orbital anatomy local anesthetic agents methods and complication

1. Anesthesia in
Ophthalmic Surgery
Panit Cherdchu
Ophthalmology department
Phramongkutklao Hospital

2. OUTLINE
Review of Anatomy
Anesthetic Agents
Type of Anesthesia
Take Home Message

3. ORBITAL ANATOMY

4. measurement
“The orbital entrance
averages approximately 35
mm in height and 45 mm in
width”
“depth varies from 40-45 mm
from the orbital entrance to
the orbital apex”

5. 7 BONES

6. Superior orbital fissure
Inferior orbital fissure
Optic canal
Infraorbital foramen

9. Frontal Ethmoidal
Maxillary Sphenoidal
Periorbital Sinuses

10. Ciliary Ganglion
• A long sensory
root
• A short motor
root
• A sympathetic
root

11. EOMExtraocular muscles

12. MUSCLES
• 4 Rectus: SR-IR-LR-MR
• 2 Oblique: SO-IO
• 1 Protractor: Orbicularis Oculi Muscle
• 1 Retractor: Levator Palpebral Superioris Muscle-
Muller’s muscle

13. “The relationship between the muscle insertions and
the ora serrata is clinically important. A misdirected
suture passed through the insertion of the superior
rectus muscle could perforate the retina”

14. Levator is
innervated by
CN III
1. skin
2. eyelid margin
3. subcutaneous connective tissue
4. orbicularis oculi muscle
5. orbital septum
6. levator palpebrae superioris muscle
7. Müller muscle
8. tarsus
9. conjunctiva

15. 3 parts of orbicularis
oculi muscles

16. “The Tenon capsule (the fascia bulbi) is an envelope of elastic
connective tissue that fuses posteriorly with the optic nerve sheath
and anteriorly with a thin layer of tissue called the intermuscular
septum, which is located 3 mm posterior to the limbus”

17. Vascular Supply and Drainage of the Orbit
Vascular Supply and Drainage of the Orbit

20. Internal carotid artery and external
carotid artery collateral anatomy
• 1, internal carotid;
• 2, external carotid;
• 3, facial;
• 4, maxillary;
• 5, superficial temporal;
• 6, transverse facial;
• 7, middle meningeal;
• 8, frontal branch of superficial temporal;
• 9, ophthalmic;
• 10, lacrimal;
• 11, recurrent meningeal;
• 12, supraorbital;
• 13, supratrochlear;
• 14, angular;
• 15, palpebral;
• 16, zygomaticotemporal;
• 17, zygomaticofacial;
• 18, deep temporal;
• 19, infraorbital;
• 20, muscular.

21. 3 main outlets of venous system
– Superior and inferior ophthalmic v. cavernous
sinus&cranial system
– Anastomosis of the ophthalmic v.&angular v.
facial venous system
– Inferior orbital fissure pterygoid venous plexus

24. NEUROANATOMY
• Cranial Nerve II
• Cranial Nerve III
• Cranial Nerve IV
• Cranial Nerve V
• Cranial Nerve VI
• Ciliary Ganglion
NEUROANATOMY

25. MOTOR NERVE

29. Local Anesthetic Agents

30. “The local anesthetic drugs used in
ophthalmology are tertiary amines linked by
either ester or amide bonds to an aromatic
residue”

31. “Protonated form(inside myelin sheath) blocks
the sodium channels on the inner wall of the cell
membrane and increases the threshold for
electrical excitability. As increasing numbers of
sodium channels are blocked, nerve conduction
is impeded and finally blocked”

32. • block the poorly myelinated and narrow
parasym&sym fibers
• Optic nerve is usually not impeded by retrobulbar
block
• Myelinated motor fibers (akinesia)
• Sensory fibers (pain+temp)

35. TOXIC
• The toxic manifestations of local anesthetics
are generally related to dose
• severe hepatic insufficiency
• even at lower doses. These manifestations
include restlessness and tremor that may
proceed to convulsions, and respiratory and
myocardial depression

36. EPINEPHRINE
• local anesthetics block sympathetic vascular
tone and dilate vessels,
• a 1:200,000 concentration of epinephrine is
frequently added to shorter-acting drugs to
retard vascular absorption

37. LIDOCAINE
• Lidocaine is an amide local anesthetic used in
strengths of 0.5%, 1%, and 2% (with or
without epinephrine) for injection
• It yields a rapid (5-minute) retrobulbar or
eyelid block that lasts 1–2 hours.

38. MEPIVACAINE
• Mepivacaine is an amide drug used in
strengths of 1%–3% (with or without a
vasoconstrictor).
• rapid onset and lasts approximately 2–3
hours. The maximum safe dose is 25 mL of a
2% solution.

39. BUPIVACAINE
• poor akinesia but has the advantage of a long
duration of action, up to 8 hours.
• mixture with lidocaine or mepivacaine to
achieve a rapid, complete, and long-lasting
effect.
• The maximum safe dose is 25 mL of a 0.75%
solution.

40. HYALURONIDASE
• combined with local injection of anesthetics to
increase the dispersion of the anesthetic drug
• More dispersion reduce the pressure rise in
the limited orbital space, produce less
distortion of the surgical site, decrease the risk
of postoperative strabismus and myotoxicity,
and increase akinesia of the globe and lid

41. HYALURONIDASE
• lower volumes of anesthetic agent.
• For retrobulbar or peribulbar injection, 1 mL
of hyaluronidase can be added to a syringe of
the anesthetic to be administered.

42. Type of Anesthesia

43. FACIAL NERVE BLOCK
LOCAL
ANESTHESIA
Topical Anesthetic Block
Subconjunctival Block
Intracameral Block
GENERAL
ANESTHESIA
REGIONAL
ANESTHESIA
Peribulbar Block
Parabulbar Block
Retrobulbar Block

44. LOCAL ANESTHESIA
• Topical Anesthesia Block
– Block superficial cornea and conjunctiva
– Block long and short ciliary nerve, nasociliary
nerve, lacrimal nerve
– Disrupt intercellular tight junction

45. LOCAL ANESTHESIA
• Subconjunctival block
– Anterior segment is blocked but no akinesia
– At posterior to phaco incision/ perilimbal
conjunctiva

46. LOCAL ANESTHESIA
• Intracameral block
– Anesthetic agent: 0.2-0.5 ml of unpreserved 1%
lidocaine hydrochloride
– If absence of posterior capsulemight cause
transient retinal toxicity “Transient Amaurosis”

47. Regional anesthesia
• Parabulbar block (sub-tenon block)
– Inferonasal, inferotemporal
– Inject anesthetic agent into sub-tenon space
– Patient look upward+outward
– Drug : 2% lidocaine, +hyaluronidase

48. Method
– Grab conjunctiva+Tenon’s capsule with blunt non-
toothed forceps
– Small cut with westcott scissors
– Blunt curved posterior sub-tenon’s cannula with
local anesthetic
– Move along the curvature of the sclera
– Inject anesthetic agent into sub-tenon space

49. move along the
curvature
BLUNT curved

50. • Expected outcome
– Akinesia
– Mydriasis
– Analgesia
– Hypotonia of lidsptosis

51. Button hole formed ~10 mm from the
corneal limbus

52. Freeing the Quadrant

53. Lacrimal cannular

54. Insertion of cannula and injection of
anesthetic.

55. • Still!!
– Superonasal block is indicated as supplementary
block
– Locate the needle at upper eyelid vertically above
the medial limbus
– Intermittent of ocular compression (10-
20minutes)

56. Pros cons
Reduce retrobulbar
hemorrhage accident
Might not achieve at
akinesis effect
Reduce risk of injury at
globe or optic nerve
Larger volume is needed
Reduce risk of intradural
injection
More incidence of
periorbital
ecchymosis+chemosis

57. Regional anesthesia
• Peribulbar block (Extraconal block)
– Inject into extraconal spacedrug spread to
whole area including intraconal area
– The larger space to apply, the more volume of
drug is needed.

58. Method
– Patients lies in supine + neutral position
– ¾ inch, 24-26G needle
– Anesthetic agent: 5ml of 0.75%bupivacaine// 5 ml
of 2%lidocaine with 1:200,000 adrenaline//150
units of hyaluronidase

59. Method
– Point at lateral1/3 and the medial 2/3 of the
inferior orbital edge
– Directed to the apex of the orbit
– at equator of globe

60. • Retrobulbar block (intraconal block)
– 25G, 1 ½ inches needle
– Neutral position
– Point at lateral 1/3 and medial 2/3 of inferior orbital
edge
– Posteriorly parallel to the orbital floor, incline of 15
degree
– Pass equatorshift to medially and superiorly angle
of 45 degree
– Depth 25-35 mm
– Compress for 15 sec on5 sec off for 1-2 minutes
Regional anesthesia

61. • Akinesia and Anesthesia are quickly ensure
the complete block

62. Retrobulbar Block - Step 1
• Enter just inferior to the globe and
perpendicular to the plane of the face.

63. Retrobulbar Block - Step 2
• Once you feel the first pop through the orbital
septum, angle 45 degrees medially and 45
degrees superiorly towards the apex of the
orbit until the second pop through the muscle
cone is felt.

64. Retrobulbar Block - Injection
Pull back on the syringe to ensure the needle is
not in a vessel, then inject 3-5 cc of anesthetic,
palpating the globe to assess for posterior
pressure

65. Pros Cons
Low volume of drug Risk of retrobulbar
hemorrhage
High potency of blocking Oculocardiac reflex
Rapid onset CRAO
Puncture into globe,optic
nerve
Risk of brain stem
anesthesia
Epinephrine toxicity

66. Retrobulbar hemorrhage

67. • increasing proptosis with tight eyelids,
subconjunctival and periorbital haemorrhage,
and a dramatic increase in intraorbital
pressure

68. Lateral Canthotomy

69. Oculocardiac reflex
• rapid distension of the tissues by volume or
haemorrhage provoke it occasionally
• Bradycardia, Junctional Rhythm, Asystole

70. Central Retinal Artery Occlusion
• Sudden, complete, and painless loss of vision
• Must!! immediately reduce the IOP

71. Puncture into globe
• myopic eyes which are longer but also thinner
• globes longer than 26 mm are at risk
• A diagnosis of perforation may be made by
pain at the time the block is performed,
sudden loss of vision, hypotonia, a poor red
reflex or vitreous haemorrhage

73. Puncture into optic nerve

74. Brainstem Anesthesia
• Onset can be 2-40 minutes after injection
• symptoms are drowsiness, vomiting,
contralateral blindness caused by reflux of the
drug to the optic chiasm, convulsions,
respiratory depression or arrest, neurological
deficit, cardiac arrest

75. Brainstem Anesthesia

76. FacialNerveBlock

77. Van Lint Method
• 1 cm below and
behind the
lateral canthus

78. O’Brien’s Method
• The
condyloid
process of
the
mandible

79. Atkinson Method
• At Inferior edge of
the zygomatic
bone

80. Nadbath Ellis Method
Where facial nerve
first emerges from
stylomastoid
foramen

81. THE END