• Retrobulbar injection of local anesthetic desensitizes the structures of the eye and paralyzes the external ocular muscles, providing a globe which is anesthetized and central.

Uses

• Historically, retrobulbar anesthesia was used as an adjunct for intraocular surgery to produce a centrally-positioned globe, but for this use it has largely been superseded by the use of neuromuscular blocking agents Anesthesia: non-depolarizing neuromuscular blockade.
• Still occasionally used as adjunctive agent for enucleation surgery Eye: enucleation.

Advantages

• Provides excellent peri-operative analgesia.

Disadvantages

• Inadvertent injection of local anesthetic agent into a blood vessel could lead to sudden death.
• Inadvertent injection of local anesthetic agent into the CSF surrounding the optic nerve could lead to respiratory arrest due to brainstem anesthesia.
• Risk of globe trauma if performed incorrectly. Prior to enucleation this complication is less of a concern unless endophthalmitis is present, in which case it risks local spread of infection.
• Risk of trauma to local tissues.
• Risk of initiation of oculocardiac reflex.

Alternative techniques

• Neuromuscular blockade Anesthesia: non-depolarizing neuromuscular blockade.

Time required

Preparation

• 5 min to prepare syringes and anesthetic.

Procedure

• 5 min to perform retrobulbar injections.

Decision taking

Criteria for choosing test

• Used infequently in small animal ophthalmology.
• Consider as peri-operative analgesia for enucleation surgery in cases where a lower plane of intra-operative anesthesia is desirable, or where optimal post-operative analgesia is indicated.

Risk assessment

• Procedure carries some risk.
• Always aspirate prior to injection to ensure needle placement is not within a blood vessel.