title: Age-related differences in the elasticity of the human cornea.
abstract: OBJECTIVE
  The goal of this study was to determine age-related variation in the elasticity of the human cornea using nondestructive means.
  
  
  METHODS
  Organ cultured human corneoscleral buttons were studied. Changes in strain were measured with a radial shearing speckle pattern interferometer after an increase in intraocular pressure from 15.0 to 15.5 mm Hg. Changes in central corneal displacement were calculated by integration, and a bulk corneal Young's modulus was derived by mathematical analysis.
  
  
  RESULTS
  Fifty corneas, including 17 pairs, were studied. Donors were aged between 24 and 102 years (mean, 73.1); 29 (58%) specimens were from male donors and 21 from female donors. Young's modulus of the cornea increased with age, with the line of best fit indicating an approximate doubling from 0.27 MPa at age 20 years (95% confidence interval, 0.22-0.31) to 0.52 (0.50-0.54) MPa at age 100 years (R² = 0.70).
  
  
  CONCLUSIONS
  The stiffness of the human cornea increases by a factor of approximately two between the ages of 20 and 100 years. This variation is relevant to the algorithms used to predict the response to incisional and ablative refractive surgery and will also affect the formulas used to calculate intraocular pressure by applanation.
authors.affiliation: Department of Ophthalmology, King's College London, London, UK. n.knoxcartwright@gmail.com
authors.forename: Nathaniel E
authors.initials: NE
authors.lastname: Knox Cartwright
authors.forename: John R
authors.initials: JR
authors.lastname: Tyrer
authors.forename: John
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000502:physiology*; D055119:Elastic Modulus; D004548:Elasticity; D005260:Female; D006801:Humans; D007368:Interferometry; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D055815:Young Adult