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Education  |   October 2014
Chemosis Secondary to Anterograde Episcleral (Sub-Tenon) Spread of Local Anesthetic during Retrobulbar Eye Block
Author Affiliations & Notes
  • Howard D. Palte, M.B.Ch.B., F.C.A. (SA)
    From the Department of Anesthesiology, Perioperative Medicine and Pain Management, Miller School of Medicine, University of Miami, Miami, Florida (H.D.P.).
  • Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).
    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • Address correspondence to Dr. Palte: hpalte@med.miami.edu
Article Information
Education / Images in Anesthesiology / Ophthalmologic Anesthesia / Pharmacology / Regional Anesthesia
Education   |   October 2014
Chemosis Secondary to Anterograde Episcleral (Sub-Tenon) Spread of Local Anesthetic during Retrobulbar Eye Block
Anesthesiology 10 2014, Vol.121, 877. doi:10.1097/ALN.0b013e3182a0594b
Anesthesiology 10 2014, Vol.121, 877. doi:10.1097/ALN.0b013e3182a0594b

Supplemental Digital Content is available in the text.

A PATIENT presented for enucleation of a blind, painful eye. After sedation, an appropriate orbital-rated 12–6 MHz L-25 ultrasound transducer (Sonosite, Bothell, WA) was positioned obliquely on the upper eyelid. The orbit and adnexa were identified, and a retrobulbar block was performed via an infero-temporal approach.1  The needle’s final position was confirmed on ultrasound. The spread of local anesthetic (LA) during the 8-ml injection was recorded (see Supplemental Digital Content 1, http://links.lww.com/ALN/A958).
Conjunctival edema (chemosis) is undesirable in cornea and glaucoma surgery as it distorts the surgical field. It occurs more often after peribulbar block than retrobulbar block. The commonly accepted pathogenesis is that local anesthetic flows anteriorly along the rectus muscles traversing through the insertion points between the sheaths and the conjunctiva/sclera.2  In sharp contrast, these ultrasound images (fig. and see Supplemental Digital Content 1, http://links.lww.com/ALN/A958) reveal an alternative mechanism for the deeper placed retrobulbar block. They illustrate that local anesthetic injected at the posterior pole of the globe distends the episcleral (sub-Tenon’s) space near the optic nerve root (fig. A), dissecting this plane open as it tracks forward to produce conjunctival edema at the globe’s anterior surface (fig. B). This reproducible ultrasound-derived finding has not been previously reported.3 
We present an alternate mechanism for eye block–induced chemosis by revealing that local anesthetic can access the episcleral space from behind the globe, dispelling the notion that conjunctival edema is purely an anterior segment phenomenon. In scenarios where chemosis is undesirable, a high-volume deeply placed retrobulbar block may be inappropriate.
Competing Interests
The authors declare no competing interests.
References
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Luyet, C, Eng, KT, Kertes, PJ, Avila, A, Muni, RH, McHardy, P Real-time evaluation of diffusion of the local anesthetic solution during peribulbar block using ultrasound imaging and clinical correlates of diffusion.. Reg Anesth. (2012). 37 455–9 [Article]