Topography-Guided Corneal Crosslinking for Keratoconus: Is It Enough to Treat the Cone?
DOI:
https://doi.org/10.48560/rspo.28285Keywords:
Corneal Cross-Linking, Corneal Topography, Cross-Linking Reagents, Keratoconus, Patient Outcome AssessmentAbstract
INTRODUCTION: Our objective is to report topographic and refractive outcomes in the first year following topography guided corneal crosslinking (TG-CXL) for keratoconus, with special focus given to the morphological changes in the superior, non-treated, corneal stroma.METHODS: Retrospective study. We included patients with progressive keratoconus who underwent TG-CXL: The epithelium was removed using phototherapeutic keratectomy with a 50 µm ablation within a 7.0 mm optic zone, followed by riboflavin application each 2 minutes for 10 minutes, and topography guided irradiation with ultraviolet-A, with treatment energies ranging from 10 to 5.4 J/cm2 and fluence of 10 mw/cm2. Patient data was collected at baseline, 3, 6 and 12 months postoperatively and included maximum keratometry (Kmax), mean anterior keratometry values within 5 points of a 3 mm diameter circle centered at the pupil, in the superior (S index) and inferior (I index) halves of the cornea, central corneal thickness, thinnest point pachymetry, subjective refraction and best corrected visual acuity (BCVA).
RESULTS: Twenty-seven eyes from 24 patients were included. Kmax was significantly flattened at 6 months (-0.92 ± 1.58 D; p=0.011) and 1 year (-0.83 ± 1.64 D; p=0.016) postoperatively. I index decreased significantly at 6 months (-0.81 ± 1.10 D; p=0.002) and 1 year (-0.83 ± 1.11 D; p=0.001), while the S index increased significantly at 6 months (0.93 ± 1.70 D; p=0.016) and 1 year (0.81 ± 1.42 D; p=0.008). There were no significant differences in Kmax (0.16 ± 0.99 D; p=0.457), I index (-0.004 ± 0.60 D; p=0.978) and S index (-0.04 ± 0.99 D; p=0.864) between 6 and 12 months postoperatively. The BCVA improved significantly at 1 year (difference of -0.13 ± 0.14 logMAR to baseline; p<0.001), while there was a significant myopic increase in spherical refractive error (difference of -1.05 ± 2.08 D to baseline; p=0.017).
CONCLUSION: TG-CXL leads to flattening of Kmax and superior corneal steepening at 1 year postoperatively. These keratometric changes seem to stabilize at 6 months. Spherical myopic refractive error increased and BCVA improved during follow-up. These results support TG-CXL as a valuable procedure in progressive keratoconus.
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