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A. Gonzalez, J. D. Barbosa, A. Ray, S. Morales, J. D. Weiland, M. Humayun; Distance Measurement Between an Electrode and the Retina Using OCT Images. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1788. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the correlation between electrical impedance of an intraocular microelectrode and the electrode retina distance measured by optical coherence tomography (OCT)
Experiments were done in normal rats (n=2). Baseline OCT images were acquired prior to insertion of the microelectrode in the rat eye. Electrode insertion is made with a 75 um diameter platinum electrode. The electrode was advanced until it was visible in the fundus view of the OCT system. The scan line was adjusted to be along the length of the microelectrode to allow simultaneous scanning of the electrode tip and the retina. Electrical impedance was measured using a 10mV sine wave at 100KHz. Impedance and OCT data were acquired as the electrode was advanced towards the retina, under micromanipulator control.
The impedance increased consistently as the electrode was advanced towards the retina. This is illustrated in the graph below; values of impedance and distance have been normalized to the starting value of each. Distance equals zero represents the electrode tip in contact with the retina. Data represented as mean ± s.d
Increasing electrical impedance is proportional to how close the electrode is to the retina. Electrical impedance can be used to sense proximity to the retina.
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