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L.A. Mawn, D.R. Sztipanovits, R.L. Galloway; Development of a Navigational System for Orbital Endoscopy . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3784.
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© ARVO (1962-2015); The Authors (2016-present)
We developed an orbital endoscope for use with the free electron laser. Our previous studies evaluated visualization media, surgical technique modification in cadavers and then a live animal model. This study was conducted to develop an intraoperative navigational system for orbital enodscopy.
An experimental study utilizing an electromagnetically tracked orbital endoscope was performed. The accuracy and precision of the magnetic tracker, the fiducial registration error (FRE), and target registration error (TRE) were first studied. A phantom was then constructed to represent a model globe and optic nerve within a skull. Bone fiducials were implanted in four locations as markers for registration. CT scans were obtained. The fiducials were located and recorded in image space. The coordinates of these fiducials were obtained with the tracker and the volumes were mapped to physical space. The catheter was then guided through the orbit to locate the optic nerve. The catheter was then mounted to the endoscope and the nerve again located.
The accuracy studies of the electromagnetic catheter found an average distance error of 2.583 +/– 1.792 mm. The precision studies of the catheter showed ranges of each coordinate far less than 0.5 mm. When the electromagnetic catheter system was compared to the Optotrack system, the average FRE was 2.73 +/– 0.98 mm, the average TRE was 3.76 +/– 1.21 mm. In the phantom trials, the RMS error was consistently between 2 and 3 mm.
This study suggests that there is a future for electromagnetic tracking in orbital endoscopic surgery
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