Purpose of review: Needle-based and cannula-based eye blocks are 'blind' techniques prone to rare but serious complications. Ultrasound, an established adjunct for peripheral nerve block, may be beneficial for ophthalmic anesthesia application. The present review details the evolution of ultrasound-guided eye blocks, outlines safety issues, and reviews recent studies and editorial opinions.
Recent findings: Ultrasound-assisted ophthalmic regional anesthesia allows imaging of key structures such as the globe, orbit, and optic nerve. Recent findings reveal that needle path is not reliably predictable by clinical evaluation. Needle tips are frequently found to be intraconal, extraconal, or transfixed in the muscle cone independent of the intended type of block. In addition, contemporary human and animal studies confirm that real-time observation of local anesthetic spread inside of the muscle cone correlates directly with block success.
Summary: Ultrasound-guided ophthalmic regional anesthesia is evolving beyond simple visualization of the anatomy. Recent research emphasizes the imprecision of needle tip location without ultrasound and the key role of imaging local anesthetic dispersion. There is ongoing debate in the literature regarding the utility of routine ultrasound for eye blocks.