title: Changes in Forward and Backward Light Scatter in Keratoconus Resulting From Corneal Cross-Linking.
abstract: OBJECTIVE
  To study the forward and backward light scatter in keratoconic corneas before and after cross-linking.
  
  
  METHODS
  An institutional, prospective, cross-sectional study was conducted.
  
  
  METHODS
  This study includes 35 eyes of 25 patients with keratoconus scheduled for either standard corneal collagen cross-linking with riboflavin (CXL) or transepithelial corneal cross-linking (TE-CXL). A group of 26 healthy myopic eyes from 26 prerefractive patients was included as normal reference. Before and 6 months after cross-linking, forward light scatter was measured using the compensation comparison method, whereas backward light scatter was measured using Scheimpflug imaging.
  
  
  RESULTS
  In keratoconic eyes, backward light scatter originating from the corneal stroma was [mean (SD)] 27.2% (8.2%) higher than in the normal eyes (P < 0.001). In the anterior stroma, this increased backscatter was significantly correlated with the maximum corneal curvature Kmax as a measure of keratoconus severity (Pearson ρ = 0.582, P = 0.003). For forward light scatter, no significant difference was seen between the normal and keratoconus groups, nor was there any correlation with keratoconus severity. After CXL, the backscatter increased significantly by [mean (SD)] 33.0% (9.5%) in the entire corneal stroma (P = 0.001), whereas for TE-CXL, no significant increase was seen. Forward scatter increased significantly by [mean (SD)] 0.10 (0.10) log units (P = 0.009) and 0.09 (0.10) log units (P = 0.003) for CXL and TE-CXL, respectively, which is near the detection limit for an average patient.
  
  
  CONCLUSIONS
  Unlike TE-CXL, CXL increases the already-elevated stromal backscatter in keratoconus. Forward scatter increases equally for both techniques.
authors.affiliation: From the *Department of Ophthalmology, Antwerp University Hospital, Edegem; and †Department of Medicine, Antwerp University, Wilrijk, Belgium.
authors.forename: Jos J
authors.initials: JJ
authors.lastname: Rozema
authors.forename: Carina
authors.initials: C
authors.lastname: Koppen
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bral
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Tassignon