Ophthal

Question 2

What local anaesthetic solution do you use for performing your eye blocks and why?

SS_OP 1.4

Answer 2

1. 2% lignocaine 2mL
2. 1% Ropi / 0.5% Bupi 2mL
3. Hyaluronidase 150 iu

Hyal 75iu/mL

2% lidocaine: 5–10mL provides up to 90min of anaesthesia.
* 0.5–0.75% bupivacaine—may be used in combination with
lidocaine to prolong the block.

Hyal
1. Improve the spread of the block
2. Reduce proptosis by reducing
loculation of LA.

Question 3

What are the anaesthetic issues with regard to strabismus surgery and how are these managed?

SS_OP 1.8

Answer 3

Issues
1. Paeds - often
2. OCR
3. Requires neutral gaze
4. Limited access to AW
5. PONV
6. Opioid use - postop apnoea

Paeds - congenital/metabolic/prematurity

OCR prophylaxis
1. LA block - subt and PB - block CILIARY AFFERENT nerves
2. Avoid hyperCO2

Tx
1. Stop traction
2. Vagolytic
- Glyco 200-400mcg / atro 300-600mcg

Question 4

What are the anaesthetic issues with regard to penetrating eye injury?

SS_OP 1.9

Answer 4

AIM - NO COUGH

Paeds -
1. Unfasted
2. Anti-emetic

Sux - IOP up for 10 mins
Intubation with SA opioid

mRSI
1. dose of propofol at the upper end of its dose range,
2. a non-depolarizing relaxant,
3. gentle ventilation during cricoid pressure with high concentration of volatile agent while
4. taking care that the face mask is not pressing against the eye.

Sims P.425
Oxford Anaes P.815

Question 5

What methods do you know of to reduce intraocular pressure as part of an eye block? What are the risks involved?

SS_OP 1.12

Answer 5

1. Hyaluronidase
2. Minimise LA volume

Other ways to red IOP
1. Head up GA relaxant
2. Avoid eye compression
3. Hypervent (Dec CO2)
4. IV acetazolamide 500mg (dec aqueous production) and mannitol 0.5mg/kg (inc vitreous drainage)

IOP
1. aqueous humour
- increased drainage - pilocarpine
- reduce production - timolol
- choroidal blood
- sBP 80-90
3. Vitreous
- mannitol
4. Iatrogenic
- SF6/C3F8

Oxf AT P. 535

Question 5

What are the relative risks and benefits of peribulbar versus subtenon anaesthesia for eye surgery?

What is the incidence of globe perforation with peribulbar and sub-tenon techniques and how may the risk be minimised?

What are the features of brainstem anaesthesia and how are they managed?

SS_OP 1.11

Answer 5

Peribulbar
1. Good quality anaes
2.

Risk:
1. Retrobulbar haem
2. Globe perf
3. Optic nerve damage

Axial length > 26mm = subtenon

Globe penetration %
PB: 1:12k-16k
Subtenon: Very rare

1. Avoid medial compartment injection
2. Use fine short needle (25G <25mm)
3. Check INR

Question 6

In the pre-operative assessment for a patient undergoing eye surgery under local anaesthesia, what are the important issues?

SS_OP 1.13

Answer 6

4A

• Anticoagulation status
• INR/APTT - no PB
• Ability to lie flat
• Ability to cooperate
• Axial length of the globe >26mm - preclude PB

Question 7

What is your method of sedation for eye procedures? What are the risks involved?

SS_OP 1.15

Answer 7

Pt selection

IV/O2/monitoring/CO2

Midazolam bolus 0.5mg - 2mg- risk of POND

Block insertion
1. LD Props - 10-30mg
2. Fent / alf - 25-50mcg / 100-200microg

Reassure / regain full cooperation before surgery

Plan to convert to GA

Ox Ana P.810

Question 8

What are the patient and staff issues involved when performing laser procedures in eye surgery

SS_OP 1.17