Читать книгу Complications in Equine Surgery - Группа авторов - Страница 261

Using short‐beveled (spinal needle) and shorter needles decreases the chance of puncturing the optic nerve sheath. Using the lowest effective volume (recommended 8–10 ml for a standard size horse) reduces the caudal spread toward the brain in case of puncture.

Of the three techniques described in horses to perform a retrobulbar block: four‐point block; modified Peterson; and injection into the orbital fossa above the dorsal orbital rim and zygomatic arch, the latter has been suggested to decrease the risk of optic nerve penetration. Ultrasound‐guidance during placement of the needle within the retrobulbar muscle cone may increase not only the effectiveness but also the safety of this block if the optic nerve is visualized and avoided [99]. Resistance during injection of the local anesthetic may be due to intraneural injection, in which case it should be immediately stopped and needle repositioned.