Long-term Outcomes of Collagen Crosslinking for Early Keratoconus

Abstract

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 $\pm$ 5.59 years at nine-year follow-up (range, 25-44 years). The means of preoperative UCVA and BSCVA were 0.57 $\pm$ 0.34 and 0.15 $\pm$ 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 $\pm$ 4.05 D preoperatively to -5.22 $\pm$ 3.71 D at the final follow-up (P $<$ 0.05). The mean subjective spherical equivalent was -4.25 $\pm$ 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 $\pm$ 1.85 D preoperatively to -3.1 $\pm$ 1.42 D at the final follow-up (P $<$ 0.05). The mean central corneal thickness was 496.97 $\pm$ 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.

Keywords: Collagen Crosslinking; Keratoconus; Cornea.