97th DOG Annual Meeting 1999
RETINAL PRESSURE INDUCED BY PERFLUORODECALIN
M. Winter1, S. Behrendt1, D.-H. Menz2, G. Pfister3
Perflourocarbon liquids (PFCL) are used as an intraoperative tool to stabilize and reattach the retina. Used as long-term tamponade they induce retinopathy. Until today it remains uncertain whether the observed lesions depend on compression on the retina by the high specific gravity of the PFCL or on a disturbance of the retinal metabolism. To develop modified heavy liquids as a long-term tamponade the origin of the retinopathy has to be clarified. The purpose of this study was to determine the static and dynamic pressure on the retina by intraocular PFCL.
Material and method: An eye-model with a cavity matching the size of the human vitreous was filled with Ringers solution and fixed on a helmet of a test-person. The distance of the eye model and the eye of the test person to his longitudinal axis was equal. Ringers solution was exchanged to 25, 50, 75 or 100% perfluordecalin (PFD, specific gravity: 1,94g/cm3). Using a piezoresistive pressure sensor connected to an amplifier and computer based recorder the pressure at 14 different loci at the inner surface of the model-eye could be determined during different body movements (e.g. head turns, walking, skipping).
Results: The highest pressure was measured on the lower pole of the model eye with 50% PFD-tamponade during skipping movement with 829 Pa
(6,2mmHg). During head turns the pressure maximum temporal was
183 Pa (1,4mmHg).
Conclusions: In comparison with forces on the retina which occur during external acceleration (e.g. as car driver) the high specific gravity of the PFD results in relatively low pressure peaks during usual body movements. Therefore it seems improbable that the determined retinal pressure leads to the observed PFCL-induced retinopathy. It remains to be investigated to what extent parameters not included in this model (e.g. elasticity modules, shearforces) possibly may lead to a retinal damage.
1 Dept. of Ophthalmology, University Kiel, Hegewischstr. 2, D-24105 Kiel
2 Pharm Pur GmbH, Augsburg
3 Institut for Experimental and Applied Physics, University of Kiel
In cooperation with the "Arbeitsgemeinschaft für Glaskörperersatz"