In general, the visual results of SMILE surgery are similar to LASIK. The majority of the scientific and clinical data compares SMILE to 1st and 2nd generation LASIK surgery results. The studies show that the visual results are better with the modern, 5th generation LASIK lasers than with SMILE. Interestingly, in the US FDA clinical trials, fewer patients achieved 20/20 vision after SMILE than LASIK.

The most common reason for reduced vision after any laser eye surgery is under-correction. The rate of under-correction with SMILE is slightly higher than LASIK; this is especially true when correcting astigmatism prescriptions and happens as often as 1 out of 10 patients that undergo SMILE.

Although it is possible to achieve 20/20 eyesight or better with both procedures, LASIK offers the ability to perform customized ablations using wavefront and topography-guided (5th generation) technologies. This technology is not yet available with SMILE. These customizable techniques can achieve crisper visual quality by smoothing the topographical irregularities that affect visual clarity.

Due to corneal variability, two individuals may have 20/20 eyesight, but this does not mean their vision will be of the same quality. Advanced customized wavefront-guided LASIK offers significant advantages in visual outcomes for individuals with irregular corneal topography, previous laser eye surgery, or high angle kappa.