title: Morphological and functional correlations in riboflavin UV A corneal collagen cross-linking for keratoconus.
abstract: OBJECTIVE
  To investigate the correlations between corneal structural modifications assessed by in vivo corneal confocal microscopy with visual function [uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA)] and morphological data (corneal topography, pachymetry, elevation analysis) after riboflavin UV A corneal collagen cross-linking (CXL) for the stabilization of progressive keratoconus.
  
  
  METHODS
  Forty-four eyes with progressive keratoconus were enrolled in the Siena Eye Cross Study (prospective nonrandomized phase II open trial). All eyes underwent Riboflavin UV A CXL. Preoperative and postoperative evaluation comprised: UCVA, BSCVA, optical pachymetry (Visante OCT, Zeiss, Germany), corneal topography (CSO, Florence, Italy) and tomography (Orbscan IIz; B&L, Rochester, NY, USA) and in vivo confocal microscopy (Heidelberg Retina Tomograph II; Rostock, Heidelberg Gmbh, Germany). Examinations were performed preoperatively 6 months and one day before treatment and at 1, 3, 6 and 12 months of follow-up.
  
  
  RESULTS
  In vivo corneal confocal microscopy showed time-dependent postoperative epithelial and stromal modifications after cross-linking. Epithelial thinning associated with stromal oedema and keratocytes apoptosis explained initial tendency towards slightly reduced VA and more glare one month postoperatively in 70% of eyes. Furthermore, a statistically not significant early worsening of topographic mean K values was observed. Orbscan II analysis significantly underestimated pachymetric values after treatment. Pachymetric underestimation was rectified by high-resolution optical pachymetry provided by the Visante OCT system. After the third post-CXL month, epithelial thickening, disappearance of oedema and new collagen compaction recorded by in vivo corneal confocal microscopy explained the improvements in visual performance during the follow-up. Changes in stromal reflectivity and collagen compaction observed by in vivo confocal microscopy were associated with corneal flattening and reduction in anterior elevation values recorded by differential topographic analysis.
  
  
  CONCLUSIONS
  Corneal structural changes assessed by in vivo corneal confocal microscopy demonstrated significant correlations with visual function (UCVA and BSCVA) and morphological (corneal topography, pachymetry, elevation analysis) findings recorded after riboflavin-UV A-induced CXL.
authors.affiliation: Department of Ophthalmology, Siena University, Siena, Italy. cgmazzotta@libero.it
authors.forename: Cosimo
authors.initials: C
authors.lastname: Mazzotta
authors.forename: Tomaso
authors.initials: T
authors.lastname: Caporossi
authors.forename: Rosario
authors.initials: R
authors.lastname: Denaro
authors.forename: Cristina
authors.initials: C
authors.lastname: Bovone
authors.forename: Caterina
authors.initials: C
authors.lastname: Sparano
authors.forename: Anna
authors.initials: A
authors.lastname: Paradiso
authors.forename: Stefano
authors.initials: S
authors.lastname: Baiocchi
authors.forename: Aldo
authors.initials: A
authors.lastname: Caporossi
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism / Q000473:pathology*; D003319:Corneal Stroma / Q000378:metabolism; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D018613:Microscopy, Confocal; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin