Effect of the retention ring-assisted continuous application of riboflavin in pulsed-light accelerated corneal collagen cross-linking on the progression of keratoconus

BACKGROUND: To investigate the efficacy and safety of the retention ring-assisted continuous application of 0.1% riboflavin in pulsed-light accelerated corneal collagen cross-linking on the progression of keratoconus. METHODS: The medical records of 20 eyes of 18 patients with progressive keratoconus who received collagen cross-linking at Seoul National University Hospital were retrospectively reviewed. Isotonic 0.1% riboflavin was continuously applied for 10 min using an 8.0-mm retention ring before the irradiation and accelerated cross-linking was applied with 30-mW pulsed-ultraviolet light at a wavelength 365 nm for eight minutes (1 s on/1 s off; 30 mW/cm(2), cumulative dose of 7 .2J/cm(2)) without further intermittent application of riboflavin. Visual acuity, refractive error, topographic index, corneal thickness, and endothelial cell density were evaluated before the operation and at 1, 3, 6, and 12 months. RESULTS: The best corrected visual acuity in logMAR improved from preoperative 0.43 to 0.17 in 12 months (p = 0.050). Maximum keratometry decreased from 51.8 D to 50.4 D at 6 months (p = 0.015) and 50.1 D at 12 months (p = 0.0003). Astigmatism decreased from preoperative 5.5 D to 4.1 D at 12 months (p < 0.0001). Thinnest corneal thickness decreased at three and 6 months but recovered in 12 months (p > 0.05). Endothelial cell density decreased at postoperative 1 month (p = 0.02) but gradually recovered in 12 months (p > 0.05). CONCLUSIONS: Retention ring-assisted continuous application of riboflavin for 10 minutes in pulsed-light accelerated cross-linking is a comparably safe and effective treatment for halting the progression of keratoconus in 12 months when compared to outcomes of the standard Dresden protocol shown in previous reports. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12886-019-1085-2) contains supplementary material, which is available to authorized users.