LET gel-induced pharmacological anisocoria in a pediatric patient: A case report

LET gel, composed of lidocaine (4%), epinephrine (1:2000), and tetracaine (0.5%), is a commonly used topical anesthetic agent in various dermatological procedures. It provides effective local anesthesia and vasoconstriction, making it ideal for wound closure. It gained popularity in the mid-nineties, replacing TAC (tetracaine, adrenaline, and cocaine) due to its comparable efficacy, cost-effectiveness, and non-controlled drug ingredients. While LET gel has a good safety profile, it is essential for healthcare professionals, especially emergency physicians, to be aware of potential untoward events associated with its use. One of the potential side effects of its use is pupillary dilation, or mydriasis, if the gel seeps into the eyes during application. All three components of the gel are mydriatic agents. Epinephrine acts on both α- and β-receptors. It induces pupillary dilation through α-receptors-mediated sympathetic activation of dilator pupillae as well as parasympathetic activation of the sphincter pupillae by acting on β-receptors. Lidocaine and tetracaine, on the other hand, block sodium channels and block both sympathetic and parasympathetic pathways, resulting in mydriasis. As pupillary size is primarily determined by the parasympathetic supply to the sphincter pupillae, the net effect of these agents is dilation. It is important to note that lidocaine and tetracaine can also cause a loss of pupillary reflexes, which is not influenced by epinephrine. Proper technique and caution should be exercised during the application of LET gel, especially around the eyes, to minimize the risk of ocular complications. Conservative management and observation are recommended in cases without red flags of head injury to avoid unnecessary radiation exposure.

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Published in: Visual Journal of Emergency Medicine
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.visj.2023.101786