Emmanuel Eric Pazo

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An Analysis of the Influence of Flap Margin Space on Corneal Nerve Regeneration After Femtosecond Laser–Assisted LASIK

Chen Zhang, Zijie Fang, Emmanuel Eric Pazo, Fei Li, Shaozhen Zhao

Journal of Refractive Surgery, 2026 · article · doi:10.3928/1081597x-20251217-01

Ocular surface & dry eye

Abstract

PURPOSE: To investigate the effect of corneal flap margin space width after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) on corneal nerve regeneration using in vivo confocal microscopy (IVCM). METHODS: This study assessed 46 consecutive patients who underwent FS-LASIK surgery. Routine examinations after myopic laser surgery were performed. IVCM was performed before and after surgery to observe the flap margin space and regeneration of the corneal subbasal nerve. The average of corneal flap margin space was calculated. Patients were divided into two groups: the wide-space group (> 20 µm) and the narrow-space group (⩽ 20 µm). Central and peripheral (average of 3-, 6-, and 9-o'clock positions) corneal sensitivity was tested by the Cochet-Bonnet esthesiometer and corneal subbasal nerve regeneration was quantitatively analyzed. RESULTS: Postoperatively at days 1 to 90, the incision edge of the narrow-space group showed a high-density linear structure without obvious epithelial cells filling in the space, and the corneal nerve gradually grew from the outside of the flap through the incision edge to the inside of the flap. In the wide-space group, obvious epithelial cells filling in the space were observed from 1 day postoperatively, and the corneal nerve grew less from the outside of the flap through the incision edge to the inside of the flap. There was no significant intergroup difference in the central corneal nerve fiber length. However, the peripheral corneal nerve fiber length in the narrow-space group was significantly higher at both 30 and 90 days postoperatively. No statistically significant differences were observed between groups in central and peripheral corneal sensitivity. There was no significant difference in spherical equivalent between groups at each time point. CONCLUSIONS: Although the postoperative flap margin space significantly affects corneal nerve regeneration, it does not influence corneal sensitivity or the refractive outcome after FS-LASIK.

Keywords: femtosecond LASIK; corneal nerve regeneration; corneal sensitivity; myopic refractive surgery; epithelial ingrowth; refractive outcomes; in vivo confocal microscopy

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How to cite

Zhang, C., Fang, Z., Pazo, E. E., Li, F., Zhao, S. (2026). An Analysis of the Influence of Flap Margin Space on Corneal Nerve Regeneration After Femtosecond Laser–Assisted LASIK. Journal of Refractive Surgery. https://doi.org/10.3928/1081597x-20251217-01

@article{zhang2026an,
  title = {{An Analysis of the Influence of Flap Margin Space on Corneal Nerve Regeneration After Femtosecond Laser–Assisted LASIK}},
  author = {Zhang, Chen and Fang, Zijie and Pazo, Emmanuel Eric and Li, Fei and Zhao, Shaozhen},
  journal = {Journal of Refractive Surgery},
  year = {2026},
  doi = {10.3928/1081597x-20251217-01},
  url = {https://doi.org/10.3928/1081597x-20251217-01},
}

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