1Osterholz J. E., 1,2Winter M., 3Pfister G.

1Klinik für Ophthalmologie der Christian-Albrechts-Universität zu Kiel, Hegewischstr. 2, D-24105 Kiel; 2Waller Heerstraße 154a, D-28219 Bremen; 3Institut für Angewandte Physik der Christian-Albrechts-Universität zu Kiel, Leibnizstr. 11-19, D-24118 Kiel

Intraocular long-term tamponades with perfluorocarbon liquids (PFCL) lead to retinal degenerations. Histological investigations indicate a mechanical damage of the retina. In order to estimate the mechanical forces occurring during PFCL tamponade the resultant pressure and shearing forces should be determined in model eyes.
Methods: At a model eye, the resultant pressure load during standardized movements (analogously to head turning movement) was determined with a pressure sensor at different measurement points. At a second experimental setup the liquid flow qualities of different PFCL were examined with in a transparent model eye. The resultant shearing forces on the boundary surface between retina and PFCL were calculated.
Results: The occurring pressures were dependent of the density of the PFCL and the filling volume. For every examined PFCL, the highest pressure in the static model was to be measured at the deepest point of the eye. In the dynamic model, the pressure peak shifted to the sidewall. The pressure peaks were between 314 Pa (2,4 mmHg) and 407 Pa (3,1 mmHg). For standardized acceleration, the size of the measured shearing forces was strongly dependent on the viscosity of the PFCL. The maximum shearing forces of the different PFCL were between 0,87 mN/m2 and 8055 mN/m2.
Conclusion: The resulting physical forces increase with the density and the viscosity of the inserted PFCL. Whether the relatively small physical forces are responsible for the incompatibility of the long-term tamponade with PFCL, is still undetermined.

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