title: Correlation of discoloration and biomechanical properties in porcine sclera induced by genipin.
abstract: OBJECTIVE
  To study the feasibility of using the discoloration to evaluate the biomechanical properties after treating with genipin.
  
  
  METHODS
  Porcine cadaver eyes were treated for 30min with 1.0% (by w/v) genipin. Untreated samples were used as controls. After treatment, scleral strips of 4.0×10.0-mm(2) were cut. The denaturation temperature (Td) measurement and stress-strain test were performed after taking photograph to analyze the color.
  
  
  RESULTS
  Within 24h after treating with genipin, the sclera exhibited a bluish color which became deeper with time. And the denaturation temperature also was increased gradually. Compared with untreated groups, at 1, 6, 12, 24 and 36h after treatment, the ultimate stress were increased by 56%, 153%, 173%, 225% and 211% respectively. The Young's modulus at 10% strain also increased by 170%, 246%, 264%, 389% and 288% respectively. There were strong correlation between the discoloration and the biomechanical properties (ΔE-Ultimate stress: R(2)=0.892, P=0.00; ΔE-Young's modulus: R(2)=0.602, P=0.00).
  
  
  CONCLUSIONS
  Genipin could be used to strengthen collagen gradually in a relatively short time span. And the biomechanical properties could be reliably evaluated via simple visible discoloration.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China ; Department of Ophthalmology, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, Guizhou Province, China.
authors.forename: Tai-Xiang
authors.initials: TX
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, Guizhou Province, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
keywords: biomechanics; crosslinking; discoloration; genipin; sclera