28 марта 2022
DSTU SCIENTISTS DEVELOP A CORNEAL PROSTHESIS SUPERIOR TO THE EXISTING ANALOGUES IN CHARACTERISTICS
DSTU scientists work on creation of keratoprosthesis (corneal prosthesis) with better characteristics and low net cost.
Researchers are solving an uneasy problem: to choose the most suitable material fr om a large number of options, which presents a certain technological complexity.
- The main questions, wh ere we have to focus thoroughly, are identification of the mechanical properties of the cornea, selection of functionally graded porous materials (FGPMs), including polymeric ones made using 3D printing for the attachment structure of the optical part of the prosthesis, commented the project participant, head of the Department of Theoretical and Applied Mechanics of the DSTU Arkady Solovyov.
The cornea is an elastic, porous, fluid-filled material (poroelastic water-saturated material). It consists of several layers, and each layer has unique properties. In order to study all these properties, it is necessary to carry out a series of tests, including indentation (immersion of a rigid object in a material), which will determine the ratio of the applied force to the depth of penetration of the index and follow the changes on its surface.
The results of these tests will serve as additional information for solving inverse problem of identifying the mechanical properties of the cornea. Having determined these properties, it will be possible to solve the direct problem of determination of the strain in the structural elements of their deformation and choosing the materials that can reduce the resulting strain.
- Solving a direct problem consists of several stages: mathematical modeling; geometric modeling - creating CAD models, Computer-aided design; analytical calculations in the form of formulas, as well as numerical calculations using CAE, Computer-aided engineering, said Arkady Soloviev. - In addition to mathematical and mechanical problems, our specialists calculate physical and chemical models using licensed ANSYS packages, a universal software system of finite element analysis.
According to scientists, "donor material is statistically less than it is needed" - in this case, it should be viable, biologically clean and correspond in physical characteristics to the recipient's cornea. As a result, the cost of transplanting a donor cornea costs an average of 300 000 rubles for the patient, in the absence of guarantees of its transparent engraftment. Therefore, it is important not only to create such an artificial prosthesis that will be as close as possible to the physical characteristics of the patient's cornea and guarantee the transparency of the optical zone, but also make it inexpensive.
In addition, it is necessary to solve the technical problem that ophthalmologist encountered when installing keratoprostheses: when the supporting part of the prosthesis interacts with the cornea, soft tissues become destroyed, and the prosthesis is pushed out by intraocular pressure. The task of scientists is to level these processes through the search for biocompatible materials and suitable fastening. For make in possible scientists use various materials, but their rigidity significantly exceeds the rigidity of corneal tissues. According to the project participants, a solution to this problem can be found when switching from metals to functional gradient polymers or by sharing both groups of materials.
In addition, researchers are working to enlarge the optical part of the artificial cornea and thereby expand the viewing angle. To prevent rejection or damage to the cornea in the area of contact with the optical part of the prosthesis, scientists plan to use an intermediate layer with radially inhomogeneous properties.
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