Topical vs. Peribulbar vs. Lateral Retrobulbar vs. Medial Retrobulbar Ophthalmic Block
50% of cataract surgeries use topical blocks
Peribulbar/Retrobulbar Block Indications:
- Corneal transplant
- Complex cataract surgery
- Cataract operating time > 25 min
Topical Ophthalmic Block
Topical procedures in the OR and/or supplemental analgesia during surgery recommend using 2% Lidocaine preservative free as the eye drop, because preservatives can damage the endothelial cells of the cornea.
Intracameral injection (anterior or posterior chamber of the eye) or intraocular (intravitreal) injections by the surgeon, use 1% lidocaine preservative free with 1:100,000 epinephrine.
Peribulbar Extraconal Ophthalmic Block
27 gauge 1/2-inch needle with a larger volume (9-12 ml) with hyaluronidase. Results in minimal risk to patient and good akinesia, unlike topical anesthetic.
Topical Eye Drops
- Preoperative: Proparacaine (AK-Taine®) Ophthalmic 0.75% multidose vial, the manufacturer is Akorn®.
- Patient reclined in a comfortable position; instill 1 – 2 drops of proparacaine 0.75% ophthalmic drops in the lower conjunctival cul-de-sac.
- After administering the eye drop, close the eyelids for about 15 to 30 seconds before proceeding with the transconjunctival needle insertion. Avoid blinking, which moves tears/drug into the punctae.
Preparation of the RBB block local anesthetic solution
- Mix 5 ml of plain 0.75% bupivacaine (Marcaine®), 5 ml of plain 2% lidocaine and 20 IU of hyaluronidase, for a final 10 ml mixture of plain 0.375% bupivacaine/1% lidocaine with 2 IU/ml of hyaluronidase (2 to 3 hour of surgery time).
Ophthalmic Block Additives
Hyaluronidase Additive: Hyaluronan (hyaluronic acid) is a protective barrier in the interstitial tissue that prevents fluid and electrolyte shifts. Hyaluronidase (HYLENEX® Recombinant) is used as an adjunct with injectable anesthetic to enhance dispersion and target tissue absorption by breaking down hyaluronan. It also inhibits muscle activity.
Clinically, adding hyaluronidase results in a more consistent and rapid onset of the block and requires less injectate volume.
HYLENEX® Recombinant (150 USP units/ml) is the preservative free enzyme recombinant human hyaluronidase.
Hyaluronidase – Stabilized Solution (150 USP units/ml) is the preservative free preparation of highly purified bovine testicular hyaluronidase enzyme.
Epinephrine Additive: Avoid adding epinephrine because the ophthalmic literature has implicated epinephrine as a cause of ischemia to the orbital vessels especially in diabetics. However, practitioners routinely use epinephrine especially when 2% lidocaine is preferred for shorter cases.
Preservative Additive: Preservatives in the orbital blocks have not been implicated in adverse patient outcomes; local anesthetics have been used with preservatives without any adverse outcomes.