One-Year Follow-Up of Changes in Corneal Densitometry After Accelerated (45 mW/cm2) Transepithelial Corneal Collagen Cross-Linking for Keratoconus: A Retrospective Study

PURPOSE The objective of this study is to investigate changes in corneal densitometry after accelerated transepithelial corneal collagen cross-linking (ATE-CXL) for patients with progressive keratoconus (KC). METHODS Seventeen progressive KC patients who underwent ATE-CXL (KC group) were examined and compared against 17 non-KC myopes (control group). For the KC group, corneal topography and densitometry were evaluated preoperatively and at 1, 6, and 12 months postoperatively. Manifest refraction spherical equivalent and best spectacle-corrected distant visual acuity were assessed preoperatively and at 12 months postoperatively. These parameters were also evaluated in the control group. RESULTS Preoperatively, in the KC group, the densitometry values of the total layer over the annular diameters (Φ) 0 to 2 and Φ 2 to 6 mm were 18.47 ± 1.81 and 16.62 ± 1.60, respectively. In the control group, the values were 14.98 ± 1.18 and 13.39 ± 1.33, respectively, significantly lower than those of the KC group (both post hoc P values < 0.001). At postoperative month 12, the densitometry values of Φ 0 to 2 and Φ 2 to 6 mm of the total layer in the KC group were 16.88 ± 1.57 and 15.28 ± 1.40, which were significantly lower than the preoperative values (post hoc P = 0.012 and 0.030, respectively). However, they were still higher than those of the myopes (post hoc P = 0.002 and 0.001, respectively). CONCLUSIONS KC patients have much higher corneal densitometry values than myopes without KC. The KC patients' corneal densitometry values decreased significantly when measured at 12 months after ATE-CXL. However, they remain higher than those of the myopes.