Contact Lens-Assisted Collagen Cross-Linking (CACXL): A New Technique for Cross-Linking Thin Corneas

PURPOSE: To report a novel method of contact lens-assisted corneal cross-linking (CACXL) in eyes with thin corneas. METHODS: Patients diagnosed as having progressive keratectasia with a minimum corneal thickness less than 400 and greater than 350 μm after epithelial abrasion were included. After epithelial abrasion, the iso-osmolar riboflavin 0.1% in dextran was applied every 3 minutes for 30 minutes. An ultraviolet barrier-free soft contact lens (0.09-mm thickness, 14-mm diameter) soaked in iso-osmolar riboflavin 0.1% for 30 minutes was placed on the cornea. Once the minimum corneal thickness value was confirmed to be greater than 400 μm, the ultraviolet-A irradiance was started along with instillation of iso-osmolar riboflavin 0.1% in the pre-corneal and pre-contact lens region. Intraoperative minimum corneal thickness changes were recorded with ultrasound pachymetry and optical coherence tomography. Postoperative visual acuity, corneal topography (Orbscan; Bausch & Lomb, Rochester, NY), endothelial cell loss (EM-3000; Tomey, Nagoya, Japan), and stromal demarcation line (Visante; Carl Zeiss Meditec, Jena, Germany) were measured. RESULTS: Fourteen eyes underwent the procedure. Mean preoperative minimum corneal thickness after epithelial abrasion was 377.2 ± 14.5 μm (range: 350 to 398 μm). There was a significant difference in minimum functional corneal thickness (Friedman test, P = .000) intraoperatively, before epithelial abrasion, after epithelial abrasion, and with contact lens and riboflavin film. Mean minimum functional corneal thickness after the contact lens was 485.1 ± 15.8 μm (range: 458 to 511 μm). Mean absolute increase in the minimum corneal thickness along with the contact lens and pre-corneal riboflavin film was 107.9 ± 9.4 μm (range: 90 to 124 μm). Mean depth of stromal demarcation line was 252.9 ± 40.8 μm (range: 208 to 360 μm). There was no significant endothelial loss (P = .063) and the corneal topography was stable at the last follow-up (P = .505). CONCLUSIONS: CACXL technique was effective and safe in performing cross-linking in corneas less than 400 μm after epithelial abrasion and appeared effective based on stromal demarcation line depth.