Long-term Outcomes of Collagen Crosslinking for Early Keratoconus

PURPOSE: To evaluate the long-term outcomes of collagen crosslinking in early keratoconus. METHODS: Thirty eyes of twenty patients with early keratoconus were enrolled. Uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), objective refraction, subjective refraction, corneal topography and pachymetry were assessed before and 3, 6, 12 months and 9 years after performing collagen crosslinking surgery. RESULTS: The patients' mean age was 31.2 [Formula: see text] 5.59 years at nine-year follow-up (range, 25–44 years). The means of preoperative UCVA and BSCVA were 0.57 [Formula: see text] 0.34 and 0.15 [Formula: see text] 0.12 logMAR, respectively, and these values remained stable at the final follow-up (P = 0.990 and P = 0.227, respectively). The mean objective spherical equivalent decreased considerably from –6.00 [Formula: see text] 4.05 D preoperatively to –5.22 [Formula: see text] 3.71 D at the final follow-up (P [Formula: see text] 0.05). The mean subjective spherical equivalent was –4.25 [Formula: see text] 2.87 D preoperatively and this value was stable at the last follow-up (P = 0.92). No considerable difference was found between the post- and preoperative mean objective cylinder values (P = 0.34). The mean subjective cylinder value changed significantly from –4.05 [Formula: see text] 1.85 D preoperatively to –3.1 [Formula: see text] 1.42 D at the final follow-up (P [Formula: see text] 0.05). The mean central corneal thickness was 496.97 [Formula: see text] 45.95 µm preoperatively and this value was stable at nine-year follow-up (P = 0.183). No significant difference was found between the pre- and postoperative mean maximum and mean minimum corneal curvature values (P = 0.429 and P = 0.248, respectively). There were no significant postoperative complications. CONCLUSION: Corneal crosslinking in early keratoconus seems to be a safe procedure that can effectively stabilize UCVA, BSCVA, subjective SE and CCT, while improving objective spherical equivalent.