Frequency-dependent associations of contrast sensitivity and corneal aberrations after SMILE PRO in eyes with high astigmatism.

BACKGROUND

Visual quality after SMILE PRO in eyes with high astigmatism remains incompletely characterized, particularly with respect to contrast sensitivity across spatial frequencies and postoperative anterior corneal aberrations.

METHODS

This prospective cohort study included 160 eyes of 102 patients with manifest astigmatism ≥2.00 D who underwent SMILE PRO using the VISUMAX 800. Patients underwent preoperative and postoperative assessment of visual acuity, manifest refraction, mesopic contrast sensitivity at 1.5, 3, 6, 12, and 18 cycles per degree, and anterior corneal wavefront aberrations calculated for a 6-mm pupil. Follow-up was performed at 1 week, 1 month, and 3 months. Generalized estimating equation models were used to account for inter-eye correlation and to evaluate associations between 3-month visual quality outcomes and preoperative refractive characteristics, intraoperative optical zone diameter, decentration category, and cyclotorsion.

RESULTS

At 3 months, refractive outcomes were stable, with 98.8% of eyes achieving uncorrected distance visual acuity of 20/25 or better. Preoperative astigmatism subgroup was not significantly associated with postoperative total higher-order aberrations, coma, spherical aberration, or contrast sensitivity. A larger intraoperatively selected optical zone diameter was consistently associated with lower postoperative anterior corneal aberrations. Preoperative spherical equivalent was associated with total higher-order aberrations and spherical aberration, while absolute cyclotorsion was associated with coma. Exploratory analyses of contrast sensitivity showed frequency-specific nominal associations with preoperative spherical equivalent, cylinder, and decentration category.

CONCLUSION

At 3 months after SMILE PRO in eyes with high astigmatism, anterior corneal aberration and contrast sensitivity outcomes showed exploratory associations with refractive magnitude and intraoperatively selected optical zone diameter, with additional findings related to cyclotorsion and decentration category. Categorical astigmatism severity was not significantly associated with these outcomes. However, this null finding should be interpreted cautiously because the astigmatism subgroups were imbalanced and relatively few eyes had very high astigmatism. These short-term findings require confirmation in larger comparative studies with longer follow-up.