Intraoperative Corneal Thickness Monitoring During Corneal Collagen Cross-Linking With Isotonic Riboflavin Solution With and Without Dextran

Purpose: The aim of this study was to analyze and compare corneal thickness changes during corneal collagen cross-linking procedures performed with isoosmolar riboflavin solution with 20% dextran and without dextran in corneal ectatic diseases. Methods: The patients in this study were analyzed in 2 groups: group 1 receiving riboflavin solution containing 20% dextran and group 2 receiving dextran-free riboflavin solution. Corneal thickness measurements were obtained with ultrasonic pachymetry at 6 different time points: preoperatively and at 0, 15, 30, 45, and 60 minutes after epithelial removal and initiation of ultraviolet A irradiation. Results: Twenty-seven eyes of 27 patients with progressive keratoconus were included in the study. In group 1 (n = 13), the mean preoperative thinnest pachymetric readings were 469.3 +/- 8.5 mu m, which decreased to 423.8 +/- 8.9 mu m after deepithelization and further decreased to 385.9 +/- 10.9 mm at 15 minutes. The corneal thickness assumed a steady course at the 30-, 45-, and 60-minute measurements (378.9 +/- 9.8 mu m, 384.5 +/- 10.5 mu m, and 396.7 +/- 9.4 mu m, respectively). The initial change was statistically significant (P < 0.01). In group 2 (n = 14), the corneal thickness decreased from 459.4 +/- 3.8 mu m to 414.7 +/- 2.6 mu m with deepithelization, after which it increased steadily with the initiation of the dextran-free riboflavin solution. The final measurement in group 2 was 474.1 +/- 9.4 mu mm; the increase at each time point was statistically significant when compared with the previous measurement (P < 0.01). Conclusions: Using isoosmolar riboflavin solution without dextran causes a steady increase in the corneal thickness during the cross-linking procedure, as opposed to riboflavin with dextran. This result might be beneficial in broadening the spectrum of cross-linking indications in patients with thin corneas.