What is a retrobulbar block?
Usually, lidocaine with epinephrine is injected into the retrobulbar space, which is the area located behind the eyeball (globe). It numbs the muscles around the eye by blocking cranial nerves II, III, and VI. This numbs the eye and also paralyzes the eye muscles temporarily so the eye does not move during the procedure. Retrobulbar block also helps numb the eye’s cornea, uvea, and conjunctiva by blocking the ciliary nerves.
Retrobulbar block was the standard procedure for anesthetizing the eye, however, another technique called peribulbar anesthesia (PBA) is becoming the preferred method because there is less chance of injuring the eye and the structures behind the globe (optic nerve and eye muscles) during the procedure.
What is a retrobulbar block used for?
How do doctors perform retrobulbar block?
To perform the retrobulbar block:
- The patient is first placed laying on their back, staring up at the ceiling
- Mild sedation such as propofol or midazolam is often administered intravenously
- The surface of the eye is numbed with topical anesthesia (usually tetracaine or similar medications)
- A local anesthetic (lidocaine, also frequently used in a mixture with bupivacaine) is injected behind the eyeball (globe)
- To decrease the chance of bleeding, ocular compression (the doctor applies pressure to the eyeball) may be performed a few seconds at a time for up to two minutes
There are alternatives to using the retrobulbar block, including:
- Topical anesthesia using drops applied to the surface of the eye is commonly used in cataract surgery.
- Peribulbar block is similar to the retrobulbar block but the anesthetic is administered in a different area of the eye and is less likely to damage important eye structures.
- Sub-Tenon block involves the use of topical anesthetic drops and an anesthetic injection to the eye.
- General anesthesia is rarely used for eye surgeries except in complex cases.
How long does retrobulbar block last?
Depending on the type of anesthetic used, a retrobulbar block may be short-acting, lasting about 30 minutes, or long-acting, lasting about 6-8 hours.
What are risks and complications of retrobulbar block?
Retrobulbar block is generally well-tolerated. When complications do occur, they can include:
- Retrobulbar bleeding
- Optic nerve injury
- Eye redness
- Eye pain
- Dilated pupils/light sensitivity
- Allergic reaction to anesthetic
- Ocular perforation
- Respiratory depression or arrest
- Stroke in the eye
- Slow heart rate
- Eyelid drooping
- Double vision
- Corneal abrasion
- Subarachnoid or intradural injection (very rare)