Abstract
PurposeThe aim of this study is to compare the long-term effects of transepithelial corneal crosslinking with two continuous cycles of iontophoresis (EI-CXL) and conventional corneal crosslinking (C-CXL) in adults with progressive keratoconus.MethodsA retrospective analysis was conducted in adults who underwent C-CXL or EI-CXL between 2013 and 2015. Visual acuity, corneal tomography, anterior segment optical coherence tomography, in vivo corneal confocal microscopy (IVCM), and endothelial cell count (ECC) were performed preoperatively and 5 years postoperatively.ResultsSixty-eight patients with a mean age of (24.3 ± 3.8) years were included, 34 for each group. After CXL, UCVA or BCVA remained stable, while the spherical diopter, cylinder diopter, spherical equivalent, and Kmax significantly decreased at 1, 2, and 3 years in both groups than baseline (P < 0.05). No significant differences were found in any refractive or tomographic parameters as well as the minimal corneal thickness between groups during follow-up. At 5 years, Kmax was slightly higher in EI-CXL group (58.16 ± 6.28) than that of C-CXL group (57.46 ± 4.98). At 3 and 5 years, the minimal corneal thickness in C-CXL group was still significantly lower than baseline (P < 0.05). IVCM demonstrated the demarcation zone at a mean depth of (302.0 ± 41.7) μm after C-CXL, and at (251.2 ± 28.1) μm after EI-CXL (P < 0.001). Keratocyte repopulation was detectable at all follow-up timepoint in both groups. Postoperative complications including progression were recorded in 6 patients (11.7%) after C-CXL and 3 patients (8.8%) after EI-CXL. ECC remained stable in both groups.ConclusionEI-CXL showed approximate efficacy with C-CXL in stabilizing progressive keratoconus in adults. EI-CXL has the potential to be a preferable transepithelial protocol.
Highlights
MethodsKeratoconus (KC) has long been considered as a progressive, non-inflammatory corneal thinning and ectasia with reduced biomechanical stability, which may lead to severe visual impairment in young and even pediatric patients
To reduce the risk of postoperative complications, epithelium-on(epi-on) protocols assisted by iontophoretic delivery or transepithelial riboflavin were brought into sight and were considered by some researchers to be a better choice
Some study demonstrated that iontophoresis-assisted CXL could achieve the same clinical result as standard CXL [21], most evidences have demonstrated inferior results of standard protocol of transepithelial CXL when compared to the conventional epi-off protocol
Summary
Keratoconus (KC) has long been considered as a progressive, non-inflammatory corneal thinning and ectasia with reduced biomechanical stability, which may lead to severe visual impairment in young and even pediatric patients. During CXL, riboflavin interacts with ultraviolet-A light to create crosslinking of protein fibrils followed by formation of interchain disulfide bonds, arresting the progression of corneal ectasia by increasing the biomechanical stability of the cornea. CXL has been considered as one of the standard treatments of progressive keratoconus worldwide. Postoperative complications using standard epi-off protocol [2,3,4,5], such as corneal haze, sterile corneal infiltrates, recurrent erosion syndrome, have been reported and should be taken into consideration. To reduce the risk of postoperative complications, epithelium-on(epi-on) protocols assisted by iontophoretic delivery or transepithelial riboflavin were brought into sight and were considered by some researchers to be a better choice
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