A retrobulbar block involves injecting local anesthetic behind the eyeball using a needle. The needle is inserted at an angle through the lower eyelid and advanced until it passes through two layers surrounding the eye. Anesthetic is then injected. For a peribulbar block, a small incision is made in the conjunctiva and Tenon's capsule. Blunt dissection is used to free a quadrant, and then anesthetic is injected behind the tissues surrounding the eye. Both blocks are alternatives to general anesthesia for eye surgeries and can last over four hours with the right mixture of anesthetics.

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RetrobulbarBlock,Peribulbar Block,and Common Nerve Blocks
ADMINISTERING LOCAL NERVE BLOCKS
The most common local anesthetic mixture is 2% lidocaine with 1:100,000 epinephrine to
provide some homeostasis. Addition of 0.5% bupivacaine will provide longer anesthesia (~6-8
hours) for lengthy procedures. The following diagrams illustrate common local nerve blocks
used in ophthalmology.
Diagram 1: Common Periorbital Nerve Blocks

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Diagram 2: Common Facial Nerve Blocks
ADMINISTERING THE RETROBULBAR BLOCK
Retrobulbar blocks are useful methods of achieving anesthesia for intraocular and orbital
surgeries. Blocks are good alternatives to general anesthesia when general anesthesia is
undesirable or contraindicated.
There are many techniques to administer a retrobulbar block. The method described here is
what I prefer. Depending on the type of anesthetic, a block may last over four hours with a
mixture of lidocaine 1% and bupivacaine 0.375%. Addition of hyaluronidase to the anesthetic
mix improves penetration of anesthesia.
 Clean the lower lid with an alcohol wipe.
 Have the patient look straight ahead.
 Use a 5 cc syringe and a 23 gauge, 1.5 inch flat grind needle.
 Start 2/3 lateral along the inferior orbital rim (inferior to the temporal limbus) with the needle
tip pointing perpendicular to the plane of the patient’s face. Place the index finger between
the globe and the infraorbital rim, elevating the globe.
 Stabilize with the little finger and hypothenar eminence firmly on the bones of the patient’s
cheek.
 Enter just inferior to the globe and perpendicular to the plane of the face.

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Figure 1: Retrobulbar Block - Step 1
 Once you feel the first pop through the orbital septum, angle 45 degrees medially and 45
degrees superiorly towards the apex of the orbit until the second pop through the muscle
cone is felt.
 Dr Boldt, moves the needle gently side to side while advancing beneath the globe. If the
needle begins to engage the globe, then the eye will start to move side to side. Hopefully,
one can stop advancing before globe perforation occurs. This move is controversial,
because some feel it leads to a higher rate of orbital hemorrhage. Dr Sutphin, suggests
watching for globe movement. The globe should rotate downward when you engage the
septum. As you go through, it should rotate back up. Failure to do so could suggest the
needle is in the sclera.
Figure 2: Retrobulbar Block - Step 2
 Pull back on the syringe to ensure the needle is not in a vessel, and then inject 3-5 cc of
anesthetic, palpating the globe to assess for posterior pressure.

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Figure 3: Retrobulbar Block - Injection
 After withdrawing the needle, apply firm pressure to the globe with a 4x4 gauze (enough
to occlude the central retinal artery) to tamponade any possible retrobulbar hemorrhage.
Provide firm pressure for 90-120 seconds. Some suggest alternating 10-15 seconds of
firm pressure with release of the pressure to allow perfusion of the central retinal artery.
Studies by Dr Hayreh, demonstrate that the retina is able to tolerate up to 90 minutes of
non-perfusion before permanent damage.

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ADMINISTERING THE SUB-TENONS PERIBULBAR BLOCK:
 A peribulbar block is an alternative to the retrobulbar block and offers an effective way to
provide anesthesia before ocular surgery
 A small button hole is made in the conjunctivae and Tenon's using Westcott scissors and
0.12 forceps (Figure 4).
Figure 4: Button hole formed ~10 mm from the corneal limbus
 The quadrant is freed using blunt dissection with Westcott scissors (Figure 5).
Figure 5: Freeing the Quadrant

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 1% lidocaine/0.375% bupivacaine is drawn up in a syringe attached to a blunt lacrimal
cannula (Figure 6) and then inserted posteriorly under the subtenons space (Figure 7).
Figure 6: Lacrimal cannula
Figure 7: Insertion of cannula and injection of anesthetic

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