COMPARATIVE STUDY OF LASIK VS. SMILE ON CORNEAL NERVE RECOVERY

Abstract

Objective

This study compared postoperative corneal nerve recovery following Laser-Assisted in Situ Keratomileusis (LASIK) and Small Incision Lenticule Extraction (SMILE). The main objective was to determine whether differences existed between the two refractive procedures in terms of subbasal nerve density regeneration, corneal sensitivity, and dry-eye–related symptoms during a six-month postoperative follow-up period.

Methods

A randomized controlled trial was conducted at a tertiary care ophthalmology hospital in Khyber Pakhtunkhwa, Pakistan. Eligible adults with myopic refractive errors were randomly assigned to undergo LASIK or SMILE. Standardized surgical protocols were used. Postoperative assessments included in vivo confocal microscopy for nerve density, Cochet–Bonnet aesthesiometry for corneal sensitivity, and Ocular Surface Disease Index (OSDI) scoring for symptoms. Data were collected preoperatively and at 1, 3, and 6 months postoperatively. Statistical comparisons were conducted using repeated-measures analysis of variance.

Results

Both procedures resulted in significant reductions in nerve density and corneal sensitivity at 1 month; however, the SMILE group demonstrated faster nerve regeneration and earlier improvements in corneal sensitivity. By 6 months, the SMILE cohort exhibited significantly higher nerve density and lower OSDI scores compared with the LASIK cohort. Although functional visual outcomes were comparable, the trend favored SMILE in terms of neurotrophic recovery. No vision-threatening complications were observed.

Conclusion

SMILE was associated with superior corneal nerve regeneration, faster sensory recovery, and fewer dry-eye symptoms than LASIK during the early and intermediate postoperative periods. These findings suggested that SMILE may preserve corneal neuroanatomy more effectively, potentially reducing postoperative discomfort and enhancing tear-film homeostasis. The outcomes provide clinically relevant guidance for refractive surgery decision-making within the South Asian population context.