Efficacy, Safety, and Outcomes following Accelerated and Iontophoresis Corneal Crosslinking in Progressive Keratoconus

Abstract

Purpose: To investigate the outcomes of accelerated (A-CXL) and iontophoresis (I-CXL) corneal crosslinking in a large retrospective cohort with progressive keratoconus. Methods: This retrospective observational cohort study included consecutive patients treated by A-CXL (9 mW/5.4 J/cm2) or I-CXL with a minimal follow-up of 12 months. Visual acuity, manifest refraction, topography, specular microscopy, and corneal optical coherence tomography (OCT) were evaluated at baseline and at the last visit. Progression was defined as an increase in the maximum topographic keratometry (Kmax) of 1D. Results: 302 eyes of 241 patients with a mean age of 25.2 ± 7.5 years were included from 2012 to 2019: 231 and 71 eyes in the A-CXL and I-CXL groups, respectively. The mean follow-up was 27.2 ± 13.2 months (maximum: 85.7 months). Preoperatively, the mean Kmax was 51.8 ± 4.0D, with no differences between groups. Mean topographic measurements and spherical equivalent remained stable during the follow-up. At the last visit, CXL failure was reported in 60 eyes (19.9%): 40 (14.7%) versus 20 (28.2%) in A-CXL versus I-CXL, respectively, p = 0.005. The likelihood of progression after CXL was significantly higher following I-CXL: RR = 1.62, CI95 = [1.02 to 2.59], p = 0.04. Demarcation line presence at 1 month was positively correlated with higher efficacy of CXL, p = 0.03. No endothelial damage was reported, especially in 51 thin corneas (range = 342–399 µm). Conclusions: A-CXL seems more effective than I-CXL in stabilizing keratoconus; this is to be taken into account when a therapeutic indication is posed according to the aggressiveness of the keratoconus.

Identification of the immune-associated characteristics and predictive biomarkers of keratoconus based on single-cell RNA-sequencing and bulk RNA-sequencing

“…The treatment of KC varies depending on the disease severity and progression. In the early stage, KC can be controlled through contact lenses and corneal collagen cross-linking ( 27 ). As the disease progresses, it can only be controlled through corneal transplantation ( 11 ).…”

Corneal collagen cross-linking in patients with keratoconus from the Dresden protocol to customized solutions: theoretical basis

“…Faster: Accelerated CXL At the same time, so-called accelerated UV treatment protocols have been developed to reduce UV irradiation times [43] . These procedures are based on Bunsen Roscoe's law of reciprocity [44] , according to which the irradiation intensity is increased, up to 45 mW/cm 2 , to reduce the time of the irradiation phase, keeping the total energy applied constant [43] . Various authors have expressed doubts about the safety of these protocols, both for possible damage related to the instantaneous UV intensity applied and for the rapid oxygen consumption that occurs [45][46][47][48][49] .…”

“…The parameters of the Dresden protocol (intensity and duration of UV irradiation) were established heuristically considering total energy 5.4 J/cm 2 , the maximum fluence value that the cornea can tolerate [77][78][79] . Through the Bunsen-Roscoe law of reciprocity (year 1839) [44] it is possible to calculate the intensity to be delivered and the time of exposition to UV ray by knowing the fluence received by the biological target (Figure 1). Starting from the fluence of 5.4 J/cm 2 , in the Dresden protocol the treatment parameters were set at 3 mW/cm 2 of UV-A intensity for a total time of 30 minutes.…”

Refractive and cataract surgery beyond VISION2020

“…For patients developing ectasia after refractive surgery, corneal crosslinking (CXL) is fortunately an option, and the continuous development of the technique may eventually end up with an efficient option for an epithelium-on procedure. The iontophoresis principle has, however, recently been found inferior to standard CXL[ 3 ] but may be improved, and new developments in penetration enhancers may allow the patient to avoid pain and slow visual recovery after the standard epithelial-off CXL. [ 4 ] In refractive surgery, simultaneous SMILE® surgery and CXL, named SMILE Xtra, seem to reduce the already low incidence of ectasia further.…”