title: A histological study of rabbit corneas after transepithelial corneal crosslinking using partial epithelial photoablation or ethanol treatment.
abstract: OBJECTIVE
  To evaluate the histological changes after transepithelial corneal crosslinking (CXL) using partial thickness excimer laser ablation or epithelial ethanol application in an experimental rabbit study.
  
  
  METHODS
  Right eyes of twenty-four rabbits were studied. Four eyes received total epithelial debridement (group I). Four eyes received partial thickness epithelial ablation with excimer laser (group II). Twelve eyes were treated with different durations (30s and 60s) and concentrations (18% to 48%) of ethanol (group III). Riboflavin was applied for 30min intervals along with topical proparacaine drops with benzalkonium chloride, and 370 nm irradiation was performed for 30min, while riboflavin was instilled every 3min. Four eyes (group IV) received 48% ethanol for 30s without riboflavin and irradiation. Eyes were collected after 24h and examined histologically.
  
  
  RESULTS
  All eyes in group I showed keratocyte loss in the superficial 300 µ of corneal storma. In group II, 1-4 layers of epithelium were preserved and no keratocyte loss occurred. In group III, CXL after treatment with ethanol up to 24% concentration and up to 60s revealed no keratocyte loss. CXL after treatment with 48% and higher ethanol concentrations yielded keratocyte loss in the superficial 200 µ to 300 µ of cornea.
  
  
  CONCLUSIONS
  Incomplete excimer laser ablation of the epithelium or treatment with ethanol up to 24% concentration and up to 60s duration yielded no stromal keratocyte loss. To get the same histological appearance seen in epithelial debridement group, partial thickness excimer laser epithelial ablation or ethanol application is not adequate for transepithelial CXL.
authors.affiliation: Department of Ophthalmology, Gazi University, Ankara 06500, Turkey.
authors.forename: Mehmet Cuneyt
authors.initials: MC
authors.lastname: Ozmen
authors.affiliation: Department of Ophthalmology, Gazi University, Ankara 06500, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Hondur
authors.affiliation: Department of Pathology, Gazi University, Ankara 06500, Turkey.
authors.forename: Guldal
authors.initials: G
authors.lastname: Yilmaz
authors.affiliation: Department of Ophthalmology, Gazi University, Ankara 06500, Turkey.
authors.forename: Kamil
authors.initials: K
authors.lastname: Bilgihan
authors.affiliation: Department of Ophthalmology, Gazi University, Ankara 06500, Turkey.
authors.forename: Berati
authors.initials: B
authors.lastname: Hasanreisoglu
keywords: crosslinking; ethanol; histology; keratoconus; photoablation; transepithelial