Analysis of visual, refractive, topographic and aberrometric changes in different uncommon accelerated cross-linking protocols in keratoconus: A 12 month follow-up

Abstract

To describe the visual, refractive, topographic and aberrometric outcomes of six different accelerated cross-linking (ACXL) protocols in progressive keratoconus (KC) at 12 months. This observational retrospective study included 62 eyes of 49 patients with progressive KC that received one of the following accelerated cross-linking protocols: Group I (8 patients, 5.4 J/cm 2, 15mWx12min, pulsed), Group II (11 patients, 5.4 J/cm 2 , 6mWx15min, continuous), Group III (16 patients, 5.4 J/cm 2 , 9mWx10min, continuous), Group IV (13 patients, 5.4 J/cm 2 , 30mWx6min, pulsed), Group V (8 patients, 7.2 J/cm 2 , 15mWx16min, pulsed) and Group VI (6 patients, 7.2 J/cm 2 , 30mWx8min, pulsed). Best corrected visual acuity (BCVA), sphere, refractive cylinder, spherical equivalent (SE), maximum keratometry (Kmax), mean keratometry (Km), flat keratometry (K1), steep keratometry (K2), thinnest pachymetry, total aberrations, high order aberrations (RMS-HOA), spherical aberration, coma and trefoil were studied previously and at 12 months. Intragroup and intergroup statistical analysis was performed. Postoperative complications were noted. 11 patients were females(22,45%) and 38 males(77,55%). Improvement in the BCVA was observed in all groups (P > 0.05). Kmax reduced in all patients and was statistically significant in groups II (p = 0.041), III (p = 0.017), IV (p = 0.018) and V (p = 0.018). Flattening of the Km was significant in groups II (p = 0.028), IV (p = 0.008) and V (p = 0.028), as well as the K1 in groups IV(p = 0.01) and V(p = 0.028) and K2 in group IV(p = 0.036). There was no significant difference in the thinnest pachymetry in any of the groups. Total aberrations, RMS-HOA, spherical aberration and coma reduced in all groups with statistical significance in Group V (P = 0.016). Two patients in Group I had anterior stromal scarring and one patient in Group V presented an unexpected overflattening. Progression was noticed in one patient in Group II. Accelerated CXL protocols included in this study can be considered effective and safe procedures in stopping the progression of keratoconus at 12 months. Improvement in BCVA and wavefront analysis is observed, but results are limited by the number of patients. Caution should be taken when applying high radiance and long duration protocols to prevent undesirable events.