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Anaesthesia: Approaches and Limitations
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
Retrobulbar block. In this approach, the anaesthetic agent is injected into the retrobulbar space using a 1½-inch, 23G needle or a specific, commercially available retrobulbar needle. The mechanism of action through which analgesia and akinesia are achieved is by the effect on the ciliary ganglion [wherein parasympathetic fibres relay and sympathetic fibres pass by] and on the nerves supplying the extraocular muscles at the orbital apex. The main advantages of this method were that it is a one-point injection, and a relatively low volume of anaesthesia is needed [about 2–3 cc]. There were innumerable disadvantages, though, some of a very serious nature. These disadvantages include globe perforation, retrobulbar haemorrhage, optic nerve injury, and very rarely the risk of intracranial escape [through the orbital apex] and seizures. In addition, the anaesthesia has a shorter duration of action. Hence, this route of ocular anaesthesia is no longer recommended.
Head and Neck
Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
All the nerves responsible for the sensory, motor and autonomic innervation of the eyeball transit through the intraconal space (except the trochlear nerve and branch of the facial nerve). Whatever the technique, the local anaesthetic injected must spread into the cone for a successful block. This explains why the retrobulbar block has a faster onset whilst in the peribulbar block the local anesthetic injected extraconally needs time to spread into the cone to produce the effect. This can be overcome by increasing the volume of local anaesthetic injected.
Local Anesthetics
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Elena González Burgos, Luis Luis García-García, M. Pilar Gómez-Serranillos, Francisca Gómez Oliver
Myotoxicity, first described more than 55 years ago by Brun (Brun, 1959), after peri- and retrobulbar block during ophthalmologic procedures relates to a great occurrence of muscle dysfunction. Even though all clinically used LAs may cause skeletal muscle injury, even leading to muscle necrosis, tetracaine, and procaine are less disposed to myotoxicity. By contrast, bupivacaine seems to be the LA with higher toxicity. Nevertheless, the myonecrosis of skeletal muscle is an unusual side effect that in most cases is reversible (Dippenaar, 2007). The severity of the damage is dose-dependent. Furthermore, it worsens when the LA is administered by continuous infusion or when serial injections are done. After injection, there is hypercontraction of the myofibrils that over the next 1–2 days is followed by lytic degeneration of the sarcoplasmic reticulum (SR), myocyte edema, and necrosis. In most cases, the muscle fibers regenerate within 3–4 weeks. Nonetheless, the concomitant administration of epinephrine and corticosteroids potentiates the severity of myotoxicity, even leading to permanent muscle damage.
Retroauricular myoperiosteal autograft for orbital implant exposure: 11 years of experience
Published in Orbit, 2020
Ramón Medel, Maria Vittoria Cicinelli, Johana Catalina Arboleda Hurtado, Juan Carlos Sánchez España, Alejandra Tapia Bahamondes, Luz María Vasquez
All surgeries were performed under local anesthesia with sedation by a single experienced surgeon (R.M.). For both retroauricular anesthesia and retrobulbar block, a 5 mL-injection of bupivacaine hydrochloride 0.5% mixed with 1:200,000 units of adrenaline was given. To prepare the recipient bed, the attached edges of the conjunctiva and Tenon’s fascia were freed from the implant surface and carefully lifted, and the defect was callipered to determine the graft size to be harvested. The exposed surface of the implant was smoothed using a 15° blade (in cases of a porous polyethylene ball) or burred back with a power drill (in cases of a hydroxyapatite or bioceramic implant). Irrigation cycles with abundant saline solution and suction were repeated for washout of necrotic debris from the sphere. Finally, an antibiotic solution (vancomycin and ceftazidime, 2 ml) was injected into the anophthalmic socket.
Efficacy of Intravitreal Dexamethasone Implant in Patients of Uveitis Undergoing Cataract Surgery
Published in Ocular Immunology and Inflammation, 2019
Gaurav Gupta, Jagat Ram, Vishali Gupta, Ramandeep Singh, Reema Bansal, Parul Chawla Gupta, Amod Gupta
Patients were admitted one day prior to surgery (if needed) or surgery was done on day care basis or on outpatient basis. Same experienced surgeon (JR) performed all the surgeries, strictly adhering to principles of closed chamber technique in both the groups. Written informed consent was taken from every patient before the surgery. All surgeries were performed under local anesthesia using peribulbar or retrobulbar block. After adequate anesthesia, intravitreal 700 µg dexamethasone implant was given 3.5 mm away from the limbus inferotemporally in DEXA implant group patients only. Two side port incisions were created at 9 and 2 o’clock position using 15° disposable knife and main port was made using 2.2 mm disposable keratome. The anterior chamber was formed using high viscosity viscoelastic (1.4% sodium hyaluronate). Small pupils were managed using Iris hooks or Malyugin’s ring. A 5–5.5 mm continuous circular capsulorrhexis was made using Uttrata’s forceps. In cases of white cataract, trypan blue dye (0.06%) was used to stain anterior capsule. Cortical cleavage hydrodissection was performed with nuclear rotation. Lens nuclear emulsification was done by phacoemulsification. The cortical matter was removed by bimanual irrigation-aspiration (I/A). Foldable hydrophobic acrylic IOL was implanted in the capsular bag in all cases. A subconjuctival injection of gentamycin (20 mg) and dexamethasone (4 mg) was given at the end of surgery.
Diplopia after Cataract Extraction
Published in Seminars in Ophthalmology, 2018
Marc A. Bouffard, Dean M. Cestari
It may be difficult to tell whether there is an advantage in the choice of retrobulbar or peribulbar block as a means to mitigate the chance of postoperative diplopia. Capo, Roth, and Johnson found no difference in the frequency of postoperative diplopia between patients anesthetized with retrobulbar versus peribulbar blocks among 19 patients.14 Conversely, seven of the nine patients in Esswein and von Noorden’s smaller series of patients with postoperative diplopia received peribulbar blocks.15 Given the longer needle length and trajectory required to administer a retrobulbar block, one might assume a resultant increase in the probability of injuring either the cranial nerves or the extraocular muscles. It might also be assumed that the shorter needle and extraconal target of a peribulbar block might confer less risk of direct trauma or anesthetic-related myotoxicity. However, peribulbar blocks typically require a larger volume of anesthetic than is used in retrobulbar blocks to achieve adequate analgesia, thus anesthetic myotoxicity may be just as potent. It is important to note that injury to cranial nerves or extraocular muscles is possible, even under circumstances of correct technical performance.