Abstract
Purpose: To monitor central thickness changes prior to corneal collagen cross-linking combined ultraviolet A irradiation, using iso-osmolar riboflavin 0.1%. Method: Corneal thickness was measured pre-operatively before epithelial removal. Corneal thickness following epithelial debridement was calculated via subtracting 50 mu m. Iso-osmolar riboflavin 0.1% was instilled into the eye every two minutes for ten minutes. Corneal thickness before and after instillation of iso-osmolar riboflavin was compared using Wilcoxon SPSS test. Results: 34 eyes of 17 patients were included in this study. The mean spherical refractive error for all participants was -2.14 +/- 1.95 D and the mean astigmatism was -1.35 +/- 1.04 D. Measured pachymetry was found significantly higher than calculated pachymetry for all participants. In female subjects, the difference between calculated and measured pachymetry was not statistically significant, when bed hydration was and was not performed, p-values were 0.508 and 0.93 respectively. In male subjects, the difference between calculated and measured pachymetry was statistically significant for all the eyes. Conclusion: Iso-osmolar riboflavin can cause a temporary increase in corneal thickness. However, when corneal swelling is desired in thin corneas, use of hypo-osmolar riboflavin may be more effective in preventing any subsequent damage.