Stromal mechanical anisotropy of the SMILE lenticule shows no detectable association with postoperative refractive error.
No association found between corneal lenticule stiffness variation and astigmatism outcome after small-incision lenticule extraction
Stromal mechanical anisotropy of the SMILE lenticule shows no detectable association with postoperative refractive error.
Small-incision lenticule extraction (small-incision lenticule extraction) removes an intrastromal lenticule whose stiffness differs between corneal meridians, producing measurable stromal mechanical anisotropy.
In this prospective consecutive cohort, 282 patients undergoing small-incision lenticule extraction for the correction of myopia or myopic astigmatism were enrolled, and 279 right eyes with complete 3-month follow-up were analyzed.
Refractive outcomes were excellent (spherical-equivalent error + 0.29 ± 0.39 D; 99.3% within ± 1.00 D; attempted-versus-achieved R² = 0.918).
The mean modulus showed only a borderline relation to ΔM (ρ = +0.117, P = 0.050), and the residual astigmatic vector was centred near the origin (ΔJ 0 +0.03 ± 0.15 D, ΔJ 45 -0.02 ± 0.11 D).
Although small-incision lenticule extraction lenticules exhibit reproducible meridional mechanical anisotropy, this property did not translate into detectable axis-specific or magnitude-related refractive error in this cohort.
The concordant null finding in the orthogonal negative control supports the interpretation that no measurable axis-specific signal was present, rather than a meridian-independent analytical artifact.