| Inadvertent subarachnoid anaesthesia (Brain–stem anaesthesia) |
Subject to debate but spread through optic nerve sheath or through the orbital foramina |
Placement of long needle into the apex |
0.3–0.8% (retrobulbar)
Unknown (peribulbar) |
Avoid using long needle |
Extensive cardiorespiratory support |
| Ocular perforation |
Direct needle entry into the globe through sclera |
Placement of needle angled towards the apex |
3 : 4000 (retrobulbar block)
1 : 16 224 (peribulbar block) |
Attention to anatomy and appropriate technique |
Immediate ophthalmic opinion |
| Retrobulbar haemorrhage |
Damage to arterial or venous blood vessels behind the globe |
Elderly receiving, steroids, NSAID, aspirin |
0.1–3% |
Limit insertion of needle <31 mm in the relatively avascular area |
Immediate oculocompression, ophthalmic opinion and decompression surgery if necessary |
| Globe ischaemia |
Interruption of blood flow |
Prolonged oculocompression |
Unknown |
Use pressure limiting oculocompression device |
Ophthalmic opinion |
| Optic nerve atrophy |
Direct damage to nerve, central retinal artery, or secondary to haemorrhage |
|
Unknown |
Careful needle placement |
Ophthalmic opinion |
| Damage to the motor nerve of the inferior rectus and inferior oblique muscles |
Direct trauma to the nerve |
Insertion of needle at the junction of medial 2/3rd and lateral 1/3rd of inferior orbital margin |
Unknown |
Careful needle placement avoiding the nerve |
Ophthalmic opinion |
| Prolonged extraocular muscle malfunction |
Prolonged exposure of fine muscle fibres, injection of local anaesthetic agent into the muscle |
May be associated with non-use of hyaluronidase |
Unknown |
Proper placement of needle |
Ophthalmic opinion |
| Orbital swelling |
Infection
Excessive dose of hyaluronidase |
Poor technique |
Unknown |
Aseptic technique
Use of recommended dose of hyaluronidase |
Antibiotics, steroids ophthalmic opinion |
