A Multi-Electrode Electric Field Based Sensing System For Ophthalmic Anesthesia Training.

Local anesthesia administration prior to ophthalmic surgery involves inserting a syringe needle into a confined intraorbital space at the proper position, angle and depth. During this procedure ocular structures must remain unhurt and systemic complications must be avoided while achieving quick akinesia and analgesia. Animal cadavers do not emulate human anatomy accurately and human subject based training entails risk to the patient. Therefore, a training system that closely replicates the human ocular and orbital anatomy and provides the trainee with real-time feedback on the safety and effectiveness of the block administered would help reduce risks involved with real life procedures. This paper presents an anatomically accurate, rapid-prototyped manikin based training system for ophthalmic anesthetic blocks. The depth of penetration of the needle, the proximity of the needle to extraocular muscles and the touch of the needle to the muscles or optic nerve is detected by a multi-electrode electric field/capacitive sensing system. The eye structure of the manikin does not have any electrical connections to it, rendering it replaceable, thus, enabling the emulation of anatomical variations due to pathologies of the eye. A virtual instrument measures and computes the position of the needle and displays it to the trainee through an intuitive GUI with a 3D display of the orbital anatomy. The proposed capacitive sensing scheme has been validated by tests performed on a prototype system, thus demonstrating its usefulness for practical training purposes.