Retrobulbar Block

Definition

Cataract surgery is likely to remain the most frequently performed surgical procedure in industrialized nations with their burgeoning Baby Boomer populations. Yet many anesthesiologists are unaware of the potential sight- and life-threatening complications associated with ophthalmic regional anesthesia, either from a lack of technical familiarity or from a lack of follow-up in predominantly same-day surgical patients. Anesthesiologists must be aware of these rare but possibly fatal consequences of local anesthesia injected into a patient’s eye to anticipate complications and treat them appropriately.

A review of the literature reveals an evolving practice to less invasive ocular anesthesia. From Knapp’s use of 4% retrobulbar cocaine in 1884, Atkinson advocated the “modern” approach in 1936 of a blind insertion of a needle into the intraconal space. In 1986 Davis and Mandel described the posterior peribulbar technique as an alternative. In 1992 Stevens published an article about cataract extraction by a medial quadrant sub-Tenon capsular infiltration. Subconjunctival and topical anesthesia are useful in modern ophthalmic surgical techniques that do not mandate total ocular akinesia and analgesia.

Retrobulbar block combined with facial nerve block provides superior akinesia, anesthesia, and analgesia compared with other regional techniques. Indications include the following:

• Avoidance of general anesthesia in elderly patients who have multiple medical comorbidities

• Achievement of optimal surgical conditions for extracapsular cataract extraction, phacoemulsification, intraocular lens implantation, and open globe surgery (e.g., vitrectomy, glaucoma treatment, repair of retinal detachment)

• Prolonged, difficult surgeries (e.g., previous eye surgeries) or in patients with hard cataracts or nystagmus

Contraindications to retrobulbar block include the following:

• True allergy to local anesthetic drugs

• Patient refusal, despite explanations regarding the use of intravenous sedation to minimize pain and lack of perioperative awareness

• Patient inability to cooperate

The operating room team must determine its own level of comfort concerning contraindications to local anesthetic blocks. The spectrum of “uncooperative” patients includes impaired mental status, youth, dementia, deafness, severe emphysema or congestive heart failure, excessive anxiety, inability to keep still from Parkinson tremor or restless legs syndrome, or inability to lie flat. Which of these patients may be managed safely with regional anesthesia, minimal intravenous sedation, or verbal reassurance and which patients will require general anesthesia care should be answered by discussion among the ophthalmologist, anesthesiologist, and patient.

Coagulation abnormalities must also be considered. Evidence suggests that patients who take nonsteroidal antiinflammatory drugs, aspirin, or warfarin can undergo eye surgery safely.