Comparison of Myopic Small Incision Lenticule Extraction (SMILE) With VISUMAX 500 Versus VISUMAX 800 Platforms

Comparison of Myopic Small Incision Lenticule Extraction (SMILE) With VISUMAX 500 Versus VISUMAX 800 Platforms

Small incision lenticule extraction (SMILE) procedure is a well-known procedure for the correction of myopia. The purpose of this research study is to compare the two SMILE procedures with different laser platforms (VISUMAX 500 and VISUMAX 800) used for the correction of short-sightedness. The VISUMAX 800 and VISUMAX 500 perform the same procedure, but the VISUMAX 800 is a newer platform. This study is being done to see if the newer VISUMAX 800 provides the same or better results than the VISUMAX 500.

Surgical correction of refractive errors is widely performed. Small incision lenticule extraction (SMILE) is a flapless refractive procedure introduced in 2011 for the treatment of myopia and myopic astigmatism. In this procedure, a stromal lenticule is created within the cornea using a femtosecond laser and extracted through a small incision (2.0-5.0 mm). The procedure involves docking, femtosecond laser application, lenticule dissection from the surrounding stroma, and lenticule extraction.

The VisuMax 800 femtosecond laser system has recently been introduced and incorporates several technical advancements compared with the previous VisuMax 500 platform, including a faster 2-MHz laser frequency, a centration guidance system (CentraLign), a cyclotorsion compensation system (OcuLign), separate laser and microscope arms, and heads-up docking. Early reports of SMILE performed using the VisuMax 800 have demonstrated excellent visual and refractive outcomes that appear comparable to those reported with the VisuMax 500 femtosecond laser. However, limited data are available directly comparing the two platforms across multiple clinical, biomechanical, molecular, and subjective outcome measures.

This randomized controlled contralateral-eye study will enroll 100 patients undergoing bilateral SMILE surgery. In each participant, one eye will be randomly assigned to undergo SMILE using the VisuMax 500 platform and the fellow eye will undergo SMILE using the VisuMax 800 platform. This design allows direct within-patient comparison while minimizing inter-individual variability.

The study aims to compare refractive and visual outcomes, corneal biomechanical changes, tear proteomic profiles, corneal lenticule metabolomic characteristics, ocular surface parameters, patient-reported subjective outcomes, and surgeons' intraoperative experiences between the two platforms.

Assessments will be performed preoperatively (baseline), immediately after surgery, and at postoperative follow-up visits at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months.

Inclusion Criteria:

• Cycloplegic spherical equivalent of >-1.00D
• Refractive cylinder -2.00 D or less; anisometropia <1.00D
• Best spectacle corrected visual acuity (BSCVA) of 6/12 or better in both eyes
• Spherical or cylindrical error has progressed at -0.50 D or less per year from date of baseline measurement in both eyes
• Contact lens wearers must have removed contact lenses at least 2 weeks before the baseline measurement
• No evidence of irregular astigmatism on corneal topography in both eyes

Exclusion Criteria:

• Progressive or unstable myopia and/or astigmatism
• Clinical or corneal topographic evidence of keratoconus
• Residual, recurrent or active ocular disease such as uveitis, severe dry eyes, severe allergic eye disease, glaucoma, visually significant cataract, and retinal disease
• Previous corneal surgery or trauma within the corneal flap zone
• Patent corneal vascularization within 1 mm of the corneal flap zone
• Taking systemic medications likely to affect wound healing, such as corticosteroids and antimetabolites
• Systemically immunocompromised or systemic disease likely to affect wound healing, such as diabetes, connective tissue disease, and severe atopy; pregnant or nursing