Retrobulbar anesthesia

Demediuk OM, DhaMwal RS, Papworth DP, et al.A comparison of peribulbar and retrobulbar anesthesia for vitreoretinal surgical procedures.Arch Ophthalmol 1995 113 908-913. 

Feibel RM. Current concepts in retrobulbar anesthesia. Surv Ophthalmol 1985 30 102-110. 

Cataract patients, in general, have relatively little immediate postoperative pain. This absence of pain is, at least in part, due to the long duration of action (up to 12 hours) of bupivacaine used in retrobulbar anesthesia. Some practitioners recommend the use of oral analgesics, such as acetaminophen or ibuprofen, as needed, if the patient experiences minor discomfort in the immediate postsur-gical period.Topical NSAIDs are also reported to decrease immediate postoperative pain. Significant or persistent postoperative pain is considered to be abnormal and may be a symptom of such complications as corneal abrasion, bullous keratopathy, high lOP, or endophthalmitis. 

Retrobulbar anesthesia, competently administered, is a safe procedure. In 13 000 patients in whom a curved needle technique was used, the only serious complication was a single case of postoperative ischemic neuropathy (296). However, other centers have experienced recurrent problems with chemosis (up to 30%), sub-conjunctival hemorrhage, and lid hemorrhage before perfecting their technique (SEDA-18, 144). 

Retrobulbar anesthesia can lead to serious systemic toxicity. However, in animal studies accidental intravit-reous spread of lidocaine, bupivacaine, or a mixture of the two did not cause long-term retinal damage (308). 

Peribulbar anesthesia is generally considered safer than retrobulbar anesthesia, with a lower incidence of adverse effects. It avoids deep penetration of the orbit and therefore inadvertent subarachnoid injection. It also seems to be safer with regard to the risk of bulb perforation (314). 

Wittpenn JR, Rapoza P, Sternberg P Jr, Kuwashima L, Saklad J, Patz A. Respiratory arrest following retrobulbar anesthesia. Ophthalmology 1986 93(7) 867-70. 

Labelle PF, Lapointe A, Boucher MC. Vitreous hemorrhage following retrobulbar anesthesia. Can J Ophthalmol 1996 31(1) 21. ... 

Maintaining a deep anterior chamber can be considered the conditio sine qua non for successful anterior segment intraocular surgery. There are diverse pre- and intraoperative precautionary measures available to achieve this oculopression, addition of adrenalin and hyaluronidase to retrobulbar anesthesia, hyperventilation and blood pressure reduction during anesthesia, closed system operation as made possible by phacoemulsification (lens nucleus disintegration via ultrasound), or by intravenous infusion of hyperosmolar substances (Voros-marthy, 1967 Kelman, 1967). 

Compared with the retrobulbar technique, peribulbar anesthesia provides similar anesthesia and akinesia for both anterior segment and vitreoretinal surgical procedures, but some patients may have inadequate akinesia and require additional injections. In addition, the onset time of blockade is not as rapid as with retrobulbar injection. Nevertheless, peribulbar anesthesia reduces the potential for inadvertent globe penetration, retrobulbar hemorrhage, and direct optic nerve injury. Although serious problems with retrobulbar and peribulbar injections are uncommon, numerous complications have been reported (Box 3-3). 

Teichmann KD, Uthoff D. Retrobulbar (intraconal) anesthesia with a curved needle technique and results. J Cataract Refract Surg 1994 20(l) 54-60. 

Retrobulbar injection probably offers little therapeutic advantage over the combined subconjunctival and parenteral routes. This route is recommended only for regional anesthesia of the orbit, particularly to supplement general anesthesia (Miller 1992). 

BLIND AND PAINFUL EYE Retrobulbar injection of either absolute or 95% ethanol may provide relief from chronic pain associated with a blind and painful eye. Retrobulbar chlorpro-mazine also has been used. This treatment is preceded by administration of local anesthesia. Local infiltration of the ciliary nerves provides symptomatic relief from pain, but other nerve fibers may be damaged, causing paralysis of the extraocular muscles, including those in the eyelids, or neuroparalytic keratitis. The sensory fibers of the ciliary nerves may regenerate, and repeated injections sometimes are needed. 

Among the novel routes, subconjimctival injection allows circumvention of the barriers imposed by cornea and conjunctiva, resulting in higher levels in vitreous. The sub-tenon route is a good alternative to retrobulbar and peribulbar ones for administration of anesthesia due to less complications and avoidance of sharp needles. 

Barbiturates also affect extraocular muscle motion with down rotation of the eye and mydriasis during phase II of anesthesia and myosis in phase III. Thus it is necessary to make a retrobulbar injection with saline to maintain the cornea in front of the eyelid opening. It has also an effect on the ocular motion and nystagmus is observed during phase II of anesthesia. 

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