Experiences with the local retrobulbar anesthesia in ophthalmologic surgery of the standing horse. [German]Original Title Erfahrungen mit der retrobulbaren Anasthesie bei Augenoperationen am stehenden Pferd.

摘要

Local retrobulbar anesthesia of the optic nerve is performed with a hypodermic needle 20 G, 70 mm, or with a flexible catheter pushed through a Tuohy epidural needle. The local anesthetic agents cause analgesia extending to the anterior ocular parts, including cornea and conjunctiva. Furthermore, a total akinesia of the globe and a sensory block of the optical nerve are induced, with a reversible loss of vision. Unlike in humans, there are only few blood vessels near the injection site in horses. This was approved by initial examinations with ultrasound (including colour flow Doppler), computed tomography, and anatomical preparation. No serious hemorrhage or other complications hazardous to vision or life could be seen. Ocular surgery in the standing horse with selective nerve blocks is indicated in all horses classified as high-risk patients, especially in geriatric horses. Meanwhile there are several surgical procedures that can be performed with the same accuracy and quality as under general anesthesia, besides the established enucleation. The long-lasting analgesic effect after pre-surgical administration, which is far longer than the pharmacological effect, is an additional benefit of local retrobulbar anesthesia.