Corneal confocal microscopy following conventional, transepithelial, and accelerated corneal collagen cross-linking procedures for keratoconus.
OBJECTIVE
To compare early corneal healing following conventional, transepithelial, and accelerated corneal collagen cross-linking (CXL) protocols.


METHODS
Twenty-four patients with progressive keratoconus were divided into three groups to receive conventional, transepithelial, or accelerated CXL. In vivo corneal confocal microscopy was performed on each patient preoperatively and at 1, 3, and 6 months postoperatively.


RESULTS
Closure of the epithelial wound was complete 3 days following conventional and accelerated CXL. The subbasal nerve plexus was essentially obliterated immediately following conventional and accelerated CXL, and virtually no nerve fibers had regenerated by 6 months. The anterior stroma showed significant changes 1 month following conventional CXL; these changes were similar but more pronounced following accelerated CXL. Observed stromal changes included complete obliteration of keratocytes, increased tissue reflectivity, a honeycomb-like appearance, and circular lacunae. Some recovery of keratocyte density was noted after 6 months. These changes were less pronounced in the mid-stroma, and there were no apparent changes to the posterior stroma or endothelium. The cornea appeared to be unaltered following transepithelial CXL.


CONCLUSIONS
In vivo corneal confocal microscopy analysis of the postoperative impact of CXL on the cornea revealed clear differences among conventional, accelerated, and transepithelial CXL protocols. Accelerated CXL had a greater impact than conventional CXL on the anterior cornea, whereas transepithelial CXL did not appear to alter corneal morphology.
French National Reference Center for Keratoconus, Centre Hospitalier Universitaire de Bordeaux, Service d'Ophtalmologie, Site Pellegrin, Centre François Xavier Michelet, Bordeaux Cedex, France. toubould@gmail.com
David
D
Touboul
Nathan
N
Efron
David
D
Smadja
Delphine
D
Praud
Florence
F
Malet
Joseph
J
Colin
D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000294:innervation; D003319:Corneal Stroma / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D019573:Epithelium, Corneal / Q000378:metabolism; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D018613:Microscopy, Confocal; D009415:Nerve Net / Q000187:drug effects / Q000473:pathology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D014276:Trigeminal Nerve / Q000187:drug effects / Q000473:pathology; D014466:Ultraviolet Rays; D014945:Wound Healing / Q000502:physiology
D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin