Speaker
Description
In ocular biomechanics, the mechanical behaviour of the retina has received limited attention, as most studies have focused on the transduction of light into neuronal signals. Nevertheless, modelling retinal mechanics can provide valuable insights in the investigation of surgical procedures, such as subretinal injection, to evaluate the relevance of different surgical parameters on retinal rupture and detachment (L’Abbate, 2024). In this study, we propose a finite element model of the retina based on an innovative micromechanical approach, which focuses on the intrinsic discrete nature of the tissue seen as a network of structural elements and abandons more traditional continuum descriptions. The micromechanical model includes three layers: (i) a top network of trusses linking the top of the cells, modelling the internal limiting membrane, (ii) an intermediate layer consisting of vertical truss elements, representative of cells, such as cones, rods and Muller cells; and (iii) a bottom network of truss mimicking the bonds between cells at the interface with the retinal pigmented epithelium. The discrete geometry of the retina is generated with an ad hoc Matlab code, and numerical analyses are conducted with Abaqus. All structural elements are assumed to obey viscous-elastic constitutive laws. The elastic behaviours are modelled through Neo-Hookean materials, while the time-dependent behaviours through Prony series. The model has been used to simulate tensile and small punch laboratory tests on porcine retinas, revealing a better ability to capture the mechanical behaviour of the tissue with respect to alternative continuum models. Foreseen applications of the model include the simulation of the subretinal injection surgery, to assess the relevance of procedural variables such as injection rate, injection volume and absorption time on the retina.