Anterior Sub-Tenons Anaesthesia (ASTA) For Cataract Surgery

1. Kong Chan Tang^1,2
2. Donna Tomkins²
3. Sharnie Wu¹

¹Lithgow Hospital, Lithgow NSW, Australia
²MidWest Ophthalmology, Orange NSW , Australia

Purpose: Retrobulbar and peribulbar anaesthesia are effective in providing analgesia and akinesia during cataract surgery. However there are associated risks of retrobulbar haemorrhage and globe perforation. Sub-Tenons anaesthesia partly alleviates some of these risks but require more instrumentation. Topical, subconjunctival and intracameral anaesthesia do not provide any akinesia.

We wish to describe and illustrate the method of Anterior Sub-Tenons Anaesthesia(ASTA) using a single injection into the anterior sub Tenons space which provides analgesia and akinesia similar to a traditional sub-Tenons block, but with less instrumentation.

Method: 2 groups of 30 cataract patients were given ASTA using either Lignocaine 2% or Lignocaine 2%/Bupivicaine 0.5% injections in a random order . A volume between 5 to 10 ml of anaesthetic containing 30iu/ml of Hyaluronidase is injected into the anterior sub-Tenons space using a short 25 G needle. The block is assessed on the degree of eye movement, ptosis, amaurosis and pain during surgery and with Gentamicin/Celestone injection at the end.

Results: Analgesia and akinesia scores are comparable to conventional sub-Tenons blocks. A video of this technique is shown.

Conclusion: ASTA is a promising technique requiring less instrumentation than conventional sub-Tenons blocks while providing similar operating conditions for cataract surgery.