Corneal Epithelium Thickness And Refractive Changes After Myopic Laser Corneal Refractive Surgery
Published 2022 - 40th Congress of the ESCRS
Reference: FPT03.07 | Type: Free paper | DOI: 10.82333/fdvj-gc28
Authors: Jorge L. Alio Del Barrio* 1 , Mario Canto-Cerdan 2 , Mohamed El Bahrawy 2 , Jorge Alio 2 , Saad Abdulrahman J Al Amri 3
1Cornea, Cataract & Refractive Surgery,VISSUM - Miranza Group,Alicante,Spain;Ophthalmology,Unversidad Miguel Hernandez,Alicante,Spain, 2Cornea, Cataract & Refractive Surgery,VISSUM - Miranza Group,Alicante,Spain, 3Cornea, Cataract & Refractive Surgery,VISSUM - Miranza Group,Alicante,Spain;Ophthalmology,Unversidad Miguel Hernandez,Alicante,Spain;Ophthalmology,Prince Sultan Medical Military City (PSMMC),Riyadh,Saudi Arabia
Purpose
To evaluate the postoperative changes in corneal epithelial thickness and refractive power after femto-laser-assisted in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) for myopia with or without myopic astigmatism, by using an anterior segment optical coherence tomography with integrated placido disk topographer (MS39).
Setting
Methods
Prospective, observational, comparative study. The VisuMAx 500 FS Laser and Amaris 750 excimer laser were used to perform SMILE and LASIK respectively. Central, paracentral and 6 mm epithelial thickness values (ET) were obtained, with the calculation of change of the value of epithelial thickness (CVET). Changes at the refractive power of the epithelium (Epi-Rx) were also evaluated. Repeatability of this new measurement was also analysed (interclass correlation-ICC) for its sphere and cylinder values. Total follow up was 6 months.
Results
77 LASIK eyes were matched with 77 SMILE eyes. Mean SE was -3.92±1.67D for LASIK and -4.02±1.63D for SMILE; (p=0.356). ET parameters showed a significant thickening in both types of surgeries after the 1st month (P<0.001), stabilizing thereafter without significant changes. The CVET showed a greater thickening in SMILE compared to LASIK, being this difference significant at 6 months (P=0.046). CVET correlated positively with the spherical aberration in SMILE for errors ≤4D (P<0.001) and in LASIK for errors >4D (P=0.007). Epi-Rx analysis (ICC >0.70) showed a tendency for the myopization of the refractive component of this layer (-0.11D in SMILE and -0.53D in LASIK), with significant correlation between Epi-Rx and RSM/A in both groups.
Conclusions
Corneal epithelium thickens within the first month after both LASIK and SMILE, although this change seems greater after SMILE. The change in ET values is greater as higher is the induced spherical aberration (and so the targeted SE). This thickening of the corneal epithelium induces the myopization of its refractive power, accounting for a slight undercorrection of the net refractive power change on the treated cornea. To the best of our knowledge, this is the first study that provides a precise value to the refractive change induced by the postoperative corneal epithelium remodelling.