Correlation of Spectral-Domain OCT Measurements of Corneal Power and Epithelial Remodeling With Mild Myopic Regression After Optimized Femto-LASIK
Narrative Responses:
Purpose
To evaluate and correlate Spectral-domain OCT (SD OCT) changes of corneal power (Cpwr) and epithelial thickness profile after Femto-LASIK for myopia.
Methods
38 eyes undergoing Femto-LASIK with ALLEGRETTO Eye-Q Excimer Laser were randomized for IntraLASFS60 flap in one eye and WaveLighFS200 flap in the contralateral eye. SD OCT-RTVue-100 (6mm Pachymetry+Cpwr scans) was used to evaluate the corneal power and epithelial thickness profile preoperatively, 1 week, 1 month, 3 and 9 months postoperatively. Epithelial thickness maps were generated by segmentation of the images in 8 meridians. The average thickness of the central (2mm), superior and inferior zones (2-5mm) was calculated. Changes in manifest refraction (MRSE) and wavefront refraction spherical equivalent (WRSE) were recorded at 1 week, 1, 3 and 9 months postoperatively.
Results
SD OCT measurements of corneal power gradually increased over 3 months postoperative then stabilized at 9 months (Cpwr was 43.10±1.48D preoperatively, 39.83±2.43D at 1 week, and 39.90±2.47D, 40.19±2.44D and 40.20±1.82D at 1, 3 and 9 months postoperatively). Thinning of the corneal epithelium was noted centrally at 1 week postoperative (53.17±3.07µm preop, 52.11±2.95µm at 1 week and 53.8±4.08µm at 1 month). Statistically significant epithelial thickening was observed at 3 and 9 months postoperatively (56.75±4.90µm and 55.28±5.02µm, p<0.001 and p=0.002 respectively). WRSE were respectively -3.33±1.96D preoperatively, -0.19±0.51D at 1 week,-0.16±0.50D at 1 month, -0.28±0.43D at 3 months and -0.33±0.47D at 9 months postoperatively.
Conclusion
Central epithelial thickening was observed at 3 months and remained stable at 9 months after Femto-LASIK for myopia. SD-OCT corneal power slightly increased at 3 months along with mild myopic regression, then stabilized at 9months, suggesting that epithelial remodeling is the main cause of early myopic regression in optimized Femto-LASIK.