Purpose: The aim of this long-term retrospective study was to prove a long-term halting effect of riboflavin and UVA-induced collagen cross-linking in progressive keratoconus.
Methods: Since 1998, within an ethics-committee-approved study (EK 310 499), patients with progressive keratoconus and a minimal corneal thickness of 400 microm have received cross-linking treatment. An increase of the maximum K-value by > or =1 D within the previous year, a patient's statement of deteriorating visual acuity, or the need for a new contact lens fitting more than once in 2 years was considered progression. The maximum follow-up time was 7.5 years. At the first examination and all follow-up examinations, refraction, best corrected visual acuity, corneal topography, and ultrasound pachymetry were recorded.
Results: The analysis included 153 eyes of 111 patients, with a minimal follow-up of 12 months. Keratectasia significantly decreased in the 1st year by 2.29 D, in the 2nd year by 3.27 D, and in the 3rd year by 4.34 D. Visual acuity improved significantly in at least one line or remained stable (i.e., no line loss) in the 1st year in 48.9% and 23.8%, respectively; in the 2nd year in 50.7% and 29.6%, respectively; and in the 3rd year in 60.6% and 36.4%, respectively. We saw no severe side effects. Three patients showed continuous progression of keratoconus and received cross-linking treatment again. Despite the small number of patients with a follow-up longer than 3 years, therefore limiting the statistical assertions, our results indicate long-term stabilization or improvement after collagen cross-linking.
Conclusion: With regard to the size of our cohort and the follow-up time, no comparable data have been published in the literature. The results of this study indicate that collagen cross-linking appears to be an effective therapeutic option for progressing keratoconus. Besides the clinical benefit, there are enormous economic and psychosocial benefits. Cross-linking is an outpatient, minimally invasive, cost-effective treatment involving minimal effort for the persons concerned.