Ocular anaesthesia

Chairperson:DR. RUBINA YASMIN

ASSOCIATE PROFESSORDEPT. OF ANAESTHESIOLOGY

NIO&H Moderator:

DR. KANIJUN NAHAR QUADIRASSISTANT PROFESSOR

DEPT. OF ANAESTHESIOLOGYNIO&H

Presenter:DR. NAFIZ MAHMOOD

DO STUDENTNIO&H

OCULAR ANAESTHESIA

ANAESTHESIA:

Reversible loss of feeling or sensation, specially the

loss of pain sensation induced to permit to

performance of surgery or other painful procedures.

From the page of History

Born: December 3, 1857

Died: March 21, 1944

Nationality: AustriaFields: Ophthalmology

Known for:

Cocaine (a south american bush ERYTROXYLUM COCA.)as a local anaesthetic in 1884Ophthalmic surgeon work in Vienna

Karl Koller

From the page of History

Born: March 17, 1832

Died: April 30, 1911

Hermann Jakob Knapp

In 1884 used cocaine for retrobulbar block.

van Lint achieved orbicularis akinesia by local injection

From the page of History

General anaesthesia:First used by W.T.G Morton of Boston, USUsed – ETHER at Massachusetts General Hospital on 16th October 1846 to Gilbert Abbott

Types of ocular anaesthesia : General anaesthesia Local anaesthesia

Topical Regional

Peribulbar blockRetrofbulbar blockParabulbar or sub-tenon blockIntracameral blockFacial blockFrontal block

PREFERRED ANAESHETIC TECHNIQUELOCAL ANAESTHESIA:

• Pterygium • Cataract• Surgery for glaucoma• Minor extra-ocular plastic surgery• Keratoplasty • Dacryocystorhinostomy• Minor anterior segment procedures• Refractive surgey • Vitreo-retinal surgery etc

GENERAL ANAESTHESIA:

• Paediatric surgery• Sqint surgery• Major oculoplastic surgery• Orbital trauma repair• Dacryocystorhinostomy• Vitreo-retinal surgery

GENERAL ANAESTHESIAFOR OCULAR SURGERY

INDICATION:1. In children and infant2. Anxious & uncooperative patient3. Mentally retarded adult4. Patient’s preference

OBJECTIVE:5. Analgesia6. Amnesia7. Loss of consciousness8. Adequate skeletal muscle relaxation

Advantages:

I. safe operative environment

II. Complete akinesia

III. Controlled intra-ocular pressure

IV. For bi-lateral surgery

V. Avoiding complications of L/A

PRE- ANAESTHETIC CHECKUPGENERAL:

• Nutritional status• Retarded growth• Anaemia• Jaundice• Cough• Temperature• Oedema• History of convulsion

RESPIRATORY SYSTEM :

• Cyanosis • Dyspnoea• Auscultation of lung field

AIRWAY:

• Mouth opening• Neck movement• Dentition

CARDIOVASCULAR SYSTEM :• Pulse • Blood pressure• Heart sound (auscultation)• Dependent oedema

INVESTIGATIONSFull blood countUrine analysisStool R/EChest X-ray

Over 40 yearsBlood glucoseECGBlood urea S.Creatinine

OTHER INVESTIGATIONS: S. electrolytes Liver function test Coagulation screening

Echocardiogram – specially for congenital heart disease(valvular disease) also for adult – if indicated

Procedure of General Anaesthesia

1) Pre-medication for anaesthesia

2) Induction & intubation

3) Maintenance & Monitoring

4) Extubation and Recovery

Drugs used in G/A1. Pre-medication for anaesthesia with

• Benzodiazepines (diazepam) –for sedation and reduce

anxiety

• Anti-emetics – metaclorpramide , ondansetron

• Atropine - prevent bradycardia

reduce bronchial and salivary secretion

• Medication for selective patients - hypertensive ,

diabetic , coronary artery disease

2.InductionThiopentone ( thiopental sodium) – 5 mg/kgPropofol – 2.5 mg/kg

3. Maintenance• Muscle relaxants – suxamethonium, vecuronium

etc

• anaesthetic gas – nitrous oxide (N2O) with O2

and Halothene , isoflurane etc.

4. Recovery• Neostigmine • Atropine

• Intravenous agent – pethidine , Fentanyl , NSAID(for pain reduction)

COMPLICATION of G/A• Hypoxia

• Laryngospasm

• Respiratory depression

• Aspiration pneumonitis

• Cardiac arrythmia

• Hypotension / Hypertension

• Convulsion

• Restlessness

EFFECTS OF ANAESTHETIC AGENTS ON IOP

DRUGS EFFECT ON IOP

INHALED ANAESTHETICSVolatile agentsNitrous oxide

Intravenous agentsBarbituratesBenzodiazepinesKetamineOpioids

MUSCLE RELAXENTDepolarizers (succinylcholine)Non- depolarizers

LOCAL ANAESTHESIA

ADVANTAGES: Patient is conscious and alert

Drugs used in G/A can be avoided

Systemic complication is less – Post-operative confusion

Nausea , Vomiting

Urinary retention

Stress response to

cardiac patient

acts by producing reversible block to the transmission of peripheral nerve impulses

DISADVANTAGES:

• Painful

• Difficult in uncooperative patients

NOT SUITABLE FOR:

• Young patient• Mentally unstable patient• Patient with physical disabilities that prevent lying

DESIRED PROPERTIES OF L/A1. Non-irritating , safe and painless2. Must be water soluable3. Rapid onset of action4. Duration of action appropriate to the operation to be

performed5. Non-toxic6. No local after effects ( nerve damage , necrosis)7. Must be effective regardless its application to tissue or

mucous membrane8. Quickly block motor and sensory nerves

LOCAL ANAESTHESIA

Na chann

el

LAH+ (ionised drug)

LA(free base)

LA(free base) LAH+

(ionised drug)

NERVE AXON MEMBRANE

ACTION OF LA

MECHANISM OF ACTION OF L/A

Binds with protein of Na+ channels (at interior side)

Block voltage dependent Na+ conductance ( prevent Na+ influx)

Block depolarization

Initiation and propagation of action potential fails

Afferent impulses can not go to higher center

No pain sensation

Patient preparation for LA

As for GA

Optimal health condition

Friendly rapport

A suitable vein should always be cannulated in all

patient

Full cardio-pulmonary resuscitation equipment

Appropriate monitoring

Toxicity of LA:• Light headedness• Numbness or tingling of circumoral area• Anxious• Drowsy• Tinnitus • Convulsion ( To prevent- Diazepam or TPS)• Coma & apnoea develop subsequently (O2)• Cardiovascular collapse may result due to myocardial depression & vasodilatation

HYPOXAEMIA APNOEA

Types of LA According to chemical structure

Ester group Amide groupProcaineCocaineTetracainebenzocaine

LidocaineBupivacaineRopivacaine

mepivacaine

Esters may cause more allergies

COMMONLY USED L/A

L/A Onset of action

Duration of action

Use (concentratio

n)Oxybuprocai

ne6-20 sec 15 min Topical

(0.4%)

Lignocaine

5-10 min

10- 35 sec

30-60 min

15-20 min

Infiltration (1%,2%,4%)

Topical (4%)

Bupivacaine Moderate 75-90 min Infiltration (0.25-0.75%)

OTHERS

L/A Onset of action

Duration of action

Use (concentratio

n)

Proparacaine

15-30 sec 15-20 min Topical (0.5%)

Amethocaine

10-25 sec 10-20 min Topical (0.5-1%)

Ropivacaine Moderate 1.5-6hrs Infiltration (1%)

TOPICAL ANAESTHESIA

ADVANTAGES: Cost effective Immediate visual recovery Avoidance of complication - globe rupture , nerve

damageDISADVANTAGES:

No akinesia Not suitable for extended surgery Well informed and motivated patient is required

ADVERSE EFFECT OF TOPICAL ANAESTHESIA

• Epithelial and Endothelial toxicity

• Allergy to drug

• Alteration of lacrimation

• Surface keratopathy

USES OF TOPICAL ANAESTHESIA

• Manipulation of superficial cornea and

conjunctiva

• Phacoemulsification in cooperative

patient

• Prior to regional blocks

PERIBULBAR BLOCKMost popular now a days

AIM:Injected into peribulbar spaceSpreads to lid and other spacesProduces globe and orbicularis akinesia and anaesthesia.

L/A agent :o Lignocaine 2%o Bupivacaine 0.75%

Along witho Hyaluronidase 5-7.5 IU/mlo Adranaline 1: 200,000

VOLUME :

8-10 ml (approximately)

INSERTION POINT:• 1st - Junction of medial 2/3rd and lateral 1/3rd of lower

lid adjacent & Parallel to orbital floor • 2nd - Just infero-medial to supra orbital notch or just

medial to medial canthus

POSITION OF PATIENT: Supine and in primary gaze

USE OF PERIBULBAR BLOCK

1. Cataract

2. Glaucoma

3. Keratoplasty

4. Vitreoretinal surgery

5. Strabismus surgery

ADVANTAGES:• Less chance of globe injury• Less chance of optic nerve damage

DISADVANTAGES:• Pain• Conjunctival chemosis• Less akinesia than retrobulbar block

RETROBULBAR BLOCKAIM: Injected in muscle cone to block

• Cilliar nerve and ganglion• 3rd , 4th & 6th cranial nerves • provides - akinesia and anaesthesia of the globe.

POSITION OF PATIENT: Supine and in primary gaze

SITE OF INJECTION:

In the lower lid margin just above a point between medial 2/3rd & lateral 1/3rd of lower orbital margin

DIRECTION OF NEEDLE: backward , upwards and medially towards apex of orbit

VOLUME: 2 – 4 ml usually

ADVANTAGES:• Complete akinesia• Dilatation of pupil• Adequate and quicker anaesthesia• Minimal amount of agent required

Complications :

Retrobulbar haemorrhage

Globe penetration

Optic nerve sheath injury

Optic nerve atrophy

Decrease visual acuity

Retinal vascular occlusion

Cont… Brain stem anaesthesia

Frank convulsion

Extra ocular muscle palsy

Trigeminal nerve block

Oculo-cardiac reflex

Respiratory arrest

Contraindication :

• Bleeding disorder ( risk of retrobulbar haemorrhage)

• Extreme myopia ( globe perforation)

• An open eye injury (may cause expulsion of intraocular

contents)

• Posterior staphyloma

PARABULBAR OR SUB-TENON BLOCK

Conjunctival incision 2-3 mm

Halfway between inf. limbus & fornixto open sub-tenon space

Blunt canulla or needle is inserted to post. Sub-tenon space

Bathing the nerves & muscles within the cone

DRUG : LIGNOCAINE

Dissection

Infiltration

ADVANTAGES:• Avoid vascular and optic nerve injury• Requires lower volume of anaesthetics• Better anaesthesia to iris and ant.segment

DISADVANTAGES:• Subconjunctival haemorrhage• More post-operative morbidity

FRONTAL BLOCKAIM: to block supra-orbital and supra-trochlear nerve supplying the upper lid.

USE: ptosis surgery

SITE OF INSERTION: just below mid-point of supra- orbital margin transcutaneously directed towards roof of orbit

VOLUME: about 2 mlw

INTRACAMERAL ANAESTHESIA

AGENT: lignocain 1% (without preservative or adrenaline)

USE: used for phacoemulsification

FACIAL BLOCK

AIM: blocking the action of orbicularis oculi.

USE : as an adjunct to retrobulbar block.

TYPES:

1. Van lint2. O’Brien3. Nadbath & Rehman4. Atkinson

Major sight and life-threatening complications

A. Retrobulbar orbital haemorrhage

SIGNS & SYMPTOMS

• rapid intraorbital and intraocular pressure elevation• increasing proptosis•marked pain• ecchymoses in the eyelids • Chemosis• vision down to poor perception or no perception of light

MANAGEMENT:

Evaluation: Indirect ophthalmoscopy - for evidence of central retinal artery perfusion compromise.

Immediate medical treatment:intravenous osmotic agents such as – • acetazolamide • mannitol

Surgery: Surgical decompression such as -

• Canthotomy,

• Cantholysis

• Orbital decompression

B. Globe perforation: (Exceptionally soft eye ; myopic eye is more prone)

• Occurred with retrobulbar and peribulbar anaesthesia• suspected if – marked pain during the delivery of local an aesthesia hypotony with inability to secure a stable globe -

intraoperative signs of perforation reduced red reflex due to vitreous haemorrhage Serious sight threatening vitreoretinal complications may

result

**** seek the advice of a specialist vitreoretinal surgeon

C. Nerve InjuryOptic nerve may be damaged by:

●● direct trauma by needle

●● ischaemic damage from intrasheath injection or

haemorrhage

●● pressure from retrobulbar haemorrhage

●● pressure from excess local anaesthetic injection into

the retrobulbar space

●● excessive applied external pressure.

NEED TO CARE :• avoiding deep injections into the orbit and• injecting with the eye in the primary position

D. Brain stem anaesthesiaDue to spread of local anaesthetic along the optic nerve sheath

SYMPTOMS & SIGNS:

• drowsiness

• light-headedness

• confusion

• loss of verbal contact

• cranial nerve palsies • convulsions • respiratory depression or respiratory arrest • cardiac arrest

ONSET OF SYMPTOMS: within 10-20 mins of LA injectionSYMPTOMS LASTS FOR: Hours

E. Muscle palsy

Diplopia and ptosis are common for 24–48 hours post-operatively when large volumes of long-acting local anaesthetics are used.

If this persists or fails to recover, it may be due to muscle damage as a result of :

• intramuscular injection of local anaesthetics• local anaesthetic myotoxicity• ischaemic contracture following haemorrhage/trauma

F. Oculocardiac Reflex (Trigeminovagal reflex)

Trigeminal nerve – afferent and vagal efferent pathway

CAUSES:

• Traction on extra-ocular muscle• Pressure on globe

RESULT: Bradycardia Ventricular ectopy Ventricular fibrilation

AFFERENT PATHWAYImpulses

Long & short cilliary nerve

Cilliary ganglion

Trigeminal gasserian ganglion

main trigeminal sensory nucleusin the floor of the 4th ventricle

EFFERENT PATHWAYCardiovascular center of medulla

Vagus nerve

Heart

LCN

SCN

CG TGG

VN

afferent

efferent

Treatment • Stop the surgical stimulus immediately. • Ensure adequate ventilation . • Ensure sufficient anesthetic depth.

Atropine / Glycopyrrolate (anti-cholinergic): often helpful immediately or prior surgery

TAKE HOME MESSAGES• All local anaesthetic agents are myotoxic• Direct injection into a muscle should be avoided• No LA technique is entirely free of severe systemic adverse events• short, fine needle should be used• the eye in the primary gaze position (looking straight ahead)• Gentle aspiration after insertion of needle should be done to alleviate possible entry to blood vessel.• Bevel of the needle facing the globe and tangenital to sclera.• All occular surgery with LA should be treated as GA.