title: In Vivo Confocal Microscopy After Contact Lens-Assisted Corneal Collagen Cross-linking for Thin Keratoconic Corneas.
abstract: OBJECTIVE
  To study in vivo confocal microscopy (IVCM) after contact lens-assisted corneal collagen cross-linking (CACXL) in keratoconic eyes with thin corneas.
  
  
  METHODS
  This prospective interventional case series included patients with progressive keratoconus with minimum corneal thickness less than 400 µm after removing epithelium. CACXL was done once functional corneal thickness was confirmed to be 400 µm or greater after applying a riboflavin-soaked, ultraviolet barrier-free contact lens. Postoperative IVCM at 1, 3, and 6 months was performed.
  
  
  RESULTS
  Ten eyes underwent CACXL. Mean preoperative minimum corneal thickness after epithelial removal was 376 µm (range: 364 to 397 µm). IVCM at 1 month showed CACXL-induced apoptosis evenly distributed at 350 ± 30 µm measured from epithelial surface. The demarcation line between edematous stroma and deep stroma beyond 350 µm that appeared unaltered was appreciable at 1 and 3 months but not at 6 months. Corneal reinnervation was visible at 3 months and was fully restored by 6 months. Regular endothelial mosaic was seen at all times. At 6 months, keratocyte repopulation of anterior stroma, disappearance of edema, and deposition of denser extracellular matrix surrounding activated keratocytes was seen with hyperreflective microbands still detectable. Average endothelial count was 2,135 ± 56 cells/mm(2) preoperatively versus 2,190 ± 41 cells/mm(2) at 6 months postoperatively.
  
  
  CONCLUSIONS
  CACXL increases functional corneal thickness during ultraviolet light application, thus over-coming conventional pachymetric limitations of CXL. Cytotoxic effects of CACXL are similar to IVCM changes seen in conventional CXL and were concentrated in anterior and intermediate stroma up to 300 ± 30 µm without epithelium. Anterior segment optical coherence tomography should be performed after contact lens application and before ultraviolet light treatment to confirm an increase in functional thickness greater than 400 µm. For thinner corneas, combination treatments should be evaluated. [J Refract Surg. 2016;32(5):326-331.].
authors.forename: Cosimo
authors.initials: C
authors.lastname: Mazzotta
authors.forename: Soosan
authors.initials: S
authors.lastname: Jacob
authors.forename: Amar
authors.initials: A
authors.lastname: Agarwal
authors.forename: Dhivya Ashok
authors.initials: DA
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003261:Contact Lenses; D060527:Corneal Keratocytes / Q000473:pathology; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology*; D003432:Cross-Linking Reagents; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D041623:Tomography, Optical Coherence; D014466:Ultraviolet Rays; D014792:Visual Acuity; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin