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Correspondence  |   December 2001
Ophthalmic Blocks at the Medial Canthus
Author Affiliations & Notes
  • Jacques Ripart, M.D., Ph.D.
    *
  • *Centre Hospitalier Universitaire de Nîmes, Nîmes, France. jacques.ripart@chu-nimes.fr
Article Information
Correspondence
Correspondence   |   December 2001
Ophthalmic Blocks at the Medial Canthus
Anesthesiology 12 2001, Vol.95, 1533-1535. doi:
Anesthesiology 12 2001, Vol.95, 1533-1535. doi:
In Reply:—
We thank Dr. Lopatka et al.  for their interest in our work and for their pertinent comments. The main concern is the difference between the technique described by Hustead et al.  1 that Dr. Lopatka et al.  seem to use and our technique. 2–7 They are very different. Hustead uses a peribulbar (extraconal) injection. The local anesthetic is injected into the extraconal space, a part of the corpus adiposum of the orbit. This is a different route of injecting into the same space than when performing classic inferolateral peribulbar anesthesia. Using the technique of Hustead, the needle is inserted medially to the caruncle, at the medial end of the lid aperture, near the junction between the lacrimal portion of the inferior and superior lids (fig. 1). Our technique is an episcleral (sub-Tenon) injection. The needle is inserted more laterally, tangentially to the globe, directly into the episcleral space (fig. 1). As we stated in our first article 2 when we began using this technique, we were convinced that it was another peribulbar approach, similar to the technique of Hustead. However, after intensive anatomic works, 6,7 we found that the two spaces of injections are different. Peribulbar injection results in a spread of the local anesthetic into the whole corpus adiposum of the orbit, including the intraconal space in which are located all the sensory and motor nerves that must be blocked to ensure good akinesia and analgesia of the eyeball 8 (fig. 2B). This spread is sometimes uncertain or incomplete, explaining some partial failures of peribulbar anesthesia. Injecting into the episcleral space forces the spread of the local anesthetic circularly around the scleral portion of the globe, thus encountering the ciliary nerves just before they enter the sclera and accounting for a good sensory block (fig. 2C). There is a continuity between the fascial sheath of the eyeball (the Tenon capsule) and the sheaths of the recti muscles. Thus, injecting into the episcleral space also guides the spread of the local anesthetic into the sheaths of the recti muscles, where it encounters the terminal motor nerves, accounting for a good akinesia of the globe. Because the fascial sheath of the eyeball fuses anteriorly with the bulbar conjunctiva, episcleral injection results in subconjunctival infiltration (chemosis). Finally, the excess local anesthetic flows into the lid, thus preventing blinking. This difference between the techniques explains the greater efficacy of our technique as compared with classic peribulbar injection. 5 However, there is a small difference in the position of the needle between the technique of Hustead and our technique. A small misplacement of the needle during an intended Hustead approach may result in episcleral injection, and conversely, Dr. Lopatka outlines that an intended peribulbar anesthesia occasionally produces chemosis, which is the indicator of episcleral injection.
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
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Fig. 2. (A  ) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B  ) Same view as A  , with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C  ) Same view as A  , with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
Fig. 2. (A 
	) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B 
	) Same view as A 
	, with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C 
	) Same view as A 
	, with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
Fig. 2. (A  ) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B  ) Same view as A  , with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C  ) Same view as A  , with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
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The work of Vohra and Good 9 has outlined the interest of the medial canthus for preventing inadvertent globe perforation. One of the main risk factors of perforation is myopic staphyloma, which is frequently located posteriorly to the globe (with an increased risk of retrobulbar injection) or inferiorly (with an increased risk of inferolateral peribulbar injection) but very infrequently on the medial part of the globe. Theoretically, this should be an argument in favor of the safety of medial canthus approaches. However, introducing a needle into the orbit has its own hazards. Safety of eye blocks depends mainly on skill, experience, and strong anatomic knowledge.
References
Hustead RF, Hamilton RC, Loken RG: Periocular local anesthesia: Medial orbital as an alternative to superior nasal injection. J Cataract Refract Surg 1994; 20: 197–201Hustead, RF Hamilton, RC Loken, RG
Ripart J, Lefrant JY, Lalourcey L, Benbabaali M, Charavel P, Mainemer M, Prat-Pradal D, Dupeyron G, Eledjam JJ: Medial canthus (caruncle) single injection periocular anesthesia. Anesth Analg 1996; 83: 1234–8Ripart, J Lefrant, JY Lalourcey, L Benbabaali, M Charavel, P Mainemer, M Prat-Pradal, D Dupeyron, G Eledjam, JJ
Ripart J, L’Hermite J, Nouvellon E, Charavel P, Jaussaud A, Dupeyron G, Eledjam JJ: Regional anesthesia for ophthalmic surgery performed by Single episcleral (sub-Tenon) injection: A 802 cases experience (abstract). Reg Anesth 1999; 24 (suppl 3): A59Ripart, J L’Hermite, J Nouvellon, E Charavel, P Jaussaud, A Dupeyron, G Eledjam, JJ
Ripart J, Lefrant JY, L’Hermite J, Borzli F, Nouvellon E, Fabbro-Peray P, Dadure C, Jaussaud A, Dupeyron G, de LA Coussaye JE, Eledjam JJ: Caruncle single injection episcleral (sub-Tenon) anesthesia for cataract surgery: Mepivacaine versus a lidocaine-bupivacaine mixture. Anesth Analg 2000; 91: 107–9Ripart, J Lefrant, JY L’Hermite, J Borzli, F Nouvellon, E Fabbro-Peray, P Dadure, C Jaussaud, A Dupeyron, G de LA Coussaye, JE Eledjam, JJ
Ripart J, Lefrant JY, Vivien B, Fabbro-Peray P, Charavel P, Jaussaud A, Dupeyron G, Eledjam JJ: Ophthalmic regional anesthesia: Canthus episcleral anesthesia is more efficient than peribulbar anesthesia: A double-blind randomized study. A nesthesiology 2000; 92: 1278–85Ripart, J Lefrant, JY Vivien, B Fabbro-Peray, P Charavel, P Jaussaud, A Dupeyron, G Eledjam, JJ
Ripart J, Prat-Pradal D, Charavel P, Eledjam JJ: Medial canthus single injection episcleral (sub-Tenon) anesthesia anatomic imaging. Clin Anat 1998; 11: 390–5Ripart, J Prat-Pradal, D Charavel, P Eledjam, JJ
Ripart J, Metge L, Prat-Pradal D, Lopez FM, Eledjam JJ: Medial canthus single injection episcleral (sub-Tenon) anesthesia computed tomography imaging. Anesth Analg 1998; 87: 43–5Ripart, J Metge, L Prat-Pradal, D Lopez, FM Eledjam, JJ
Ripart J, Lefrant JY, de La Coussaye JE, Prat-Pradal D, Vivien B, Eledjam JJ: Peribulbar versus  retrobulbar anesthesia for ophthalmic surgery: An anatomical comparison of extraconal and intraconal injections. A nesthesiology 2001; 94: 56–62Ripart, J Lefrant, JY de La Coussaye, JE Prat-Pradal, D Vivien, B Eledjam, JJ
Vohra SB, Good PA: Altered globe dimensions of axial myopia as a risk factors for penetrating ocular injury during peribulbar anesthesia. Br J Anaesth 2000; 85: 242–5Vohra, SB Good, PA
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
Fig. 1. Site of introducing the needle. 1 = Site of introducing the needle for the technique of Hustead; 2 = caruncle; 3 = semilunaris fold of the conjunctiva; 4 = site of introducing the needle for our technique.
×
Fig. 2. (A  ) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B  ) Same view as A  , with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C  ) Same view as A  , with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
Fig. 2. (A 
	) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B 
	) Same view as A 
	, with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C 
	) Same view as A 
	, with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
Fig. 2. (A  ) Semischematic view of a horizontal section of the orbit. 1 = Common insertion of bulbar conjunctiva and Tenon capsule on the eyeball, near the sclerocorneal limbus; 2 = anterior facial sheath of the eyeball (the Tenon capsule); 3 = sclera; 4 = medial rectus muscle; 5 = episcleral space (sub-Tenon); 6 = posterior facial sheath of the eyeball; 7 = lateral rectus muscle. Note the continuity between the Tenon capsule and the sheaths of the rectus muscles. (B  ) Same view as A  , with figurated spread of a local anesthetic injected into the peribulbar space, with subsequent spread into the muscular cone. Because the space for spreading is the adipose tissue of the orbit, including small septas network, this spread may be incomplete or heterogeneous, thus accounting for imperfect blocks. (C  ) Same view as A  , with figurated spread of a local anesthetic injected into the episcleral (sub-Tenon) space. Note the spreading into the whole episcleral space and into the sheaths of the rectus muscles, thus accounting for good akinesia. Because the episcleral space is adherence-free and septum-free, this spread is more constant, thus accounting for more constant akinesia. Additionally, because the anterior Tenon is not tightly sealed, part of the local anesthetic flows to the lids, accounting for akinesia of the orbicularis muscle.
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