Epithelial-Island Corneal Crosslinking in the Treatment of Progressive Keratoconus Patients with Thin Corneas: 2-Year Visual, Refractive, Keratometric, Tomographic, and Aberrometric Outcomes.

Abstract

Objectives: To evaluate the visual, refractive, tomographic, and aberrometric outcomes of epithelial-island corneal collagen crosslinking (CXL) treatment in halting progression in keratoconic eyes with thin corneas.

Materials and methods: We retrospectively reviewed the charts of consecutive patients with advanced keratoconus who had a thinnest corneal thickness (TCT) of <380 μm as measured by anterior segment optic coherence tomography and underwent epithelial-island CXL. The procedure involved tomography-guided customized epithelial debridement, followed by corneal saturation with iso-osmolar and hypo-osmolar riboflavin solutions and ultraviolet-A irradiation (30 min, 3.0 mW/cm²). Best spectacle-corrected distance visual acuity (CDVA), manifest refraction (MR), slit lamp biomicroscopy, corneal tomography, corneal aberrometry, and endothelial cell count (ECC) were evaluated before CXL and at postoperative months 12 and 24.

Results: The study included 10 eyes of 9 patients with a median age of 29.5 (range, 17-51) years. The median postoperative follow-up time was 24.0 (12.0-108.0) months. The median preoperative TCT was 324.0 (232.0-380.0) μm. Preoperatively, the median CDVA was 1.00 (0.70-1.80) logarithm of the minimum angle of resolution, MR spherical equivalent was -18.00 (-25.00 to -6.00) diopters (D), maximum keratometry value was 84.75 (59.80-99.00) D, vertical coma was -1.068 (-6.428 to 0.613) D, and ECC was 2568 (2021-2750) cells/mm². At postoperative year 1 and year 2, there were no statistically significant changes in any of these parameters (all p>0.05). No significant haze, endothelial cell loss, or any other clinically significant adverse event was encountered in any of the eyes.

Conclusion: Epithelial-island CXL seems to be an effective alternative treatment modality in halting progression in keratoconic eyes with thin corneas. Further studies with a longer follow-up and a larger sample size would help to establish the long-term safety and efficacy of this treatment modality.