Influence of Age on Ocular Biomechanical Properties in a Canine Glaucoma Model with ADAMTS10 Mutation.
Soft tissue often displays marked age-associated stiffening. This study aims to investigate how age affects scleral biomechanical properties in a canine glaucoma model with ADAMTS10 mutation, whose extracellular matrix is concomitantly influenced by the mutation and an increased mechanical load from an early age. Biomechanical data was acquired from ADAMTS10-mutant dogs (n = 10, 21 to 131 months) and normal dogs (n = 5, 69 to 113 months). Infusion testing was first performed in the whole globes to measure ocular rigidity. After infusion experiments, the corneas were immediately trephined to prepare scleral shells that were mounted on a pressurization chamber to measure strains in the posterior sclera using an inflation testing protocol. Dynamic viscoelastic mechanical testing was then performed on dissected posterior scleral strips and the data were combined with those reported earlier by our group from the same animal model (Palko et al, IOVS 2013). The association between age and scleral biomechanical properties was evaluated using multivariate linear regression. The relationships between scleral properties and the mean and last measured intraocular pressure (IOP) were also evaluated. Our results showed that age was positively associated with complex modulus (p<0.001) and negatively associated with loss tangent (p<0.001) in both the affected and the normal groups, suggesting an increased stiffness and decreased mechanical damping with age. The regression slopes were not different between the groups, although the complex modulus was significantly lower in the affected group (p = 0.041). The posterior circumferential tangential strain was negatively correlated with complex modulus (R = -0.744, p = 0.006) showing consistent mechanical evaluation between the testing methods. Normalized ocular rigidity was negatively correlated with the last IOP in the affected group (p = 0.003). Despite a mutation that affects the extracellular matrix and a chronic IOP elevation in the affected dogs, age-associated scleral stiffening and loss of mechanical damping were still prominent and had a similar rate of change as in the normal dogs.
Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, United States of America.|Department of Ophthalmology, Washington University, St. Louis, Missouri, United States of America.
Joel R
JR
Palko
Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, United States of America.
Hugh J
HJ
Morris
Center for Biostatistics, Ohio State University, Columbus, OH, United States of America.
Xueliang
X
Pan
Department of Small Animal Clinical Sciences, Michigan State University, Lansing, Michigan, United States of America.
Christine D
CD
Harman
Department of Small Animal Clinical Sciences, Michigan State University, Lansing, Michigan, United States of America.
Kristin L
KL
Koehl
Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America.
Kirk N
KN
Gelatt
Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America.
Caryn E
CE
Plummer
Department of Small Animal Clinical Sciences, Michigan State University, Lansing, Michigan, United States of America.|Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America.|Department of Clinical Studies, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
András M
AM
Komáromy
Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, United States of America.|Department of Ophthalmology, Ohio State University, Columbus, Ohio, United States of America.
Jun
J
Liu
D000071096:ADAMTS Proteins / Q000235:genetics*; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena / Q000235:genetics; D004195:Disease Models, Animal; D004285:Dogs; D004548:Elasticity; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005260:Female; D005901:Glaucoma / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D007429:Intraocular Pressure / Q000235:genetics; D008297:Male; D020125:Mutation, Missense; D012590:Sclera / Q000503:physiopathology*; D014065:Tonometry, Ocular
D000071096:ADAMTS Proteins