Abstract
BACKGROUND: Retrobulbar hemorrhage is a rare, sight-threatening complication from trauma, orbital surgery, and, rarely, regional orbital anesthetic injections. This may lead to orbital compartment syndrome with vascular and neural compromise and subsequent irreversible vision loss if not addressed promptly. Retrobulbar hemorrhage following sub-Tenon's anesthetic is very rare, typically occurring in patients with an increased risk of bleeding from various causes. CASE PRESENTATION: A 75-year-old Asian male with no known bleeding diathesis developed an acute retrobulbar hemorrhage immediately following a routine sub-Tenon's block performed for a planned encysted bleb needling. The patient experienced sudden onset of severe ocular pain with tense eyelids, loss of extraocular movements, and ocular hypertension. Emergency lateral canthotomy and cantholysis resulted in prompt resolution of orbital compartment syndrome. CONCLUSION: This case highlights a rare occurrence of retrobulbar hemorrhage following a routine sub-Tenon's block in a patient without predisposing risk factors. Prompt recognition and timely intervention were crucial in preserving the patient's vision. The case underscores the importance of vigilance and awareness of retrobulbar hemorrhage as a potential complication of sub-Tenon's block.