title: Characterization of age-related variation in corneal biomechanical properties.
abstract: An experimental study has been conducted to determine the stress-strain behaviour of human corneal tissue and how the behaviour varies with age. Fifty-seven well-preserved ex vivo donor corneas aged between 30 and 99 years were subjected to cycles of posterior pressure up to 60 mm Hg while monitoring their behaviour. The corneas were mechanically clamped along their ring of scleral tissue and kept in physiological conditions of temperature and hydration. The tissue demonstrated hyper-elastic pressure-deformation and stress-strain behaviour that closely matched an exponential trend. Clear stiffening (increased resistance to deformation) with age was observed in all loading cycles, and the rate of stiffness growth was nonlinear with bias towards older specimens. With a strong statistical association between stiffness and age (p < 0.05), it was possible to develop generic stress-strain equations that were suitable for all ages between 30 and 99 years. These equations, which closely matched the experimental results, depicted corneal stiffening with age in a form suitable for implementation in numerical simulations of ocular biomechanical behaviour.
authors.affiliation: Division of Civil Engineering, University of Dundee, Dundee DD1 4HN, UK. a.i.h.elsheikh@dundee.ac.uk
authors.forename: Ahmed
authors.initials: A
authors.lastname: Elsheikh
authors.forename: Brendan
authors.initials: B
authors.lastname: Geraghty
authors.forename: Paolo
authors.initials: P
authors.lastname: Rama
authors.forename: Marino
authors.initials: M
authors.lastname: Campanelli
authors.forename: Keith M
authors.initials: KM
authors.lastname: Meek
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D003315:Cornea / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D013314:Stress, Mechanical
references.citation: Br J Ophthalmol. 2005 Dec;89(12):1572-5
references.pmid: 16299132
references.citation: Surv Ophthalmol. 1994 May;38 Suppl:S191-7
references.pmid: 7940143
references.citation: J Biomech Eng. 2008 Apr;130(2):021011
references.pmid: 18412498
references.citation: Invest Ophthalmol Vis Sci. 2008 Oct;49(10):4232-6
references.pmid: 18539943
references.citation: Br J Ophthalmol. 1999 Oct;83(10):1106-11
references.pmid: 10502567
references.citation: Biochim Biophys Acta. 1992 Mar 20;1138(3):222-8
references.pmid: 1547284
references.citation: Cont Lens Anterior Eye. 2001;24(1):41-6
references.pmid: 16303452
references.citation: Nature. 1979 Nov 8;282(5735):213-5
references.pmid: 492338
references.citation: Clin Exp Optom. 2006 May;89(3):124-43
references.pmid: 16637967
references.citation: Exp Eye Res. 2004 Mar;78(3):503-12
references.pmid: 15106929
references.citation: Invest Ophthalmol Vis Sci. 1998 Mar;39(3):644-8
references.pmid: 9501878
references.citation: Invest Ophthalmol Vis Sci. 1992 Jun;33(7):2224-8
references.pmid: 1607232
references.citation: Curr Eye Res. 2007 Jan;32(1):11-9
references.pmid: 17364730
references.citation: Atherosclerosis. 1996 Dec 20;127(2):155-65
references.pmid: 9125305
references.citation: Metab Pediatr Syst Ophthalmol. 1983;7(4):183-8
references.pmid: 6678372
references.citation: Ophthalmic Physiol Opt. 1997 Jan;17(1):68-74
references.pmid: 9135815
references.citation: Bull Math Biol. 1999 May;61(3):551-72
references.pmid: 17883231
references.citation: Eye Contact Lens. 2007 Nov;33(6 Pt 1):265-71
references.pmid: 17993819
references.citation: Ophthalmology. 2004 Dec;111(12):2211-9
references.pmid: 15582076
references.citation: Biophys J. 1993 Jan;64(1):273-80
references.pmid: 8431547
references.citation: Exp Eye Res. 2008 May;86(5):783-90
references.pmid: 18396276
references.citation: Arch Ophthalmol. 1997 Aug;115(8):1051-7
references.pmid: 9258228
references.citation: J Struct Biol. 2005 Jan;149(1):1-6
references.pmid: 15629652
references.citation: J R Soc Interface. 2004 Nov 22;1(1):3-15
references.pmid: 16849148
references.citation: Vision Res. 2006 Mar;46(6-7):993-1001
references.pmid: 16266736
references.citation: Invest Ophthalmol Vis Sci. 1991 Jul;32(8):2244-58
references.pmid: 2071337
references.citation: Atherosclerosis. 1998 Sep;140(1):135-45
references.pmid: 9733224
references.citation: J Glaucoma. 2008 Jun-Jul;17(4):318-28
references.pmid: 18552618
references.citation: J Struct Biol. 2009 May;166(2):195-204
references.pmid: 19258040
references.citation: Br J Ophthalmol. 2005 Jul;89(7):851-4
references.pmid: 15965165
references.citation: Cornea. 1998 Sep;17(5):537-43
references.pmid: 9756449
references.citation: J Cataract Refract Surg. 2005 Jan;31(1):146-55
references.pmid: 15721707
references.citation: Exp Eye Res. 2004 Sep;79(3):343-50
references.pmid: 15336496
references.citation: J Biomech. 2001 Apr;34(4):533-7
references.pmid: 11266678
references.citation: Invest Ophthalmol Vis Sci. 2009 Nov;50(11):5226-37
references.pmid: 19494203
references.citation: Br J Ophthalmol. 2010 Apr;94(4):519-22
references.pmid: 19833614
references.citation: J Biomech Eng. 2006 Feb;128(1):150-60
references.pmid: 16532629
references.citation: Biochem J. 1998 Feb 15;330 ( Pt 1):345-51
references.pmid: 9461529
references.citation: Ann Biomed Eng. 2000 Sep;28(9):1093-100
references.pmid: 11132193
references.citation: Invest Ophthalmol Vis Sci. 1997 Feb;38(2):357-63
references.pmid: 9040468
references.citation: Curr Eye Res. 2008 Mar;33(3):205-13
references.pmid: 18350431
references.citation: Cont Lens Anterior Eye. 2008 Apr;31(2):95-102
references.pmid: 18356094
references.citation: Ann Biomed Eng. 2006 Jan;34(1):169-83
references.pmid: 16474919
references.citation: Br J Ophthalmol. 2000 Mar;84(3):318-23
references.pmid: 10684845
references.citation: Biochem Biophys Res Commun. 1996 Feb 15;219(2):311-5
references.pmid: 8604983
references.citation: Exp Eye Res. 2004 Mar;78(3):493-501
references.pmid: 15106928
references.citation: Exp Eye Res. 2008 Feb;86(2):445-51
references.pmid: 18221938
references.citation: Ann Ophthalmol. 1973 Mar;5(3):285-7 passim
references.pmid: 4694913
references.citation: J Refract Surg. 2007 Oct;23(8):808-18
references.pmid: 17985801
references.citation: Clin Exp Ophthalmol. 2002 Jun;30(3):173-5
references.pmid: 12010208
references.citation: Biomaterials. 2008 Oct;29(28):3896-904
references.pmid: 18603294
references.citation: J Biomech Eng. 1996 Nov;118(4):473-81
references.pmid: 8950650