Ophthalmic Procedures Anesthesia Related to the Eye Jan Myers SRNA Georgiann Pavlich SRNA

1. Ophthalmic Procedures & Anesthesia Related to the EyeJan Myers SRNAGeorgiann Pavlich SRNA

3. Anatomy & Physiology of the Eye

4. Anatomy of the Eye

5. Bones of the eye

6. Eye Orbits:  Are Pyramid Shaped Structures

7. Orbits Each orbit contains the following structures: Globe Orbital Fat Extraocular muscles Port of the lacrimal apparatus. Nerves Blood Vessels

8. Orbits The orbits of the eye extend from the base at the front, & pointing posterior/medially toward the apex. At the apex is located the optic foramen, which transmits the optic nerve and its vessels. Also found in this area are the superior and inferior orbital fissures which also transmits nerves & vessels

9. Extraocular muscles

10. Extraocular Muscles Extraocular Muscles work with combined action. Consist of 4 rectus & 2 oblique muscles. Allow for full ROM of the eye, including Elevation Depression Abduction Adduction

11. Motor Nerve Supply Lateral Rectus Muscle supplied by: CN VI (Aducents) Superior Oblique supplied by: CN IV (Trochlear) Remainder supplied by: CN III (Occulomotor)

12. Sensory Nerve Supply Sensory supply to the eye is provided by: CN V (trigeminal) its ophthalmic division. Vision is supplied by CN II (optic).

13. Sensory Nerve Pathway: Optic Nerve

14. Orbital Fat Contains two compartments: Central compartment (retrobulbar & intracone) Peripheral compartment (peribulbar & pericone) The importance of the orbital fat, is that it contains the motor & sensory nerves for the eye. Therefore regional anesthesia can be injected into the fat and provide the patient with an effective block.

15. Orbital Fat

16. Optic Foramen

17. Optic Foramen The angle between the lateral walls of the two orbits is 90 degrees. The angle between the later and medial walls of each orbits is 45 degrees The medial walls of the orbit are parallel to the sagittal plane which run directly from the front to the back of the body.

18. The Globe The globe or eyeball itself is positioned at the anterior part of the orbital cavity. It lies closer to the roof of the orbit than the floor. The sclera is the fibrous layer that surrounds the globe except the cornea. The optic nerve penetrates the sclera posteriorly & 1-2 mm medially. The central retinal artery & vein follow the optic nerve pathway.

19. Axial Length Corneal surface to the retina: Normal 25 mm (range 12-35) Large eye: >26mm Is many times measured preop. Larger globes carry increased risk of perforation when regional anesthetics are performed.

20. Intraocular Pressure Normal IOP = 10-22 mmhg Abnormal IOP >25 mmhg IOP is determined primarily by the rate of production of the aqueous humor compared to the rate of IOP drainage.

21. Factors that increase IOP Hypertension Hypercarbia Hypoxia Laryngoscopy Intubation Venous congestion T-burg position Improper prone Vomiting position Bucking Airway obstruction External pressure on Sux the eye Ketamine Retrobulbar hemorrhage Coughing

22. Factors that decrease IOP Diuretics Volatile Agents Mannitol NDMR CNS depressants Hypothermia Hypocarbia Head elevation Ganglionic blockers Diamox Most IV anesthetics

23. Techniques to avoid increased IOP Avoid direct pressure on the eye itself Avoid increased central venous pressure Avoid drugs that increase IOP: Sux, Ketamine

24. Oculocardiac Reflex Stimulated by: Increased pressure on the globe Traction of extrinisic eye muscles Ocular regional anesthesia techniques Results in: Cardiac Arrhythmias Bradycardia Asystole ( and severe increased sphincter tone for the anesthetist)

25. Oculocardiac Reflex Stimulation causes to activation of an Afferent Arc via CN V, trigeminal. Efferent Arc via CN X, vagus. Treatment: STOP STIMULATION! Verify adequate ventilation & oxygenation Atropine IVP .01-.02mg/kg (pretx does not always prevent reflex) May also need local anesthetic infiltration Via retrobulbular block or peribulbar block. Severe Cases: May need to perform CPR.

26. Oculocardiac Reflex Reflex usually subsides with repeated stimulation More common in strabismus surgery with pediatric pts. Can occur in all age groups. Be vigilant, be prepared.

27. Pathophysiology: Eye abnormalities Will review: Cataracts Strabismus Detached Retina Glaucoma

28. Cataracts

29. Vision obscured by cataracts

30. Cataracts Cataracts produce a clouding effect over the visual field of the eye. Cataracts develop slowly over time. Pts c/o blurred vision, sensitivity to light, double vision in effected eye. Types: Nuclear: over center of eye. Cortical: over edges of eye Subscapular: found under the capsule of the lens, are small.

31. Cataracts: Risk Factors Age Diabetes Smoking Previous eye surgery Previous eye inflammation Prolonged use of corticosteroids

32. Strabismus

33. Strabismus What is strabismus?  Strabismus is a visual defect that causes the eyes not to point in the same direction. What is adult strabismus? After childhood, strabismus (misalignment of the eyes) will often result in double vision (diplopia). EsotropiaInward turning of one or both eyes. ExotropiaOutward turning of one or both eyes. Accomodative EsotropiaTurning inward of the eyes because the eye is working hard too hard to focus to try to see clearly.

35. Types of strabismus

36. Right eye deviated outward Exotropic

37. Detached Retina A detached retina : The retina is a thin sheet of light-sensitive nerve tissue and blood vessels that line the back of the eye. The sensory layer of the retina, which receives images and transmits them to the brain, can be pulled away (detached) from its normal position in the back wall of the eye, resulting in vision loss. The retina often detaches from the back of the eye in a manner similar to wallpaper peeling off of a wall. The detachment is usually preceded by a hole or tear in the retina.

38. Detached Retina

39. Detached Retina

41. Glaucoma Glaucoma is a group of diseases involving the optic nerve. It involves loss of retinal ganglion cells in a specific pattern of optic neuropathy. Increased IOP is indicative of glaucoma. However there is no exact threshold of increased IOP that causes glaucoma.

42. Glaucoma Glaucoma: Open Angle is seen in 90% of glaucoma patients. Results in: Chronic obstruction of aqueous humor drainage Progressive course May not be associated with pain Risk Factors: Family hx, age, race,(african americans have increased incidence)DM & CAD

43. Glaucoma Glaucoma: Narrow angle, effects the other 10% of glaucoma pts. Acute obstruction caused by narrowing of the anterior chamber. Results in pupil dilation or lens edema Very Painful

45. Anatomical Facts related to eyes optic nerve lies on medial side of midsagittal plane of eye Optic nerve and extraocular muscle origins are tightly packed at the apex of the orbit Arterial blood supply to orbit and contents= ophthalmic artery (branch of internal carotid artery) The principal vein= superior ophthalmic Ciliary ganglion lies in posterior part of orbit, receiving preganglionic fibers through the oculomotor nerve Edinger-Westphal nucleus- when excited, it leads to miosis�opiods excite this and atropine blocks effects leading to mydriasis

46. Ophthalmic nerve- sensory, supplying lacrimal gland, conjunctiva, skin and mucous membrane of nose, skin of forehead 3 branches: lacrimal, frontal, nasociliary Motor nerves to extraocular muscles: 1.Oculomotor (3)- supplies iris (raises upper eyelids) and all ocular muscles except lateral rectus 2. Inferior rectus- rotates eye down 3. Inferior oblique- rotates eye up and out

47. Facial Nerve- (7) motor nerve- supplies orbicularis oculi muscle, responsible for blinking and lid squeezing. (can block this nerve at mastoid area but more complications with this so not commonly done)

48. Regional Anesthesia for the eye Retrobulbar Block (intracone) Peribulbar Block (extracone) Sub-Tenon Block Facial Nerve Block Topical Anesthesia

49. Retrobulbar Block INDICATIONS: -OCULOPLASTIC SURGERY -STRABISMUS -POSTERIOR CHAMBER PROCEDURES -ANTERIOR CHAMBER PROCEDURES -CORNEAL PROCEDURES -CATARACTS LANDMARKS: -INFEROLATERAL BORDER OF BONY ORBIT -PLANE OF IRIS -MIDSAGITTAL PLANE OF EYE

52. TECHNIQUES(transconjunctival or transcutaneous) Local anesthetic is injected behind the eye into the cone formed by extraocular muscles (see picture) Patient supine or sitting, looking straight ahead (primary gaze) Use fine needle or blunt 23-27 gauge needle Penetrates lower lid at the junction of the middle and lateral one-third of the orbit After aspiration, to ensure not intravascular, 2-5ml of local is injected and removed CHOICE OF LOCAL: Lidocaine-2% Bupivacaine-0.5% Ropivacaine Addition of epi (1:200,000 or 300,000) may reduce bleeding and prolongs block Do not use epi if patient has decreased blood supply to eye Can use just lidocaine if quick surgery but bupivacaine is better with epi if longer surgery

53. Techniques Continued�. So.. Place needle with local attached at the inferolateral border of bony orbit and direct it toward the apex of orbit, follow at 10 degree upward angle. A pop is felt as needle tip enters orbital muscle cone Aspirate and inject 3-5cc of local Do not introduce needle too posterior A successful block is accompanied by anesthesia, akinesia, and abolishment of oculocephalic reflex (a blocked eye does not move during head turning) IMPORTANT! Surgeon can use hyaluronidase (hydrolyzer of connective tissue polysaccharides) to enhance block and spread of local anesthetic. This allows block of facial nerve which innervates orbicularis oculi muscle

54. PERIBULBAR BLOCK In contrast to retrobulbar block, this block does not penetrate the cone formed by the extraocular muscles. Both techniques achieve akinesia of the eye equally well. Advantages over retro block are: less risk of eye pentration, optic nerve and artery, and less pain on injection. Disadvantages include: slower onset and increased likelihood of ecchymosis ( bruising)

55. TECHNIQUE Larger volume of Local needed Patient is supine and looking straight ahead Topical can be used first in the conjunctiva (check for allergies) topical can cause phacoemulsifications (lens disinegration) As eyelid is retracted, inferotemporal injection is given halfway between lateral canthus and lateral limbus. Needle is advanced under globe parallel to the orbital floor and when it passes the equator of the eye it is directed slightly medial (20�) and cephalad (10�).

56. Differences in Retro and Peri Blocks

57. FACIAL Nerve Block (7) Facial Nerve Block prevents squinting of the eyelids during surgery and allows placement of the lid speculum. Different techniques of facial nerve blocks : van Lint, Atkinson, and O� Brien. (see next slide for pics) Major complication of these particular blocks is subcutaneous hemorrhage. Nadbath�s technique is another block the blocks the facial nerve and this block runs in close proximity to vagus and glossopharyngeal nerves. (this block not recommended due to vocal cord paralysis, laryngospasm, dysphagia, and respiratory distress)

60. Sub-Tenon Block Tenon�s Fascia surrounds the globe and the extraocular muscles. Local anesthetic injected beneath it diffuses into the retrobulbar space. Blunt 25 or 19 gauge curved needle used After topical anesthesia, the conjunctiva is lifted along with the fascia with forceps A small nick is made with scissors and the needle is passed under the tenon�s fascia. This block is commonly used for cataract surgery 1.3 million people a year in USA have cataract surgery under regional anesthesia

62. Topical Anesthesia Less traumatic local anesthesia has evolved for cataract (anterior chamber) and glaucoma surgeries involving topical usage After instillation of anesthetic drops ( 0.5% proparacaine), an anesthetic gel is applied to inferior and superior conjunctival sacs. (0.5% tetracaine may also be used) Not good technique for posterior chamber (retinal detachment repair with buckle) This technique works best with a surgeon who is fast but gentle and does not need akinesia of eye.

63. Scleral buckle

64. This technique is used for reattachment of the retina or if a tear is in one location. Diabetes or Coats� disease ( in kids) are more susceptible to retinal detachment.

65. Contraindications and Complications Uncooperative patient Patient refusal Open eye injury due to increased IOP Chronic cough Parkinson�s disease Eye inflammation Retrobulbar block and elicit oculocardiac reflex Retrobulbar hemorrhage Hematoma Globe perforation Retinal detachment Blindness Systemic toxicity Total spinal Oculocardiac reflex Optic nerve trauma Extraocular muscle dysfunction (can be from local anesthetic or people with unhealthy musculature with increasing dosages)

66. Question 1: Case Presentation: A three year old male patient presents to SDS for scheduled strabismus surgery. He is healthy, all immunizations are up to date. NKDA. No hx of anesthesia complications for family or patient. Pt is induced without complications. Vitals are: BP:90/50 HR: 110 ST, RR: 20 Sat:98%. Surgery has begun: Suddenly your monitor alarms and his heart rate is 40bpm. (Besides OH X#@*) What do you do?

68. Question 2 All the following are measures/agents that can decrease IOP, EXCEPT: A. Mannitol B. Ketamine C. Volatile Agents D. NDMR

69. Answer #2 B: Ketamine: Rationale: Ketamine increases both ICP and IOP. Avoid in patients where IOP is a concern

70. Question: 3 All of the following are risk factors for cataracts, EXCEPT: A. Age B. Smoking C. CAD D. Corticosteroid use

71. Answer #3 C: CAD is a risk factor for glaucoma NOT for cataracts.

72. Question 4 What is the mechanism by which a patient can receive a total spinal after a retrobulbar block? Placing patient in trendelenberg position after spinal High local anesthetic dosage used Accidental access to CSF occurs secondary to perforation of meningeal sheaths that surround the optic nerve Patient coughs and moves after block is placed

73. Answer 3. Accidental cross into the CSF secondary to perforation of sheaths is the answer. If your patient starts to have trouble swallowing and begins to have apnea�duh�you have yourself a high total spinal. Yay!!!!

74. Question 5 How does hypercarbia alter intraocular pressure? Intraocular pressure increases with hypercarbia ( hypoventilation) Intraocular pressure decreases with hypocarbia (hyperventilation) No changes will occur with intraocular pressure Question 1 and 2 are both correct

75. Answer 4. Both 1 and 2 are both correct. Same thing happens with intracranial pressure in relation to increased or decreased CO2. (good way to remember that). Remember succinylcholine should not be used in open eye injuries or even most other eye surgeries in relation to the fact that it has the chance to increase IOP.