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| Author(s): |
Alexandre Augusto Franchi de Barros Sobrinho
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2019-05-08. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2019-04-05 |
| Advisor: | José Luiz Laus |
| Abstract | |
Membranes based on type I collagen extracted from bovine superficial digital flexor tendon were studied as a possible raw material for making corneal inlays. They were implanted in the right-eye, on the corneal stroma of 16 New Zealand White rabbits, male or female, adults, in apparently systemic health. A "pocket" was created in the central region of the cornea for implantation and positioning of the membrane (inlay) within the anterior stroma (CM group, 16 rabbits). Corneas with pocket, without implantation of membranes (SM group, 16 rabbits), as well as intact corneas (control group, 4 rabbits without any surgical procedure) were studied. The CM and SM groups were clinically evaluated for the presence of blepharospasm, conjunctival hyperemia, edema, ocular secretion and neovascularization, and on the refractive properties and curvature of the cornea immediately before (baseline) and after 3, 7, 14, 21 and 28 days of the postoperative period. Four animals, randomly choose from CM and SM groups were submitted to active euthanasia at different times to harvest the corneas, which, together with intact corneas from the control group, were processed for comparative studies in optical anisotropy (total, form and intrinsic birefringences). All continuous variables were tested for statistical normality. Differences with p <0.05 were considered significant. Surgical procedures performed on the corneas of the SM group did not alter the refraction (p = 0.479). The corneas in the CM group presented with altered hipermetropy, astigmatism and sferical equivalent (vs. basal) from the third postoperative day (p <0.01) onwards, and those changes were maintained until the twenty-eighth day of evaluation. The corneal curvature was not altered by the procedures performed in the SM (p = 0.3) and CM (p = 0.28) groups. Elevations in total and form birefringence of the corneas were observed in the CM and SM groups at the different evaluated times, compared to the corneas in the control group. The proportions of increase of total birefringence were 4.15%, 2.98%, 2.99% and 2.79% in the CM group and 2.76%, 0.19%, 3.14% and 3, 36% in the SM group at 7, 14, 21 and 28 postoperative days, respectively. The intrinsic birefringence values oscillated in the studied groups and between the different evaluation times, representing changes in turnover associated with stromal remodeling. The collagen membrane, on the histopathological evaluation, was shown to be safe, to have a slow degradation time, to be non-toxic and biocompatible with rabbit corneal tissue. In addition, it altered both the corneal refraction and the total birefringence in the short term, but without altering the corneal curvature. It is, therefore, a promising material for future studies aiming the improvement and use as an inlay. (AU) | |
| FAPESP's process: | 16/00743-1 - Anisotropic and refractive properties of the cornea of rabbits following implantation of type I collagen inlays extracted from bovine digital flexor tendon |
| Grantee: | Alexandre Augusto Franchi de Barros Sobrinho |
| Support Opportunities: | Scholarships in Brazil - Doctorate |