Evaluation of corneal demarcation line and associated parameters in patients with keratoconus following transepithelial, epithelial scoring and epithelium-off accelerated corneal collagen crosslinking

Introduction: Keratoconus is a progressive corneal ectatic disorder with thinning, protrusion and poor vision. Corneal collagen crosslinking (CXL) is a minimally invasive procedure used to prevent progression. CXL is performed either after epithelial debridement (Epi-Off) or with the epithelium in-situ (transepithelially).
Objective: To evaluate corneal demarcation line and associated parameters in patients with keratoconus following accelerated CXL using the described methods. Materials and methods: Retrospective data of twelve consecutive eyes (n=12) which underwent CXL using the method described by the authors was compared with randomized data of sixteen eyes (n=11) which underwent transepithelial CXL and eighteen eyes (n=14) which underwent Epi-Off CXL. An accelerated CXL protocol was used (UVA 9mW/cm² for 10 min) in all patients after instillation of 0.1% riboflavin solution for 30 minutes. The surgeon made linear full thickness epithelial abrasions in the modified technique. Visual acuity, keratometry, pachymetry were evaluated preoperatively and at one month postop. Specular microscopy and AS-OCT was performed at one month postop.
Results: Preoperative Kmax, Kmean and cylinder power were similar in all groups. However, patients who underwent the modified technique had poorer UCDVA and BCDVA at baseline (MRSEQ-4.41) and average pachymetry of 450 μm. Postoperatively, patients who underwent the modified technique had mild stromal haze, a well visible stromal demarcation line on AS-OCT and a higher average endothelial cell count on specular microscopy. Keratometry and pachymetry values were stable in all groups.
Conclusion: Preliminary data indicate that the method described by the authors can be used in thinner corneas to improve efficacy of CXL compared to the transepithelial approach.