Epithelial Remodelling After Epithelium-off Continuous Accelerated Corneal Collagen Cross-linking in Progressive Keratoconus

Abstract

Background: To analyse regional corneal epithelial and stromal remodelling after epithelium-off (epi-off) continuous accelerated corneal collagen cross-linking (CXL) for keratoconus (KC).Methods: In this retrospective study, 20 patients (33 eyes) who were treated with epi-off continuous accelerated CXL (KXL system; Avedro, Inc., Waltham, MA, USA). All treatments were performed with ultraviolet-A (UVA) (energy, 7.2 J/cm2; irradiance, 30 mW/cm2), using continuous (4 min) illumination. The postoperative changes in corneal biometric and visual outcomes were compared. The corneal thickness changes were evaluated using anterior segment optical coherence tomography (Optovue). All patients were followed up for 12 months postoperatively.Results: Uncorrected distance visual acuity significantly improved from 1.06 ± 0.49 logarithm of the minimum angle resolution (logMAR) to 0.71 ± 0.37 logMAR at 3 months after epi-off continuous accelerated CXL (p<0.001). The corneal epithelial thickness changes were significant in the inner nasal at -1.48 ± 3.65 µm (p=0.024), -1.76 ± 4.21 µm in the inner superior-nasal (p=0.024), -1.52 ± 4.02 µm in the inner superior (p=0.046), -1.97 ± 4.57 µm in the inner superior-temporal (p=0.018), -2.12 ± 4.46 µm in the outer inferior (p=0.014), -2.15 ± 4.82 µm in the outer inferior-nasal (p=0.022), -1.73 ± 4.45 µm in the outer temporal (p=0.019) at 6 months after epi-off continuous accelerated CXL.Conclusions: Significant regional epithelial remodelling occurs after epi-off continuous accelerated CXL; a more regular corneal thickness profile and keratometric variations were observed after treatment.