Eye surgeryEye surgeryRequirements for eye surgery:Requirements for eye surgery:

1.1.Akinesia of the eyeAkinesia of the eye

2.2.Intense analgesiaIntense analgesia

3.3.Minimal bleeding (avoid HT or movement of eye)Minimal bleeding (avoid HT or movement of eye)

4.4.Management of oculo-cardiac reflexManagement of oculo-cardiac reflex

5.5.Control of intra-ocular pressure (IOP)Control of intra-ocular pressure (IOP)

6.6.Beware of drug interactionsBeware of drug interactions

7.7.Smooth recovery with no PONVSmooth recovery with no PONV

Oculo-cardiac reflexOculo-cardiac reflex• Occurs with pulling of eye muscles/pressure on eye ballOccurs with pulling of eye muscles/pressure on eye ball

• Afferent = N V (V1), efferent = N X → bradycardiaAfferent = N V (V1), efferent = N X → bradycardia

• Most common in children for strabismus repair, but can Most common in children for strabismus repair, but can occur during any ophthalmic procedureoccur during any ophthalmic procedure

• Management:Management:

1. Ask surgeon to stop pulling on muscles1. Ask surgeon to stop pulling on muscles

2. Confirm adequate depth of anaesthesia2. Confirm adequate depth of anaesthesia

3. Administer atropine (0.02 mg/kg) if bradycardia 3. Administer atropine (0.02 mg/kg) if bradycardia persistspersists

4. The reflex eventually fatigues itself with repeated 4. The reflex eventually fatigues itself with repeated pulling pulling

and release of eye musclesand release of eye muscles

Control of intra-ocular Control of intra-ocular pressurepressure

• Eye cavity = hollow sphere with a rigid wall. If contents Eye cavity = hollow sphere with a rigid wall. If contents ↑→ IOP ↑→ extrusion of ocular contents through open ↑→ IOP ↑→ extrusion of ocular contents through open surgical/trauma woundsurgical/trauma wound

• Anaesthesia can → ↑ IOP due toAnaesthesia can → ↑ IOP due to

1. laryngoscopy/ intubation (HT),1. laryngoscopy/ intubation (HT),

2. airway obstruction, coughing, ↑ CVP, 2. airway obstruction, coughing, ↑ CVP, Trendelenburg Trendelenburg

position (↓ venous drainage)position (↓ venous drainage)

3. ↑ PaCO2 (vasodilatation →↑ eye blood flow3. ↑ PaCO2 (vasodilatation →↑ eye blood flow

4. Drugs: Ketamine, suxamethonium →↑ IOP4. Drugs: Ketamine, suxamethonium →↑ IOP

• Other anaesthetic drugs (opioids, induction agents, Other anaesthetic drugs (opioids, induction agents, muscle relaxants do not ↑ IOP and are thus savemuscle relaxants do not ↑ IOP and are thus save

Drug interactionsDrug interactions

• Ecothiopate is a pseudocholinesterase (pCE) Ecothiopate is a pseudocholinesterase (pCE) inhibitor used to ↓ IOP but it can prolong the inhibitor used to ↓ IOP but it can prolong the action of suxamethonium (which is broken action of suxamethonium (which is broken down by pCE)down by pCE)

• Timolol is a Timolol is a ββ-blocker used in the eye to ↓ IOP -blocker used in the eye to ↓ IOP but can cause bradycardia, asthma etcbut can cause bradycardia, asthma etc

Strabismus surgeryStrabismus surgery

• Oculo-cardiac reflex = commonOculo-cardiac reflex = common

• ↑ ↑ incidence of malignant incidence of malignant hyperthermia (temperature hyperthermia (temperature monitoring = NB)monitoring = NB)

• ↑ ↑ incidence of PONV (consider incidence of PONV (consider prophylactic anti-emetics)prophylactic anti-emetics)

The open eyeThe open eye

• Emergency, thus can not wait for pt to be NPOEmergency, thus can not wait for pt to be NPO• Do rapid sequence induction (trauma delays Do rapid sequence induction (trauma delays

gastric emptying)gastric emptying)• Avoid Ketamine Avoid Ketamine • Consider suxamethonium (although ↑ IOP), Consider suxamethonium (although ↑ IOP),

because it is given with IV induction agent and because it is given with IV induction agent and opioid which both decrease IOP. opioid which both decrease IOP. Suxamethonium provide excellent intubation Suxamethonium provide excellent intubation conditions and thus prevents ↑ IOP due to conditions and thus prevents ↑ IOP due to coughing etc. coughing etc.

• Avoid all factors that ↑ IOP (see above)Avoid all factors that ↑ IOP (see above)