To the Editor:
1The review article on ophthalmic regional anesthesia by Nouvellon et al. 1was engaging, particularly the cadaver photographs elucidating the spread of local anesthetic agent within the orbit as well as the links to supplemental digital content.
The authors are to be commended for their comprehensive discourse. However, their assertions regarding akinesia, reproducibility, and reblock rates for peribulbar (extraconal) anesthesia require greater clarification. A review of the literature, more current than quoted in their report, suggests the statement “an additional injection is required in as many as 50% of cases” may be misleadingly excessive.2–4
The efficacy and low complication rate of extraconal ophthalmic blockade is well documented. In a group of 200 patients, Ghali and Hafez2compared 5–7 ml peribulbar anesthesia using a single inferotemporal injection or a combined inferotemporal/superomedial technique. The reinjection rates for these two groups were 7% and 16%, respectively. Clausel et al. 3also evaluated single-shot peribulbar anesthesia for cataract surgery using local anesthetic volumes of 5–6 ml. Ninety of their 101 patients had complete akinesia at 10 min, and surgical conditions were deemed good in all cases. Similarly, Rizzo et al. ,4in a sample of 857 patients, evaluated the efficacy of a single injection of 2% lidocaine adopting a medial percutaneous approach. Akinesia was reportedly attained in 85.6% of patients 2 min after injection. Furthermore, surgical anesthesia was adequate in 100% of cases within 7 min, and no patients required block supplementation. By contrast, Luchetti et al. 5compared the efficacy of ropivacaine 0.75% and bupivacaine 0.5%-mepivacaine 2% in a study sample of 2,000 patients. They achieved satisfactory sensory blockade in all cases but noted a reinjection rate of 30–34% to attain complete eye immobility.
In terms of akinesia and reproducibility, the ultimate efficacy of local anesthetic infiltration into the extraconal space (peribulbar ophthalmic anesthesia) is governed by a number of factors. These include technique style (e.g. , intraorbital position of needle tip), composition of local anesthetic solution, use of the spreading agent hyaluronidase, and the nature and duration of the specific ophthalmic surgical procedure.
University of Miami, Bascom Palmer Eye Institute, Miami, Florida. email@example.com