Medial canthus episclera (sub-Tenon's) anaesthesia is a technique proposed as a suitable alternative to the more classical peribulbar block because of the greater reliability and more constancy in effectiveness. We report two cases of retrobulbar haematoma after sub-Tenon's anaesthesia, one with central retina artery compression needed anterior room punction. Sub-Tenon's anaesthesia, like peribulbar anaesthesia, can give also retrobulbar haemorrhage if the insertion of the needle is not limited to the anterior orbit.