title: Intraoperative corneal thickness measurement by optical coherence tomography in keratoconic patients undergoing corneal collagen cross-linking.
abstract: OBJECTIVE
  To assess intraoperative variation of corneal thinnest point in keratoconic patients undergoing riboflavin/ultraviolet type A (UV-A) cross-linking treatment using noncontact time-domain optical pachymetry.
  
  
  METHODS
  Prospective, noncomparative interventional study.
  
  
  METHODS
  Ten patients underwent epithelium-off riboflavin/UV-A corneal cross-linking at Siena University Hospital; corneal thickness was measured using optical coherence tomography at the following times: preoperatively with epithelium on; after removal of a 9-mm-diameter disc of epithelium; immediately after instillation of 2 drops of riboflavin 0.1%-dextran T 500 20% solution; after repeated instillation of riboflavin 0.1%-dextran T 500 20% solution every 2.5 minutes, at 10, 20, and 30 minutes of soaking time; at the end of the treatment after 30 minutes of UV-A exposure with the riboflavin biofilm in situ; and finally after washing the riboflavin biofilm.
  
  
  RESULTS
  The most significant decrease in thinnest point measurement was detected meanly in the first 10 minutes of corneal soaking. In this interval, the minimum recommended in various studies, a mean reduction of -79.28 μm (-17.61% of initial thinnest point value after removal of the epithelium) was recorded. No adverse events were recorded.
  
  
  CONCLUSIONS
  The study demonstrates a statistically significant intraoperative reduction in corneal thinnest point value during epithelium-off cross-linking procedure using standard riboflavin 0.1%-dextran 20% solutions. Intraoperative optical pachymetry evaluation during cross-linking should be recommended before starting UV-A irradiation, and if a thickness under 380 μm is detected, the stroma should be reexpanded with hypotonic dextran-free riboflavin solutions.
authors.affiliation: Department of Ophthalmology, Siena University, Siena, Italy. Electronic address: cgmazzotta@libero.it.
authors.forename: Cosimo
authors.initials: C
authors.lastname: Mazzotta
authors.affiliation: Department of Ophthalmology, Siena University, Siena, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Caragiuli
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D009929:Organ Size; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D041623:Tomography, Optical Coherence / Q000379:methods*; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin