Investigation of long term drift of an intraocular pressure sensor

“Zero drift” behavior of an optical intraocular pressure sensor is studied using an analytical model based on the deflection of a circular membrane. Results from the analytical model were verified with experimental results from “bulge” testing. The analytical model was used to study the zero drift of the sensor as a function of changes in membrane thickness, geometry of the sensor and amount of gas inside the cavity of the sensor. The results show that dissolution of the membrane, swelling of the spacer layer and oxidative aging can contribute significantly to zero drift of the sensor over time. The results are useful in guiding design and fabrication optimization to minimize drift in intraocular pressure sensors used for long term implantation.