Evaluation of corneal biomechanical behavior using uniaxial tensile tests applied on fresh and cultured ex vivo models in healthy, injured and helium plasma treated populations

Corneal ulcers are one of the main ocular disorders. Low-temperature atmospheric pressure plasma (ionized gas) has been suggested as an innovative therapeutic approach for treating wounds in order to promote wound healing. The aim of this study was the characterization of corneal mechanical behavior in healthy, injured and helium plasma treated populations. This thesis is a component of a larger study: the research team also plans to conduct a histopathological and biomolecular examination of the samples in every population. 71 ex-vivo porcine models were evaluated by uniaxial tensile test to analyze stress-strain and stress-relaxation behavior. The samples were divided into two main populations: corneas that were considered healthy before slaughtering (H, healthy) and corneas that were injured with alkaline solution after enucleation to create an experimental ulcer (L, lesionated). Within the two main population corneas were tested in two different conditions: fresh, a few hours after enucleation (F, fresh), and cultured for seven days in a specific medium (C, cultured). Furthermore, another condition was considered: every population underwent or not the helium plasma treatment for 2 minutes (P2) and for 4 minutes (P4). According to early findings, the most rigid corneas are those that were examined just a few hours after enucleation in their undamaged form. When compared to their fresh counterparts, healthy cultured corneas showed less stiffness, indicating that the medium had an effect in reducing corneal rigidity. It was also shown that samples treated with plasma were stiffer than untreated injured samples but less stiff than healthy samples. The corneas that received the 2-minute treatment were not so distant from the samples with the injuries that had not been treated, but the ones that received the 4-minute treatment had a remarkable increase in stiffness. This treatment appears to be effective and promising for treating corneal diseases in domestic animals, according to these first data, and it could end up being a successful therapy.