Finite element analysis of changes in tensile strain and deformation by airbag impact in eyes of various axial lengths.

PURPOSE: Airbags have substantially reduced mortality and morbidity, while ocular injuries caused by airbags have been reported. We applied a three-dimensional finite element analysis (FEA) model we have established for evaluation of the deformation of an intact eyeball of various axial lengths induced by an airbag impact at various impact velocities. METHODS: A model human eye we have created was used in simulations with an FEA program, PAM-GENERIS™ (Nihon ESI, Tokyo, Japan). The airbag was set to impact eyes with various axial lengths of 21.85 mm (hyperopia), 23.85 mm (emmetropia) and 25.85 mm (myopia), at initial velocities of 30, 40, 50 and 60 m/s. Changes in the shape of the eye and the strain induced were calculated. Deformation of the eye in a cross-sectional view was displayed sequentially in slow motion. RESULTS: We found that considerable damage, such as corneal or scleral lacerations, was observed especially at higher impact velocities, such as 50 or 60 m/s, in eyes with any axial length. Deformation was most evident in the anterior segment. The decrease rate of axial length was greatest in the hyperopic eye, followed by the myopic eye, and the emmetropic eye. CONCLUSIONS: It was shown that hyperopic eyes are most susceptible to deformation by an airbag impact in this simulation. The considerable deformation by an airbag impact on the eye during a traffic accident shown in this study might indicate the necessity of ocular protection to avoid permanent eye damage.

Analysis of Cytokine Production Profiles of Local and Systemic Lymphocytes in Sick Building Syndrome Compared with Ocular Allergy.

Purpose: We have previously studied clinical and allergological aspects of sick building syndrome (SBS) cases with ocular disorders and found that SBS is suggested to be partially induced by an allergic response. We analyzed the cytokine production profiles of conjunctival and peripheral blood lymphocytes in patients with SBS with ocular manifestations to further evaluate the pathophysiology of SBS from an immunological standpoint. Methods: We obtained conjunctival samples and peripheral blood mononuclear cells (PBMC) from 15 cases of SBS with ocular findings, 49 cases of allergic conjunctival diseases (ACD) (allergic conjunctivitis (AC), atopic keratoconjunctivitis (AKC), and vernal keratoconjunctivitis (VKC)), and normal controls. Frequencies of cytokine-producing T cells were analyzed by flow cytometry based on an intracellular cytokine staining method. Results: Although no significant difference was observed in the percentage of interferon (IFN)-γ-producing CD4+ T cells in PBMC between patients with SBS and controls, the percentage of interleukin (IL)-4-producing PBMC CD4+ T cells in patients with SBS was significantly higher than that in controls. The percentage of IL-4-producing CD4+ T cells in the conjunctiva in patients with SBS was significantly higher than that in controls, whereas it was significantly lower than that in AKC and VKC. A significant correlation was observed between the percentage of IL-4-producing CD4+ T cells in the conjunctiva and clinical score. Conclusion: These results suggest that SBS may be a kind of allergic disorder and that IL-4 plays a role in the development of allergic disorders in SBS ocular lesions.