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Purpose : To compare the outcomes of epithelium-off pulsed accelerated corneal cross-linking (ACXL) and trans-epithelial pulsed accelerated corneal cross-linking (Trans-ACXL) in progressive keratoconus.
Methods : In total, 69 eyes (54 patients) with progressive keratoconus were subjected to ACXL (36 eyes; ACXL group), and Trans-ACXL (33 eyes; Trans-ACXL group). Patients were evaluated through visual acuity, keratometry, corneal biomechanics, corneal tomography, endothelial cell count, anterior segment optical coherence tomography and in vivo confocal microscopy. The follow-up period was 12 months.
Results : Transient haze was observed in 21% of keratoconic corneas in the ACXL group and none in the Trans-ACXL group. There were no significant postoperative differences in astigmatism, corneal biomechanical parameters or endothelial cell counts; while visual acuity, keratometry and manifest refraction spherical equivalent showed significant improvement at 12th months postoperatively in both groups. The demarcation line depth was 220.27±41.34 µm in ACXL group, deeper than in Trans-ACXL group, whose depth was 197.54±32.37 µm (P = 0.014), at 1 month postoperation. In vivo confocal microscopy showed keratocytes apoptosis and stromal edema 1 month postoperation; but the changes gradually recovered similar to normal status after 12 month postoperation in both groups. There were no apparent changes to the posterior stroma and endothelium in either group.
Conclusion : The results of this study revealed that both ACXL and Trans-ACXL were safe and effective at stabilizing the progression of keratoconus. The ACXL technique offers more effective visual and topographic outcomes than Trans-ACXL, but Trans-ACXL with less micro-structural damage.
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