Abstract
BackgroundCornea is a composite tissue exhibiting nonlinear and time-dependent mechanical properties. Corneal ulcers are one of the main pathologies that affect this tissue, disrupting its structural integrity and leading to impaired functions. In this study, uniaxial tensile and stress-relaxation tests are developed to evaluate stress-strain and time-dependent mechanical behaviour of porcine corneas.ResultsThe samples are split in two groups: some corneas are analysed in an unaltered state (healthy samples), while others are injured with alkaline solution to create an experimental ulcer (lesioned samples). Furthermore, within each group, corneas are examined in two conditions: few hours after the enucleation (fresh samples) or after 7 days in a specific culture medium for the tissue (cultured samples). Finally, another condition is added: corneas from all the groups undergo or not a cross-linking treatment. In both stress-strain and stress-relaxation tests, a weakening of the tissue is observed due to the imposed conditions (lesion, culture and treatment), represented by a lower stiffness and increased stress-relaxation.ConclusionsAlkali-induced corneal stromal melting determines changes in the mechanical response that can be related to a damage at microstructural level. The results of the present study represent the basis for the investigation of traditional and innovative corneal therapies.
Highlights
Cornea is a composite tissue exhibiting nonlinear and time-dependent mechanical properties
Ulcerative melting keratitis is a pathological condition of the cornea where stromal damage is probably caused by an imbalance between proteinases and proteinase inhibitors, which are components involved in corneal wound healing
Fontanella et al BMC Vet Res (2021) 17:340 behaviour and stiffening with increasing intraocular pressure can be evaluated through inflation tests, while the stress-strain behaviour and the viscoelastic response in medium and long term can be evaluated in uniaxial tensile mode
Summary
Cornea is a composite tissue exhibiting nonlinear and time-dependent mechanical properties. Uniaxial tensile and stress-relaxation tests are developed to evaluate stress-strain and timedependent mechanical behaviour of porcine corneas. Ulcerative melting keratitis is a pathological condition of the cornea where stromal damage is probably caused by an imbalance between proteinases and proteinase inhibitors, which are components involved in corneal wound healing. This pathology alters the tissue microstructural configuration influencing its mechanical functionality. Fontanella et al BMC Vet Res (2021) 17:340 behaviour and stiffening with increasing intraocular pressure can be evaluated through inflation tests, while the stress-strain behaviour and the viscoelastic response in medium and long term can be evaluated in uniaxial tensile mode. The porcine and human cornea exhibit similar stress-strain behaviour under short- and long-term loading and react to sustained loading, the creep is higher in human than in porcine corneas [7]
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