtained in  95% LBV patients. Enhancement rate was higher in LBV group than in SMILE group but without statistically significance. Comparable safety and effectiveness were achieved in either presbyopic refractive procedures.