Anaesthesia in ophthalmic surgery - Peribulbar block, retrobulbar block, topical anesthesia, facial nerve block, sub tenon block, General anaesthesia

1. ANESTHESIA IN
OPHTHALMIC SURGERY
AND COMPLICATIONS
Dr. Sameeksha Agrawal

2. Objectives of anaesthesia in
intraocular surgery
• Akinesia of globe and lids
• Anaesthesia of globe and lids and adnexa
• Control of intraocular pressure
• Control of systemic blood pressure
• Relaxation of patient
• Absence of untoward reactions
• Smooth emergence
• Adequate post-operative analgesia

3. Anatomy
• Orbit – shape of irregular pyramid
– Base at front
– Axis points posterio-medially towards skull
• Globe lies in anterior part of orbit
- sits high and lateral

4. Anatomy
• Origin of recti muscles from Annulus of Zinn and their
attachment to globe forms a cone around the globe

5. • The Intraconal compartment include –
 Optic nerve
 Ophthalmic artery and vein
 3rd nerve
 6th nerve
 Nasociliary nerve
 Ciliary ganglion
 Retrobulbar block is aimed at blocking structures of
intraconal compartment

6. • The ciliary ganglion, a parasympathetic ganglion, lies
approximately 1 cm from the posterior boundary of the
orbit between the lateral surface of the optic nerve and the
ophthalmic artery.

7. • Cranial nerve IV is not affected by retrobulbar block since
it lies outside the muscle cone
• When the retrobulbar block is performed, the local
anesthetic is delivered within the muscle cone itself
• During a peribulbar injection, however, the injection is
outside the muscle cone and spreads by way of diffusion to
block the orbital nerves, including the IV nerve.

8. TECHNIQUES OF ANESTHESIA
• Facial nerve block
• Retrobulbar block
• Peribulbar block
• Sub Tenon block
• Topical anesthesia
• General anesthesia

9. GENERAL VERSUS LOCAL ANESTHESIA
• The choice of general versus local anesthesia
is made on the basis of
– the duration of the surgery
– the relative risks and benefits of each
technique for the patient
– patient preference

10. General versus Local Anesthesia
General
Anesthesia:
Patient
refusal
Children /
movement
disorders
Major /
lengthy
procedures
Inability to lie
still / flat-
Kyphosis
Local
Anesthesia:
No Physio-
logical
disturbance
Economic,
Day care

11. LIMITATIONS
General Anesthesia:
Eye surgery necessitates
positioning the
anesthesiologist away
from the patient’s
airway
Patients at extremes of
age
Pediatric patients :
associated congenital
disorders (eg: rubella
syndrome, Down
syndrome).
Co-morbidity in elderly:
esp.coronary artery disease
Local Anesthesia:
Complications, Allergy
to drug
Shortness of breath
on lying down,
chronic cough
Parkinson’s disease
Eye Trauma

12. RETRO- AND PERIBULBAR LA
• The aim of an Retrobulbar block is to deliver LA within the space
bound by the rectus muscles (the ‘intraconal space’)
• The aim of a Peribulbar block is to deliver anesthetic outside of the
muscle cone
• These two compartments are continuous allowing injectate to diffuse
from one to the other
• The closer the needle-tip either to the orbital apex or to the back of the
globe, the more rapid is the onset of anesthesia and more is the danger
of damage

13. Techniques of peribulbar block

14. Techniques of peribulbar block
• 5 ml bupivacaine 0.5% and 5 ml lignocaine 2%
• 150 units of hyaluronidase (mixed to aid diffusion within the
orbital tissue) are drawn into a 10 ml syringe.
• Superior & inferior injections of 5 ml each are given with 3/4
inch, 24-26G needle
• Inferior injection is given at the junction of the outer one
third & inner two third of the lower orbital rim

15. Techniques of peribulbar block
• Gently press on the lower lid between the orbital margin and
the globe to feel the inferior orbital notch and with the other
hand progressively inject 5 ml of anesthetic solution starting
just under the skin, progressively to just behind the equator of
the globe.

16. Sites
• INFEROTEMPORAL
• SUPERONASAL
• MEDIAL

17. Position Of Eyeball
• Lower outer corner of the orbit at a point on a line drawn
vertically down from the outer canthus to the infraorbital margin
•23 gauge needle no longer than 1 inch is directed paralleling the
wall of the orbit with the patient's gaze in the primary position.

18. Guiding Of Needle
• The needle should be slowly advanced, stopping immediately
– if there is either a tugging movement of the globe, which may
indicate snagging of the needle on sclera or an extraocular
muscle (EOM), or
– if there is either severe pain or resistance to injection, either of
which can indicate injection into the globe
• Prior to injection, the practitioner must ensure that the needle
is not intravascular by drawing back on the syringe
• Monitor the IOP digitally through the eyelid

19. Specific Contraindications
• An AL of greater than 26 mm is a relative contraindication to Retrobulbar
and Peribulbar block
- This should be regarded as absolute if imaging has not been performed
• Excess warfarin/coumadin anticoagulation, as measured with international
normalized ratio (INR) is said to increase the chance of orbital
haemorrhage
- The INR should be within the range specified by the prescribing physician

20. Complications of Peribulbar Block
Either from the agents used
Or
The block technique itself

21. Complications
• Central spread of anesthetic
• Globe perforation
• Venous orbital hemorrhage
• Arterial orbital hemorrhage
• Oculocardiac reflex
• Allergic reaction
• Ophthalmoplegia - direct damage to the EOM or its nerve
• Optic nerve damage

22. Central spread of anesthetic
• Life-threatening complications can result from intrathecal
spread
• Injectate spreads along the optic nerve and causes central
effects with bradycardia, and cardiac and respiratory arrest
• Less common in Peribulbar block, but in practice, because
repeated injection of anesthetic and large total volumes are
required, it may be more likely

23. OCULAR PENETRATION AND
PERFORATION
• Most common in the myopic, elongated globes
• Myopics with staphyloma
• Associated with the use of large, dull needles

24. • Sudden appearance of hypotony
• A sensation of "poking through ”during the placement of the
needle.
• If the needle catches the sclera, the cornea first moves
toward the needle and then suddenly away from it as the
needle passes through the sclera.
• It is often painful, but not always noticed at the time.
• Surgeon might notice the absence of the red reflex, an
excessively soft eye or an excessively hard eye with cloudy
cornea if LA has been injected inside the eye.
OCULAR PENETRATION AND
PERFORATION

25. • Sometimes, the procedure is uneventful and the telltale
retinal appearance may be noticed years later on routine
fundoscopy.
• Even with immediate recognition, the visual prognosis for
such an eye is poor.
OCULAR PENETRATION AND
PERFORATION

26. OCULAR PENETRATION AND
PERFORATION
• Diagnosis -Indirect fundoscopy
• The most common sequelae- Retinal detachment
• Appropriate retinal surgery-to prevent the loss of vision

27. How to avoid Perforation ?
• Ask the patient to look in primary gaze
• Needle should be exactly straight when longer eyeball
• If longer eyeball, 26G needle should be used
• Put finger between globe and orbital rim before inserting needle
• Don’t move when the needle is inside
• Don’t inject against resistance
• Look for early signs of perforation-
- Hypotony
- Severe pain
- Loss of glow
- Tugging of eyeball

28. Venous orbital hemorrhage
• This is common with both Retrobulbar LA and Peribulbar LA
• There is slow proptosis with variable bruising of the lids and
subconjunctival hemorrhage coming on over a 5 min period
• The orbit becomes tense and it may be difficult to open the
eyelids
• Benign and self-limiting

29. Arterial orbital hemorrhage
• This is rare and is similar to the severe orbital hemorrhage
usually seen with severe facial fracture
• The features are identical to venous orbital hemorrhage, but
with faster onset and more pressure
• Demand pressure reduction with lateral canthotomy, orbital
drainage
• Surgery must be postponed and the compromised eye
protected

30. Ophthalmoplegia
• Prolonged diplopia has been described after both Retrobulbar
LAand Peribulbar LA
• One obvious cause is direct damage to the EOM or its nerve
• Myotoxicity due to high concentrations of anesthetic round
the EOM when hyaluronidase is not used has also been
reported
• Hyaluronidase allows the injectate to spread more easily and
thus reduces the concentration of anesthetic around the EOMs

31. OCULOCARDIAC REFLEX
The Oculocardiac Reflex(OCR) is manifested by
• Bradycardia
• Bigeminy
• Ectopics
• Nodal rhythm
• Atrioventricular block
• Cardiac arrest

32. OCULOCARDIAC REFLEX
Caused By:
• Traction on the extraocular muscles (medial rectus)
• Ocular manipulation
• Manual pressure on the globe
The OCR is seen during:
• Eye muscle surgery
• Detached retina repair
• Enucleation

33. OCULOCARDIAC REFLEX
• Factors contributing to the incidence of the oculocardiac reflex:
– Preoperative anxiety
– Hypoxia
– Hypercarbia
– Increased vagal tone owing to age

34. OCULOCARDIAC REFLEX
Management
• stop stimulation by the surgeon before the arrhythmia
progresses to sinus arrest
• Atropine (0.01 mg/kg IV)
• local injection of lidocaine near the eye muscle
Ensure
• depth of general anesthesia
• normocapnia
• surgical manipulation is gentle.

35. OCULORESPIRATORY REFLEX
• May cause shallow breathing, reduced respiratory rate and
even full respiratory arrest.
• Trigemino vagal reflex- connection exists between the
trigeminal sensory nucleus and the pneumotactic centre in
the pons and medullary respiratory centre.
• Commonly seen in strabismus surgery
• Atropine has no effect.

36. OCULOEMETIC REFLEX
• It is likely responsible for the high incidence of vomiting after
squint surgery (60-90%).
• Trigemino-vagal reflex with traction on the extraocular
muscles stimulating the afferent arc.
• Antiemetics may reduce the incidence, a regional block
technique provides the best prophylaxis

37. Advantages of peribulbar block over
retrobulbar block
Safer than retrobulbar anesthesia due to:
• 1. Less chances of retrobulbar haemorrhage
• 2. Perforation of eye or injury to the optic nerve.
• 3. The potential for intraocular or intradural injection is
decreased because the anesthetic is deposited outside the
muscle cone.

38. Disadvantages of peribulbar block
1. Akinesia of the extra-ocular muscle may be less complete
2. Greater volume required, more time required to achieve
satisfactory block
3. Greater incidence of periorbital ecchymosis & conjunctival
chemosis

39. Facial nerve block
Anatomy -
• The facial nerve passes from the stylomastoid foramen into
the substance of the parotid gland, and 5-7 mm behind the
ramus of the mandible
• It divides into two divisions: temporofacial and cervicofacial
• The temporofacial division which supplies orbicularis oculi
muscle lies on the neck of the condyle

40. • Orbicularis oculi akinesia is effected by
one of the following methods :
1. O’Brien’s method - aims at blocking the
facial nerve at the proximal trunk
2. Van Lint method : Facial nerve is blocked in the region of
the terminal branches of the facial nerve
An intradermal wheal of local anesthetic is raised at a point
about 1 cm below and behind the lateral canthus

41. 3. Atkinson method: Injection is given along the inferior edge
of the zygomatic bone and then upward across the zygomatic
arch toward the top of the ear
4. Nadbath Ellis method : Injection is
made in the area of the facial nerve as
it emerges from the stylomastoid
foramen and enters the parotid gland

42. FACIAL NERVE BLOCK COMPLICATIONS
• Disturbances of swallowing and respiratory difficulties
(Blocking of main trunk of facial nerve after its exit from stylomastoid
foramen may be associated with unilateral block of Vagus,
glossopharyngeal and spinal accessory nerve)
• Horner's syndrome
• Permanent facial nerve paralysis- longer needles and hyaluronidase
use of a single injection of a large volume of LA

43. SUBCONJUNCTIVAL LOCAL ANESTHESIA
• This technique is usually used as an adjunct to TA,
especially if there is to be manipulation of the sclera such
as in scleral tunnel or filtering surgery
• Contraindications –
presence of a significantly scarred conjunctiva

44. • Technique-
-Adequate TA and insertion of 5% Povidone iodine into the
conjunctival fornix
-The conjunctiva is perforated with a 26 gauge needle with the
bevel down to minimize the chances of inadvertent
perforation of deeper structures
-Anesthetic is slowly injected
-A well-defied bleb indicates subconjunctival injectate
• Complications
-SCH and chemosis
SUBCONJUNCTIVAL LOCAL ANESTHESIA

45. TOPICAL ANESTHESIA
• Fastest LA (onset and recovery)
• Least daunting for patient
• Least depth of anesthesia
• Low rate of systemic and local complications
• Specific Contraindications
-It is contraindicated in patients unable to respond to command
and those with photosensitivity

46. Characteristics –
• There is surface anesthesia which does not spread to the
sclera
• Supplemental anesthesia is required for scleral procedures
• The onset is rapid (minutes only)
• There is no akinesia which allows the patient to move the eye
on command
• As there is no amaurosis, the operating microscope light
needs to be increased slowly to the optimal level.
TOPICAL ANESTHESIA

47. SUB-TENON'S LOCAL ANESTHESIA
• Parabulbar anesthesia
• Insertion of anesthetic directly into sub-Tenon's space via a
blunt cannula
• Almost immediate anesthesia (depth is volume
dependent)
• Almost no danger of perforation or central spread
• Contraindicated if there is any cause of obliteration of sub-
Tenon's space (e.g., recurrent previous sub-Tenon's
injections, scleritis, previous retinal detachment surgery)

48. Complications-
• Subconjunctival haemorrhage and chemosis
• Perforation
• Central spread
• Post-STLA “orbital cellulitis'‘
• Ophthalmoplegia
SUB-TENON'S LOCAL ANESTHESIA(STLA)

49. Specific Clinical Situations
and Complications

50. STRABISMUS SURGERY
Problem
• the possible increased risk of malignant hyperthermia
• the high incidence (Post operative Nausea and
vomiting - PONV)
• the likelihood of an Oculocardiac reflex
Solution
• avoid succinylcholine and halothane
• i.v lidocaine (1.5 mg/kg)
• low-dose ondansetron (50 µg/kg)
• dexamethasone (150 µg/kg) regimen

51. STRABISMUS SURGERY
• PONV is common postoperatively, up to 50 – 75%.
• Giving two anti-emetic agents such as ondansetron 0.1
mg/kg IV and dexamethasone 0.1-0.2 mg/kg IV can reduce
this to 10%.
• Ideally extubate in deep plane.
• Analgesia should include topical tetracaine or
oxybuprocaine, NSAIDS such as ibuprofen or diclofenac
and paracetamol, unless contraindicated.

52. STRABISMUS SURGERY
• Intraoperative opioids should be avoided due to the high
incidence of PONV, but where necessary, consider the use of
fentanyl.
• A peribulbar block is effective for analgesic requirements and
reduces PONV, possibly by blocking the ophthalmic division of
the trigeminal nerve that passes to the vomiting centre in the
medulla.
• A sub-Tenon block performed intraoperatively by the surgeon
can be very effective for analgesia.

53. VITREORETINAL SURGERY
• Avoid nitrous oxide if an intraocular gas bubble is used.
• Avoid nitrous oxide in patients who have had an intraocular
bubble placed for several weeks after the procedure.
• Controlled ventilation and paralysis should be considered for
maintaining a still eye and avoiding raised IOP during the
procedure.

54. VITREORETINAL SURGERY
• This procedure is painful and analgesia including opioids
should be considered.
• Anti-emesis should be used routinely
• Avoid raised IOP during extubation – extubate deep.

55. CONCLUSION
• Anesthesia for eye surgery posses unique challenges.
• Knowledge of ocular anatomy is important to prevent
retrobulbar hemorrhage and other complications.
• With intraocular procedures, profound akinesia and
meticulous control of IOP are requisite.
• However, with extraocular surgery, the significance of IOP
fades, whereas concern about elicitation of the oculocardiac
reflex assumes prominence.

56. CONCLUSION
• Intraocular pressure are affected by physiological factors,
anaesthetic drugs and technique. The regulation of IOP is
important as increase in it can cause extrusion of the vitreous
humor and loss of vision.
• Ophthalmic drugs may significantly alter the patient’s reaction
to anesthesia.
• Regardless of the technique, ventilation and oxygenation must
be monitored, and equipment to provide positive pressure
ventilation must be immediately available .

57. CONCLUSION
• Goal of general anaesthesia is to provide: Smooth intubation,
Stable IOP, Avoidance of severe oculocardiac reflexes, a
motionless field and Smooth emergence
• The complications of ophthalmic anesthesia are rare and can
be both vision- and life-threatening.
• Complications involving the intraocular expansion of gas
bubbles can be avoided by discontinuing nitrous oxide at least
15 min prior to the injection of air or SF6, or by avoiding the use
of nitrous oxide entirely .

58. THANK YOU