title: Pulsed vs continuous light accelerated corneal collagen crosslinking: in vivo qualitative investigation by confocal microscopy and corneal OCT.
abstract: OBJECTIVE
  To assess qualitative corneal changes and penetration of pulsed and continuous light accelerated crosslinking by in vivo confocal microscopy and corneal OCT.
  
  
  METHODS
  A total of 20 patients affected from progressive keratoconus were enrolled in the study. Ten eyes of 10 patients underwent an epithelium-off pulsed-light accelerated corneal collagen crosslinking (PL-ACXL) by the KXL UV-A source (Avedro Inc.) with 8 min (1 s on/1 s off) of UV-A exposure at 30 mW/cm(2) and energy dose of 7.2 J/cm(2); 10 eyes of 10 patients underwent an epithelium-off continuous-light accelerated corneal collagen crosslinking (CL-ACXL) at 30 mW/cm(2) for 4 min. Riboflavin 0.1% dextran-free plus hydroxyl-propyl-methylcellulose solution (VibeX Rapid, Avedro Inc.) was used for a 10-min corneal soaking. Treated eyes were examined by in vivo scanning laser confocal analysis and spectral anterior segment OCT at 1, 3, and 6 months.
  
  
  RESULTS
  Epithelial stratification and nerves regeneration improved in time, being complete at month 6 in both groups without endothelial damage. Keratocyte apoptosis in PL-ACXL was estimated at a mean depth of ∼200 μm, whereas an uneven demarcation line was detectable by confocal microscopy at a mean depth of 160 μm in CL-ACXL.
  
  
  CONCLUSIONS
  In vivo confocal microscopy and corneal OCT allowed a precise qualitative analysis of the cornea after epithelium-off PL-ACXL and CL-ACXL treatments. Apoptotic effect was higher in pulsed than in continuous light treatments, exceeding 200 μm in corneal stroma. According to different morphological data, the clinical efficacy of ACXL needs to be determined in a long-term follow-up and large cohort of patients.
authors: Department of Medical, Surgical and Neurosciences, Ophthalmology Unit, Siena University, Siena, Italy.
authors: C
authors: C
authors: Mazzotta
authors: Department of Medical, Surgical and Neurosciences, Ophthalmology Unit, Siena University, Siena, Italy.
authors: C
authors: C
authors: Traversi
authors: Department of Medical, Surgical and Neurosciences, Ophthalmology Unit, Siena University, Siena, Italy.
authors: S
authors: S
authors: Caragiuli
authors: Department of Ophthalmology, Catanzaro 'Magna Grecia' University, Catanzaro, Italy.
authors: M
authors: M
authors: Rechichi
mesh_terms: D000293:Adolescent; D000328:Adult; D002452:Cell Count; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000294:innervation; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004728:Endothelium, Corneal / Q000473:pathology; D019573:Epithelium, Corneal / Q000502:physiology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D009416:Nerve Regeneration / Q000502:physiology; D009882:Ophthalmic Nerve / Q000502:physiology; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use*; D041623:Tomography, Optical Coherence; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin