Ocular anaesthesia by dr.roopashree.c .r

RELEVANT ORBITAL ANATOMY
Orbit is a quadrilateral pyramid
Base directed forwards, laterally & slightly downwards.
Apex lies between optic foramen & medial end of
Superior orbital fissure.
Shortest orbital wall is floor approximately 47.6mm
(Depth from infra orbital rim to orbital foramen is 42 to
54mm )
Lateral wall makes an angle of 45
o
with median plane.
Orbital rim is usually 35mm vertically and 40 mm
horizontally in diameter.
Axial length of the eyeball is approx. 24mm.
Intraorbital length of optic nerve is 3.5 to 5.5cm.
Capacity of the eyeball is 30cc.

• Fig shows plane of Iris & midsagittal plane of the globe in
primary gaze (view from above).
• fine dash line-plane of Iris(useful in gauging depth of needle
advancement).
• coarse dash line-midsagittal plane of eye & visual axis
through the center of pupil
• .Optic nerve lies on the nasal side of midsagittal plane.
• Temporal orbital rim is set back from rest of the orbital rim
at or about the globe equator ,making for easy needle
access to the retrobulbar compartment.

SURGICAL SPACES IN THE ORBIT
 Knowledge of the main compartments of the orbit & their boundaries helps in choosing
the most direct approach to the tumor .
 As most orbital tumors tend to remain within the space in which they are formed unless
they are large ,malignant or infiltrative pseudotumor which spreads beyond.
 From surgical point of view ,orbit divided into 5 spaces :
1. Subperiosteal space
2. Peripheral Orbital space (Anterior space)
3. Central space
4. Sub - Tenon's space
5. Apical space

SUBPERIOSTEAL SPACE
o This is a potential space between orbital bones and the
periorbita.
o Limited anteriorly by the stong adhesions of periorbita to the
orbital rim.
o Dermoid cyst, epidermoid cyst, mucocele, subperiosteal
abscess, myeloma, osteomatous tumor, hematoma and fibrous
dysplasia are commonly seen in this space.
o Tumors arising from the bones separate periorbita from the
bones, which then becomes thicker & tougher, forming an
effective barrier against spread of tumor towards the eye,
unless subjected to extreme pressure for a long time.

PERIPHERAL ORBITAL SPACE (ANTERIOR SPACE)
• This space is bounded peripherally by periorbita, internally by
the four extra ocular muscles with their intermuscular septum,
anteriorly by the septum orbitale(including tarsal plates &
tarsal ligaments).
• Posteriorly, it merges with the central space.
• Contents :peripheral orbital fat, superior & inferior oblique
muscle,LPS ;lacrimal ,frontal,trochlear,anterior & posterior
ethmoidal nerves;superior & inferior ophthalmic veins;lacrimal
gland & half of lacrimal sac.
• Tumors present in this space produce eccentric proptosis and
can usually be palpated.
• Common tumors present in this space are malignant
lymphoma, capillary hemangioma of childhood,Rabdomyo-
sarcoma,neoplasms of the lacrimal gland,extension of nasal or
sinus diseases and pseudotumors.
• Tumors residing in this space are explored mostly by anterior
orbitotomy sometimes lateral orbitotomy.

CENTRAL SPACE
• Also called muscular cone or posterior or retrobulbar
space.
• Bounded anteriorly by tenon’s capsule lining back of
the eye & peripherally by extraocular rectus muscles
& their intermuscular septa(in anterior part)
• Contents of this space include optic nerve and its
meninges, superior and inferior divisions of
oculomotor nerve, abducent nerve, nasociliary nerve,
ciliary ganglion, ophthalmic artery, superior
ophthalmic vein and central orbital fat.
• Many of the circumscribed orbital tumors such as
cavernous hemangioma,AV malformations, solitary
neurofibroma, meningioma, optic nerve glioma occur
in this space and usually produce axial proptosis.
• Such tumors are often removed through a lateral
orbitotomy.

SUB - TENON'S SPACE
• It is a potential space around the eyeball between
the sclera and tenon’s capsule
• Pus collected in this space is drained by incision of
tenon’s capsule through the conjunctiva.
APICAL SPACE
It is bounded peripherally by periorbita; anteriorly
becoming continuous with the anterior space and
central space at the level of posterior limit of
intermuscular membrane & ending posteriorly at
the apex of orbit

TYPES OF OCULAR ANAESTHESIA
 General anaesthesia
 Local anaesthesia
 Topical
 Regional
1. Peribulbar block
2. Retrobulbar block
3. Parabulbar or sub-tenon block
4. Intracameral block
5. Facial block
6. Frontal block

PREFERRED ANAESHETIC TECHNIQUE
LOCAL ANAESTHESIA:
 Pterygium excision
 Cataract surgery
 Surgery for glaucoma
 Minor extraocular plastic surgery
 Keratoplasty
 Dacryocystorhinostomy/DCT
 Minor anterior segment procedures
 Refractive surgery
 Vitreo-retinal surgery etc

GENERAL ANAESTHESIA:
 Paediatric surgery
 Squint surgery
 Major oculoplastic surgery
 Orbital trauma repair
 Dacryocystorhinostomy
 Vitreo-retinal surgery

GENERAL ANAESTHESIA
INDICATION:
 Pediatric ocular surgery
 Mentally retarded & psychiatric patients
 Patients with painful arthritis, epilepsy or
frequent coughing
 Anxious, apprehensive patients
 Patient’s preference
ADVANTAGES:
 Safe operative environment
 Loss of consciousness & amnesia
 Complete akinesia ,analgesia
 Adequate skeletal muscle relaxation
 Controlled intraocular pressure
 For bilateral surgery
 Avoiding complications of L/A

PRE- ANAESTHETIC CHECKUP
DETAILED HISTORY AND GPE :
 History of convulsion & Cough
 History of HTN ,DM ,Asthma,CAD.
 Drug history
 Allergic history
 Nutritional status
 Retarded growth (Pediatric patients often have associated congenital
disorders (eg, rubella syndrome, Goldenhar’s
syndrome, Down syndrome).
 Anaemia ,Jaundice,Oedema,cyanosis
 Temperature
 Respiratory rate
 Pulse rate,Blood pressure

 Adequate Airway & Systemic Examination .
 Investigations :
Full blood count
Urine analysis
Chest X-ray
Blood glucose
ECG
Blood urea & serum creatinine
Echocardiogram – specially for congenital heart disease(valvular disease) also for adult – if indicated
Serum electrolytes
Liver function test
BT /CT
HIV & HbsAg

PROCEDURE OF GENERAL ANAESTHESIA
1) Pre-medication for anaesthesia
2) Induction & intubation
3) Maintenance & Monitoring
4) Extubation and Recovery

Pre-medication for anaesthesia:
• For sedation and reduce anxiety :intramuscular injection of combination of meperidine(pethidine) with
promethazine (phenergan). Alternatively, Benzodiazepines like diazepam 5 mg orally 2 hours preoperatively.
• Anti-emetics – metaclorpramide , ondansetron
• Atropine - prevent bradycardia, reduce bronchial and salivary secretion
• Medication for selective patients - hypertensive , diabetic , asthma , coronary artery disease
Induction:
• Thiopentone ( thiopental sodium) – 5 mg/kg onset is smooth and safe,and none of
• Propofol – 2.5 mg/kg them causes rise in IOP
• Ketamine –not suitable because of the high incidence of blepharospam, eyeball movements or hallucination
following its use in adults. Rise in IOP which is more sustained than transient rise, occurring during intubation
and following the use of suxamethonium.

• Halothane is most suitable since it offers rapid induction to sufficient depth, causes small fall in IOP, non
irritating to trachea.
• Low incidence of postoperative nausea and vomiting and acquire return of consciousness when the
anesthetic is withdrawn
Intubation:
• Suxamethonium (1-1.5 mg/kg body weight) intravenous: provides adequate condition for intubation (muscle
relaxation) and avoids coughing which causes rise of IOP.
• Endotracheal intubation and controlled ventilation.
Maintenance:
• Muscle relaxants – suxamethonium, vecuronium etc
• Anaesthetic gas – nitrous oxide (N2O) with O2 (33-66%) and Halothene(0.5-1.5%) , isoflurane etc.
• Intravenous agent – pethidine , Fentanyl , NSAID(for pain reduction)
• Intermittent positive pressure ventilation in order to achieve good hypotony.

Complication of GA:
• Hypoxia
• Laryngospasm
• Respiratory depression
• Aspiration pneumonitis
• Cardiac arrythmia
• Hypotension / Hypertension
• Convulsion
• Restlessness
Recovery:
Neostigmine (50 mg/kg)
Atropine (20 mg/kg)

EFFECTS OF ANAESTHETIC AGENTS ON IOP:
Normal
IOP 10-
21mmHg

LOCAL ANAESTHESIA
ADVANTAGES :
 Patient is conscious and will maintain mental alertness during surgical procedure
 Drugs used in G/A can be avoided
 Lowers risks of systemic complications: like nausea and vomiting
 Superior post-operative pain control and recovery time
 Early mobilisation
DISADVANTAGES :
 Painful
 Difficult in uncooperative patients
 Injection complications
 Not suitable for : children
Mentally unstable patient

DESIRED PROPERTIES OF LA :
 Transient loss of sensation and motor paralysis in specific area or body part.
 Non-toxic
 Non-irritating , safe and painless
 Rapid onset of action and duration of action appropriate to the operation to be
performed without local and systemic toxicity.
 Potency of local anesthetic agents is positively correlated with their lipid solubility,
as long as the water solubility is retained.
 No local after effects ( nerve damage , necrosis).
 Must be effective regardless its application to tissue or mucous membrane

ACTION OF LA :
LOCAL ANAESTHESIA
LAH+
(ionised drug)
LA
(free base)
acts by producing reversible block to the transmission of peripheral
nerve impulses
NERVE AXON MEMBRANE
LA
(free base) LAH+
(ionised drug)
Na
channel

MECHANISM OF ACTION OF L/A
Binds with protein of Na+ channels (at inner 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
 Detailed history & examination as for GA
 Optimal health condition
 Friendly rapport
 IV cannula
 Lignocaine test dose
 Full cardio-pulmonary resuscitation equipment
 Appropriate monitoring

LOCAL ANAESTHESIA
Types of LA :
According to chemical structure
Ester group Amide group
Procaine Lidocaine
Cocaine Bupivacaine
Tetracaine Ropivacaine
Benzocaine Mepivacaine
Esters may cause more allergies

COMMONLY USED LA :
Agents
(Trade name)
Chemical
classes
Concentration Max dose
(mg/kg)
Onset of
action
(min)
Duration of
action
Procaine (novocaine) Ester 1-4 % 12 7-8 30-45 min
Mepivacaine (Carbocaine) Amide 1-2 % 7 3-5 120 min
*Lidocaine (Xylocaine) Amide 1-2 % 7 4-5 40-60 min
*Bupivacaine (Marcaine,
sensocaine)
Amide 0.25-0.75 % 3 5-11 4-12 hrs
Etidocaine (Duranest) Amide 0.25-0.75 % 400 3-5 5-10 hrs
*Preferred regional anesthetic agent by most of the ophthalmic surgeons.
All commonly used topical anaesthetics are of ester type except lidocaine gel, while
All injectable anaesthetics are of amide type except procaine
The pKa of the local anesthetic solutions ranges from 8.00 – 9.00.

TOPICAL ANAESTHESIA
ADVANTAGES:
• Cost effective, Least invasive procedure
• Compression of eye is not required.
• Effect of anesthesia is immediate.
• Immediate visual recovery,
• Useful for monocular patients.
• Avoidance of :
 Postoperative ptosis
 Sight threatening complications (e.g. globe perforation,optic nerve damage)
DISADVANTAGES:
• No akinesia
• Not suitable for extended surgery
• Proficient experienced surgeons
• Well informed and motivated patient,
• Inability to handle intraoperative complications, if occurs,
• Unsuitability for anxious, deaf and those having dense cataract.

ADVERSE EFFECT OF TOPICAL ANAESTHESIA
 Epithelial and Endothelial toxicity.
 Allergy to drug: presents as conjunctival hyperemia,
chemosis, swelling of eyelids, lacrimation and itching.
 Tear film instability and reduced reflex tearing & thus
complicate the clinical picture in dry eye pateints.
 Surface keratopathy (diffuse punctate keratitis)

USES OF TOPICAL ANAESTHESIA :
o Manipulation of superficial cornea and conjunctiva
o Prior to regional blocks
o Diagnostic procedures like applanation tonometry & gonioscopy
o Removal of small superficial foreign body & suture removal
o Intraocular procedures like Phacoemulsification in cooperative
patient
o Specialised procedures like forced duction test
,electroretinography & corneal epithelial debridement.

TOPICAL ANAESTHESIA
 Several drops of 0.5 % cetakaine (Tetracaine) or 0.75 % bupivacaine or 4 % lidocaine
instilled at 5 to 10 minutes interval before surgery.
 2% Xylocaine gel into inferior fornix .
 Apply anesthetic to the eyelid margins using a soaked surgical spear.
 Use of preservative & adrenaline free intracameral lidocaine 1% in phacoemulsification.
 Masket’s technique of topical anesthesia includes use of 4 % lidocaine topical drops, 0.5
% tetracaine swab to limbus and 0.5 ml of 1 % nonpreserved lidocaine into anterior
chamber after paracentesis.
 Transient reduced but reversible contrast sensitivity and visual acuity were reported for
first few postoperative hours in those who received topical plus intracameral lidocaine.

REGIONAL ANAESTHESIA
LA agent :
o Lignocaine 2%
o Bupivacaine 0.75%
Along with
o Hyaluronidase 5-7.5 IU/ml
o Adrenaline 1: 200,000
Adrenaline :causes local vasoconstriction, thereby reducing the rate and extent of systemic
absorption of LA. This causes increased local availability of the local anesthetic agent and enhanced
neuronal uptake & thus increase duration of LA.
Dcreases blood loss during surgery.
Hyaluronidase : facilitate local spread of LA in the tissues.

RETROBULBAR BLOCK
AIM:
Injected in muscle cone to block
• Cilliary nerve and ganglion
• 3rd , 6th cranial nerves .
• provides - akinesia and anaesthesia of the globe.
POSITION OF PATIENT:
Supine and in primary gaze
SITE OF INJECTION:
The point between medial 2/3rd &
lateral 1/3rd of lower orbital margin.

DIRECTION OF NEEDLE:
• Backward , upwards and medially towards apex of orbit.
• Needle :25G, 1.5 inch(31mm) disposable blunt-tip retrobulbar needle (e.g., Atkinson
needle)
• Advance needle straight back ,parallel to orbital floor,perforating orbital septum.
• After septum is perforated and the equator of the
globe has been passed (~1 cm of needle
penetration/15 to 20 mm from skin surface),
direct needle superonasally at ~30 degree angle .
• Advance needle,piercing intermuscular septum
and enter muscle cone.

VOLUME:
 2 – 4 ml usually
 Gently move needle from side to side, looking for any movement of eye as a clue that the globe has been
penetrated.
 Aspirate syringe to ensure intravascular/intradural entry.
 After the injection intermittent firm digital pressure on the eye applied for 20 to 30 seconds and off for 5
to 10 seconds for 5 min duration, to prevent occlusion of the retinal circulation. It produces hypotony (
IOP), diffusion of anesthetic agent . May use Superpinkie or Honan balloon for 10 minutes.
ADVANTAGES:
 Complete akinesia
 Dilatation of pupil
 Adequate and quicker anaesthesia
 Minimal amount of anaesthetic agent required
4ml of LA increases IOP by 6.2
mmHg.
Ocular compression decreases IOP
by 8.8mmHg after 5min &
14.3mmHg after 40min.

COMPLICATIONS :
 Central retinal artery occlusion.
 Intravascular anesthetic injection.
 Perforation of eye with retrobulbar needle.
 Intraocular anesthetic injection.
 Optic nerve impalement with intrathecal injection or
Optic nerve sheath hematoma.
 Brain stem anaesthesia

 Frank convulsion
 Extra ocular muscle palsy
 Decreased visual acuity
 Trigeminal nerve block
 Respiratory and cardiovascular depression.
CONTRAINDICATION :
Bleeding disorder ( risk of retrobulbar haemorrhage)
Extreme myopia ( globe perforation)
An open eye injury (may cause expulsion of intraocular contents)
Posterior staphyloma

PERIBULBAR BLOCK
Most popular now a days
AIM:
 Injected into peribulbar space
 Spreads to lid and other spaces
 Produces globe and orbicularis akinesia and anaesthesia.
POSITION OF PATIENT:
Supine and in primary gaze
VOLUME :
5-10 ml (approximately)

SITE OF INJECTION:
1st: The point between medial 2/3rd &
lateral 1/3rd of lower orbital margin adjacent to infraorbital
notch (3ml)
2nd : Just infero-medial to supra orbital notch or between medial canthus & caruncle. (2ml)
Bevel of needle should be directed toward globe and needle advanced parallel to orbital floor & no redirection
as in retrobulbar block . Hub of needle should not go beyond the inferior orbital rim.

ADVANTAGES :
 Anesthetic agents are deposited outside the muscle cone(extraconal).
 Needle is further away from the globe,blood vessels, optic nerve, & dural sheaths.
 Less pain on injection.
 Less intraoperative posterior pressure creates a softer eye during surgery.
DISADVANTAGES :
 Conjunctival chemosis
 Less akinesia than retrobulbar block
COMPLICATIONS :
 Perforation of eye with peribulbar needle.
 Intraocular anesthetic injection.
 Optic nerve impalement with intrathecal injection or
 optic nerve sheath hematoma.
 Respiratory and cardiovascular depression

PARABULBAR OR SUB-TENON BLOCK
Topical anesthetic (e.g., 0.5% proparacaine)
With blunt Westcott scissors and 0.12 mm forceps, Halfway between inferior limbus &
fornix(5-10 mm lateral to limbus) in inferotemporal quadrant, Conjunctival incision 2-3
mm & dissection of tenon’s fascia to open sub-tenon space.
Using 15 mm, 25G blunt tipped curved cannula or needle
Cannula kept straight ,parallel to the optic nerve
Slowly inject 2–3 ml of LA in the periequatorial region
Bathing the nerves & muscles within the cone .

ADVANTAGES :
Uses cannula as opposed to needle; therefore less chance of penetrating globe or dural
sheath or vessels .
Compression of eye is not required
Very rapid onset and deeper level of anesthesia compared with topical
Reduces patient anxiety, as anesthesia is administered after patient is draped.
Lack of elevation of blood pressure and transitory cardiac arrhythmia
Requires lower volume of anaesthetics
Better anaesthesia to iris and ant.segment
DISADVANTAGES:
Subconjunctival haemorrhage
More post-operative morbidity

FRONTAL BLOCK
AIM: 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 ml of LA .

FACIAL NERVE (Orbicularis/Lid)BLOCK
AIM :
To achieve paralysis of orbicularis oculi muscle to prevent blepharospasm which causes rise of IOP (by10mmHg).
USE :
as an adjunct to retrobulbar block
VOLUME :
total 3–5 ml of LA
25G, 1.5 inch disposable needle
TYPES :
Van lint
O’Brien
Nadbath & Rehman
Atkinson

CLASSIC VAN LINT TECHNIQUE :
Introduce the needle 1 cm behind the lateral margin of
orbit at the level of the inferior orbital rim.
Advance needle horizontally and inject 1–2 ml
subcutaneously along inferotemporal orbital rim while
withdrawing needle.
Then redirected superonasally and inject along the
superotemporal orbital rim.
MODIFIED VAN LINT TECHNIQUE :
1st superior & slightly anteriorly. Do not remove
needle from skin.
2nd inferior and slightly anteriorly.
Supplemented with:
3rd 1 cm inferonasal to original entry site along
inferior orbital rim
4th 1 cm superotemporal to original
entry site along superior orbital rim.

O’BRIEN TECHNIQUE
 Located 1 cm anterior to the tragus of the ear and inferior to the posterior
aspect of the zygomatic process.
 May facilitate identification of condyloid process by feeling its movement
at the temporomandibular joint as patient opens mouth and moves jaw
from side to side.
 Insert needle until the periosteum of the condyloid process is reached.
 Withdraw needle to its tip & then advance it superior & anteriorly over
zygomatic arch.Redirect inferiorly along the posterior edge of ramus of
mandible
 Inject ~2 ml of anesthetic solution.
❏ Do not inject into periosteum.
❏ Do not inject into temporomandibular joint space.

ATKINSON TECHNIQUE :
• The branches of the facial nerve are blocked
• Insert needle subcutaneously at inferior edge of
zygomatic bone directly below lateral orbital rim.
• Advance needle across zygomatic arch, aiming ~30
degrees upward towards top of ear.
• Inject ~3–4 ml of anesthetic solution as needle is
withdrawn
• The technique is not frequently used because of the
high number of failures
NADBATH AND REHMAN TECHNIQUE :
•LA is Injected where the main trunk of the nerve
emerges from the stylomastoideal foramen.
•The injection site is located between the mastoid
process and the posterior edge of the mandible.
•A short needle (12-16 mm) ,2-4 mI of LA injected.
Associated with the highest risk of serious
complications as rapid-onset dysphagia, accumulation
of secretions, laringospasm and distressed respiration
because of ipsilateral paralysis of the IX, X and XI
cranial nerves.
 Permanent facial nerve paralysis(longer needles &
hyaluronidase single injection of a large volume of LA.

LOCAL INFILTRATION & LACRIMAL SAC ANAESTHESIA
For surgeries on lacrimal sac & NLD ,regional anaesthesia is produced by :
1.Blocking nasociliary nerve around the anterior ethamoidal foramen.
 Needle enters orbit a little below the trochlea & is passed backwards along the junction of roof & medial wall
for 3cm.
 Care taken to avoid angular vein.About 1ml lignocaine & adrenaline is injected.
 Redirect needle medially for injection along orbital margin & around the fundus of lacrimal sac.
2.An injection made over anterior lacrimal crest along the line of incision.Redirect needle posteriorly,down &
medially to infiltrate the entrance of NLD.

3. Superior alveolar nerve blocked as it leaves the infraorbital nerve to enter an osseous canal proximal to
the infraorbital foramen.
4.Anaesthesia of nasal mucosa provided by packing nose with ribbon gauze soaked in cocaine 10% +
adrenaline 1:100000,where this done halothane anaesthesia is best avoided. When DCR is to be done ,an
injection of lignocaine 0.25-0.5ml is made to raise the nasal mucosa from the bone at the site of ostium.
ANAESTHESIA FOR STRABISMUS SURGERY:
1.Done under GA
2.Rarely under LA-muscle belly behind the equator is infiltrated with 1ml 2% lignocaine with adrenaline.
Caution taken not to pull on muscle as it causes: aching pain,nausea,vomiting,changes in pulse.

MAJOR SIGHT & LIFE-THREATENING COMPLICATIONS
A. RETROBULBAR HAEMORRHAGE :
• Retrobulbar hemorrhage following retrobulbar injection has been reported between
0.074% to 2% .
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.
(r/o CRAO ).
Immediate medical treatment:
intravenous osmotic agents such as –
 acetazolamide
 Mannitol

Surgery:
Surgical decompression such as -
 Canthotomy,
 Cantholysis
 Orbital decompression
Jaffe et al29 recommended postponing the surgery
till one week.
General anesthesia is considered in patients having
repeated retrobulbar hemorrhage.

B. GLOBE PERFORATION:
oPenetration of globe can occur with both retrobulbar and peribulbar blocks.
oRate of scleral penetration reported by Hamilton et al is one out of 5235
retrobulbar injections and not a single perforation out of 6705 peribulbar
injections.
oDavis and Mandel reported the rate of globe perforation in one out of 16224
cases (0.006%)
oHigh myopes (AL >26 mm) & soft eyeball patients are more prone .

SIGNS AND SYMTOMS :
o Sudden & marked pain during the delivery of local anaesthesia.
o Hypotony with inability to secure a stable globe - intraoperative signs of perforation.
o reduced red reflex due to vitreous haemorrhage.
o Loss of vision.
o Serious sight threatening vitreoretinal complications viz retinal detachment and intraocular
hemorrhage.
If a penetrating or perforating wound is suspected, it is not advisable to explore the sclera since needle
entry site is small and self-sealing.
seek the advice of a specialist vitreoretinal surgeon

C. OPTIC NERVE INJURY
Optic nerve may be damaged by:
●● Direct injury to the optic nerve or central retinal vessels by the retrobulbar needle with resulting optic
atrophy or secondary intraocular hemorrhage due to presumed damage to retinal artery or vein have been
reported.
●● 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.
The position of the globe may influence the rate of injury.
Placing the eye in the primary position reduces the danger of nerve or vessel damage.
Avoiding long needles & deep injections into the orbit.

D. MUSCLE PALSY (non sight threatening )
 Incidence of postoperative ptosis (of 2 mm or more) after cataract surgery were reported between 0 to
20%.Incidence of diplopia is less than 1 % reported by Davis and Mandel.
 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
Causes of prolonged postoperative diplopia & ptosis :
 Intramuscular injection
 Local anaesthetic myotoxicity
 Ischaemic contracture following haemorrhage/trauma
 Others: Eyelid speculum
Bridle suture
Pressure on the globe and upper lid &
Prolonged upper lid patching.

E. BRAIN STEM ANAESTHESIA
• Due direct injection of local anaesthetic into optic nerve sheath & subsequent travel to the CNS
via subdural or subarachnoid space.
• Incidence of CNS complications following retrobulbar anesthesia ranges from 0.09% to 1.5%.
SYMPTOMS & SIGNS:
 amaurosis
 drowsiness
 light-headedness
 confusion
 loss of verbal contact
 loss of consciousness
 shivering & tachycardia

 cranial nerve palsies
 convulsions
 respiratory depression or respiratory arrest
 cardiac arrest .
ONSET OF SYMPTOMS: delayed 2-40mins of LA injection
SYMPTOMS LASTS FOR: Hours
MANAGEMENT :
• Early and prompt treatment
• 100% oxygen
• maintenance of vital signs
• tracheal intubation and controlled ventilation
Placing the eye in the primary position reduces it.

F. OCULOCARDIAC REFLEX (Trigeminovagal Reflex)
Trigeminal nerve – afferent and vagal efferent pathway
CAUSES:
• Traction on extra-ocular muscle
• Pressure on globe
SEEN DURING:
• Eye muscle surgery
• Detached retina repair
• Enucleation
RESULT:
 Bradycardia
 Ventricular ectopy
 Ventricular fibrillation
Factors contributing to the
incidence of the
oculocardiac reflex:
o Preoperative anxiety
o Hypoxia
o Hypercarbia
o Increased vagal tone
owing to age

AFFERENT PATHWAY
Impulses
Long & short cilliary nerve
Cilliary ganglion
Trigeminal gasserian ganglion
main trigeminal sensory nucleus
in the floor of the 4th ventricle

EFFERENT PATHWAY
Cardiovascular 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.
 Local injection of lidocaine near the eye muscle
Atropine (0.01 mg/kg IV)/ Glycopyrrolate (anti-cholinergic):
often helpful immediately or prior surgery

REFERENCES :
1. Stallard’s Eye Surgery –M J Roper Hali. seventh edition
2. Cataract surgery-Roger F. Steinert.third edition
3. Ophthalmic surgical procedures-Peter S Hersh .second edition
4. Clinical Ocular Pharmacology and Therapeutics-SK Gupta.second edition
5. Clinical Anatomy of Orbit and Common Orbital Disease-Dr.M.Kokilam
6. Parsons’ Diseases of the eye-Ramanjith Sihota,Radhika Tandon.twenty second edition
7. Yanoff & Duker ophthalmology-third edition
8. Wolff’s anatomy of the Eye & Orbit-eighth

Ocular anaesthesia by dr.roopashree.c .r

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