Transient corneal endothelial changes following accelerated collagen cross-linking for the treatment of progressive keratoconus

Purpose: To evaluate the corneal endothelial changes following accelerated collagen cross-linking (CXL) for the treatment of progressive keratoconus. Methods: Thirty-six consecutive progressive keratoconus patients who received accelerated CXL treatment were enrolled in the study. Following de-epithelization, isoosmolar 0.1% riboflavin solution without dextran was instilled every 3 min throughout the 30 min of soaking time before the 5 min of 18 mW/cm(2) UVA irradiation and every 2 min during the UVA irradiation. Corneal specular microscopy was performed on both treated and fellow eyes of each patient preoperatively, in the first week, and in the first, third and sixth month postoperatively. Results: There were significant differences in endothelial cell density (ECD), percentages of hexagonality (6A) and coefficient of variation of endothelial cell area (CV) in the first week and first month postoperatively in the treated eyes when compared to their preoperative values and also to the first week and first month ECD, 6A and CV values of the non-operative eyes. ECD returned to the preoperative values at sixth month whereas 6A and CV returned to the preoperative values at third month. Conclusion: Our results suggested that there may be transient changes in human corneal endothelium following accelerated UVA/riboflavin CXL. Resolution of these changes during the follow-up may indicate a safe recovery. However, the treatment guidelines for accelerated CXL including irradiance level and soaking time should be clearly established to minimize the toxic effects of the treatment.