title: Efficacy of Blue-Light Cross-linking on Human Scleral Reinforcement.
abstract: OBJECTIVE
  To evaluate the biomechanical effects of collagen cross-linking by riboflavin/blue light (460 nm) on human sclera.
  
  
  METHODS
  Forty-two sclera samples from donated human eyes were treated with riboflavin at 0.5% on the equatorial sclera for 20 minutes and then randomly divided into seven groups and irradiated, respectively, with blue light at different intensities (14.6, 19.5, 22.5, 26, 32.5, and 40.6 mW/cm) for 20 minutes using a light-emitting diode source with an exposure area of 10 mm in diameter. The untreated samples constituted the control group. During irradiation, continuous riboflavin solution infiltration was carried out for 20 minutes. Stress-strain measurements of scleral strips were performed with a biomaterial tester. Stress data and Young modulus values in different groups were compared by one-way analysis of variance.
  
  
  RESULTS
  Blue-light (460 nm) cross-linking was efficient in stiffening human sclera strips. Interestingly, eyes treated with 22.5 mW/cm exhibited higher Young modulus values (19.12 [±4.88] MPa) at 8% strain compared with other groups, representing a 307.68% increase over control eye values (4.69 [±1.26] MPa). Stress and Young modulus increased gradually with irradiation intensity from 19.5 to 22.5 mW/cm before decreasing for higher intensities.
  
  
  CONCLUSIONS
  The biomechanical strength of human sclera may be enhanced by collagen cross-linking with riboflavin/460 nm blue-light irradiation; the dose of 22.5 mW/cm might be used for blue-light (460 nm) scleral cross-linking to achieve a higher efficacy.
authors.affiliation: *MD †MD, PhD Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Lab, Beijing, China (all authors).
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zou
authors.forename: Fengju
authors.initials: F
authors.lastname: Zhang
authors.forename: Xuemin
authors.initials: X
authors.lastname: Zhang
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Wang
mesh_terms: D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents; D055119:Elastic Modulus; D004547:Elastic Tissue; D006801:Humans; D008027:Light; D008875:Middle Aged; D017319:Photosensitizing Agents / Q000494:pharmacology*; D012256:Riboflavin / Q000494:pharmacology*; D012590:Sclera / Q000187:drug effects* / Q000378:metabolism; D014019:Tissue Donors
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin