1. SUB-TENON’S ANAESTHESIA

2. Ocular Anaesthesia Retrobulbar (intraconal) Peribulbar (extraconal)
Topical
Sub-conjunctival
Sub-Tenon’s

3. Use of “sharp instruments” in the peribulbar and retrobulbar anaesthesia has been quoted as causing possible serious and even vision threatening complications
globe perforation
orbital haemorrhage
optic nerve damage
subarachnoid diffusion

4. A relative new and safer technique Sub-Tenon block

5. Sub-Tenon’s Space
Tenon´s capsule: thin layer of connective tissue which surrounds the globe.
Anteriorly it lies in close apposition to the conjunctiva and fuses with it at the level of the limbus.
Posteriorly surrounds the globe and fuses with the dura of the optic nerve

6. Anatomy of Sub-Tenon’s Space

7. The sub-Tenon´s space is a virtual space between the capsule and the sclera.
The instillation of local anaesthetic into this space produces analgesia and akinesia by diffusing posteriorly into the retro-orbital space to block the traversing sensory and motor nerves.

9. Contraindications (Relative)
Large vascular nasal pterygium
Recent pterygium surgery (with graft)
Scleral buckle surgery
Previous or planned Glaucoma Drainage implants
Previous or planned Trabeculectomy
Ocular Cicatricial Pemphigoid
Steven-Johnson’s syndrome

10. Sub-Tenon Cannula

11. Procedure

12. Complications Minor Slight pain Overspill of anaesthetic Chemosis
Conjunctival haemorrhage

13. Complications Significant Diplopia Orbital or Retrobulbar haemorrhage
Scleral perforation
Optic neuropathy, choroidal and retinal vascular occlusion (rare)
Cardiorespiratory collapse

14. Conclusion Reliable and low risk profile anaesthetic technique
Highly suitable for day care surgical settings
Largely accepted by both the surgeons and anaesthetists