Change in Epithelial Thickness After Corneal Refractive Surgery
Narrative Responses:
Purpose
Using anterior segment optical coherence tomography to characterize changes in corneal epithelial thickness that occur after myopic LASIK or PRK
Methods
In two prospective observational case series, 5 patients (10 eyes) received femtosecond LASIK and 7 patients (14 eyes) received PRK to correct myopia. In the LASIK group, epithelial thickness was measured preoperatively and at 3 months postoperatively using anterior segment SD-OCT (Optovue RTVue-100, Optovue Inc., Fremont, CA). In the PRK group, epithelial thickness was measured preoperatively and at 1, 3, and 6 months postoperatively using the same OCT device. The change in epithelial thickness was calculated as the difference between central epithelial thickness measurements before and after surgery in each group. (Note: Patients are still being actively enrolled/analyzed).
Results
Mean preoperative spherical equivalent refraction was -4.56 +/- 2.36 diopters (D) (range: -0.88 to -7.63 D) in the LASIK group and -4.71 +/- 2.33 D (range: -1.25 to -7.5 D) in the PRK group. Preliminary data show thickening of the central corneal epithelium at 3 months after myopic LASIK from 50.43 +/- 2.89um to 55.84 +/-2.20um (n=10, P<.05) and after PRK from 50.00 +/- 1.66um to 59.08 +/- 1.10um (n=4, P<.05).
Conclusion
These preliminary data demonstrate thickening of the central corneal epithelium 3 months after both myopic LASIK and PRK. Thickening of the central epithelium may be a compensatory response to thinning of the underlying stroma with myopic ablation, in some small measure counteracting the myopic effect of the ablation.