Change in Epithelial Thickness After Corneal Refractive Surgery

Saturday, April 26, 2014: 1:56 PM
Room 150 (Boston Convention and Exhibition Center)
Shaun B. Robinson, MD, Baylor College of Medicine, Houston, TX, USA
Li Wang, MD, PhD, Baylor College of Medicine, Houston, TX, USA
Douglas D. Koch, MD, Cullen Eye Institue, Baylor College of Medicine, Houston, TX, USA

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.