Regional Anesthesia for Ophthalmic Surgery

The Sub-Tenon Block

Abstract

Sub-Tenon’s block is a regional anesthetic technique widely used in ophthalmic surgery as a safer alternative to retrobulbar and peribulbar blocks. The technique involves injecting local anesthetic into the sub-Tenon’s space using a blunt cannula after a small incision is made in the conjunctiva and Tenon’s capsule. A thorough understanding of orbital anatomy, conjunctiva, Tenon’s capsule, vascular supply, and innervation of the eye is essential for the success of this block. Various local anesthetics can be used, either alone or in combination, with adjuvants such as hyaluronidase to enhance diffusion and improve block quality. Sub-Tenon’s block provides reliable analgesia with generally adequate akinesia for cataract, vitreoretinal, and other ophthalmic procedures, while carrying a relatively low risk of complications. Other advantages include greater patient comfort and suitability for high-risk groups where needle blocks are contraindicated, such as patients with high myopia or those receiving anticoagulant therapy. Nevertheless, limitations such as incomplete akinesia, particularly of the superior oblique muscle, and the occurrence of chemosis or subconjunctival hemorrhage should be anticipated. With strict aseptic technique, appropriate anesthetic volume, and skilled providers, Sub-Tenon’s block remains an effective, safe, and relevant option in modern ophthalmic anesthesia practice