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.
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
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
Parallel
SMILE surgery with Visumax 500
Procedure/SurgeryRoutinely conducted procedure using Visumax 500 laser system for correction of myopia.
SMILE surgery with Visumax 800
Procedure/SurgeryRoutinely conducted procedure using Visumax 800 laser system for correction of myopia.
Visual outcomes
Best-corrected visual acuity (BCVA), Uncorrected visual acuity (UCVA). Refractive outcomes: Nine standard graphs for corneal refractive surgery: Post-operative UDVA versus pre-operative CDVA; Change in Snellen lines from pre-operative CDVA to post-operative UDVA; Change in Snellen lines from pre-operative CDVA to post-operative CDVA; Attempted versus achieved spherical equivalent refraction; Accuracy of post-operative spherical equivalent refraction to target; Stability of spherical equivalent refraction, shown as the trend of mean Spherical Equivalent (SE) at preop, one week, one month, three months, six months, and one year post-operatively; Change in refractive astigmatism; Target-induced astigmatism (TIA) vs. surgically induced astigmatism (SIA); Histogram of refractive astigmatism angle of error. Refractive predictability, which is defined as the proportion number of eyes achieving a postoperative spherical equivalent (SE) within ±1.0 D of the intended target.
Patient-reported intraoperative experiences
The in-house patient questionnaire is used to assess patient-reported subjective intraoperative experiences. Rather than utilizing numerical scoring, it uses qualitative descriptors and binary "Yes/No" responses to evaluate perceived discomfort, fear levels, and visual phenomena-such as light perception loss or image clarity-during specific surgical steps like vacuum suction and lenticule creation. The form also includes a ranking system for identifying the most fearful parts of the procedure and asks patients to compare the experience, including perceived speed, between their right and left eyes.
Patient-reported outcomes
The in-house questionnaire is used to assess patient-reported outcomes. This evaluates postoperative outcomes for SMILE surgery performed on the VisuMax 500 and 800 platforms. Rather than using simple numerical scores, the assessment captures subjective patient experiences through qualitative descriptors and frequency-based scales for symptoms like light sensitivity, dryness, and visual disturbances. It also identifies specific environmental triggers, such as lighting conditions, and monitors the functional impact of surgery on daily activities like night driving.
Surgeon experience
The Surgeon Questionnaire evaluates the intraoperative technical performance and early postoperative outcomes of SMILE procedures. Rather than relying on a single numerical score, it utilizes a combination of binary "Yes/No" indicators for surgical complications and descriptive scales to grade tissue adherence and ease of lenticule extraction.
Ocular Surface Disease Index (OSDI)
The Ocular Surface Disease Index (OSDI) is a 12-item questionnaire used to assess the symptoms of ocular irritation. The score ranges from 0 to 100. Higher scores indicate more severe ocular surface disease and a worse outcome.
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