3.20 Sub-Tenon's Eye Block Flashcards
List advantages
RA eye surgery
- More suitable for DOSA
- Avoid complications GA
- Comorbs/sore throat/ PONV - Post op analgesia
- Faster turnover
- Analgesia + Akinesia
- Blunting occulo-cardiac Reflex
Disadvantages
RA eye surgery
- Chronic cough poorly tolerated
- Patient unable lie flat
- anticoagulation
INR >2.5 - Prev retinal detach = contraindication
- Trauma to eye
- Local infection
- Poor for long surgery
Subtenon’s block - why good
Ideal eye block:
Anaesthesia + Akinesia = optimal surgical conditions
without risk of retro and peribulbar tech
SLIMRAG
Technique
dissect down to tenons capsule
- fascial layer of CT surrounds glove and extra ocular muscles
(axial length checked - >26mm increased risk globe perf)
Technique
Conjunctival block -
Topical LA eye drops
Iodine drops inserted also
Eyelid retractor
Patient look up and outward
Inferonasal quadran
lift small tent conjunctiva w/ forceps
:midpoint between medial limbus and med canthus
Small incision thru conjunctiva - ophthalmic scissors
Blunt dissection down thru Tenon’s fascta to sclear
Technique
Blunt Tenons cannula (19g) inserted with tip against sclera
Navigated posteriorly - minimal resistance
Resistance d/t incorrect tissue plane dissection
solve with redirection of cannula
Occas - fibrous band @ equator
correlating w/ insertion of exoccular muscle
gentle pressure overcomes
Aspirate + inject LA
Mild proptosis of globe = correct spread of block
Some anterior spread normal
excess chemosis = sunconjucnt spread
= analgesia but not akinesia
Remove cannula
Gentle massage glove = aid retrograde spread LA solution
some prefer pressure device
Complications block
Needle
Low - blunt needle
- Dural puncture / Subarachnoid injection
- Vascular injury + retrobulbar haemorrhage
avoid superomedial quadrant - Scleral perf
- Subconjunctival haemorrhage + chemosis
- Muscle injury
Complications block
Related to LA
- Subarachnoid injection + spread of LA
- Intravascular injection
- Anaphylaxis
- Diplopia
- Raised IOP
