Staggered sub-Tenon's blocks: a novel anesthetic approach for bilateral strabismus surgery.

Bilateral strabismus surgery is usually performed under general anesthesia. However, sometimes general anesthesia is not in the best interest of patients presenting with advanced multiple comorbidities. These patients are best treated with local anesthesia instead. However, the bilateral nature of the surgery becomes an issue because bilateral akinetic needle blocks for ophthalmic surgery have not been described before. This article describes a novel approach for bilateral eye surgery in three patients who were at high risk from general anesthesia but needed to have the surgery performed in the same sitting. Staggered blunt needle sub-Tenon's blocks were chosen over sharp needle akinetic extraconal peribulbar or intraconal retrobulbar blocks on account of their predictability, relative safety, and efficacy. The potential systemic complications of bilateral injections were minimized by staggering the blocks. This technique may be an option for high-risk patients who are not candidates for general anesthesia but require bilateral ophthalmic surgery performed in a single surgical episode.

A review of directions of gaze during intraocular anesthetic blocks.

Safety of orbital blocks depends on operator and patient factors. Among the patient factors, the direction of gaze is important. Certain ocular structures move when the gaze is shifted. These may veer into the path of the needle, setting the stage for injury. The optic nerve with its accompanying artery swerves medially during abduction, direct up gaze, and superolateral and inferolateral gazes. These gazes are therefore risky for medial compartment blocks. In a superomedial gaze, the optic nerve shifts down and out and is likely to be injured during inferolateral needle blocks. Primary gaze is considered to be the safest for akinetic sharp needle blocks. "Tethering tests" involving extremes of gazes are dangerous. The superomedial, superior, superolateral, and inferomedial routes are perilous in all gazes. The superolateral gaze during classic Steven's sub-Tenon's block brings the optic nerve forward, rendering it vulnerable. Complications can be reduced by avoiding deep blind dissection and posterior injections.

Sub-tenon's block: a national United Kingdom survey.

BACKGROUND AND OBJECTIVE: A survey was undertaken to ascertain current practices in ophthalmic regional anesthesia with an emphasis on sub-Tenon's block. Despite its increasing use, there are currently no guidelines for its explicit management. PATIENTS AND METHODS: An anonymized postal questionnaire survey was sent to 173 consultant anesthesiologist members of the British Ophthalmic Anaesthesia Society. RESULTS: Sub-Tenon's blocks were regularly performed by 87.8% of respondents. The majority used a blunt metal cannula via the inferonasal quadrant. Local anesthetic was placed post-equatorially by 58% of respondents and deep posteriorly by 16.7%; 18% used vasopressors. There was no agreement for aseptic precautions, international normalized ratio, platelet levels, or venous access. Complications included vascular and muscular injuries, a case of fainting, and several cases of dysrhythmias. Current United Kingdom guidelines for monitoring patients were not being followed. CONCLUSION: These results show a need for robust national guidelines, especially in view of increasing use, indications, and potential risks of sub-Tenon's block.