Anaesthesia implications during intraocular procedures

1. INTRAOCULAR PROCEDURES
AND IT’S ANAESTHETIC
IMPLICATIONS
PRESENTER: DR SAIKUMAR C PATIL
MODERATOR: DR SARAYU R
ASSISTANT PROFESSOR

2. Nerve supply of orbit
• Optic nerve (CN II) carries the neural signals from the retina.
• MOTOR SUPPLY:
• Oculomotor nerve (CN III): motor supply to all EOM’s except LR and SO
• Trochlear nerve (CN IV): motor to lateral rectus[LR6]
• Abducens nerve (CN VI): motor to superior oblique[SO4]
• A branch of the oculomotor nerve supplies a motor root to the ciliary ganglion, which in turn supplies the sphincter of the
pupil and the ciliary muscle.
• SENSORY SUPPLY:
• Touch and pain sensations are carried via the trigeminal nerve (CN V).
• Sensation to the upper lid is via the frontal branch of the ophthalmic nerve (CN V1)
• Sensation to the lower lid is via the maxillary nerve (CN V2).
• The nasociliary branch of the ophthalmic nerve sends sensory fibers to the medial canthus, lacrimal sac, and ciliary ganglion.
• The ciliary ganglion provides sensory innervation to the cornea, iris, and ciliary body

3. Open-eye surgical procedures.
• Cataract extraction
• Corneal laceration repair
• Corneal transplant (penetrating keratoplasty)
• Peripheral iridectomy
• Removal of foreign body
• Ruptured globe repair
• Secondary intraocular lens implantation
• Trabeculectomy (and other filtering procedures)
• Vitrectomy (anterior and posterior)
• Wound leak repair

4. PREANAESTHESTIC EVALUATION
• A thorough history of the patient and physical examination
• Testing should be based on the results of the history and physical
examination
• whether to continue or suspend antithrombotic therapy prior to surgery is
a dilemma
• Elderly individuals on anti coagulant therapy are at higher risk for
perioperative hemorrhagic events, including retrobulbar hemorrhage,
circumorbital hematoma, intravitreous bleeding, and hyphema.
• Although prior discontinuation of antithrombotic agents may diminish the
potential for perioperative ocular bleeding, such strategy may increase the
risk of adverse events like myocardial ischemia, infarction, cerebrovascular
accident, and deep venous thrombosis.

5. PREANAESTHESTIC EVALUATION
• Coronary artery disease patients with drug-eluting stents: bare-metal stents are
susceptible to in-stent restenosis and drug-eluting stents are more vulnerable to
stent thrombosis.
• Patients with drug-eluting stents are typically on dual antiplatelet therapy with
aspirin and clopidogrel, which should be continued perioperatively.
• Elective surgery should be delayed for at least 4 to 6 weeks after placement of a
bare metal stent and for 6 months after drug-eluting stent placement.
• Hypertension is encountered in the majority of geriatric patients. Those with
poorly controlled blood pressure should not receive dilating eye drops, such as
phenylephrine.
• Cough, orthopnea, and restlessness are the most common precipitators of
excessive motion.
• Propofol sedation for eye block is associated with sneezing.
• Midazolam, fentanyl, and alfentanil given prior to propofol abate the sneeze
reflex

6. Requirements for Ophthalmic Surgeries
• Saftey
• Akinesia
• Analgesia
• Minimal bleeding
• Avoidence or obtundation of occulo cardiac reflex
• Control of IOP
• Awareness of drug interactions
• Smooth emergence devoid of vomiting, retching and coughing.

7. ANAESTHETIC OPTIONS:
• General anesthesia
• Retrobulbar (intraconal) block,
• Peribulbar (extraconal) anesthesia,
• Sub-Tenon block,
• Topical anesthesia,
• Intracameral injection

8. GENERAL ANAESTHESIA
• PREMEDICATION:
• An effective antiemetic should be used to decrease PONV. Eg-
Ondansetron
• Benzodiazepines are given.

9. GENERAL ANAESTHESIA
• Pretreatment regimens to control the sympathetic response to
tracheal intubation:
• i.v. Lidocaine (1.5 mg/kg)
• i.v. Remifentanil(0.5 to 0.1 µg/kg)
• i.v. Fentanyl (1 to 3 µg/kg) 3 to 5 minutes before induction.
• i.v alfentanil (20 µg/kg)
• Oral clonidine (5 µg/kg) 2 hours before induction

10. GENERAL ANAESTHESIA
• INDUCTION
• The choice of induction technique for eye surgery usually depends
more on
• the patient’s medical problems
• the patient’s eye disease
• the type of surgery contemplated.

11. GENERAL ANAESTHESIA
• Intravenous agents: Propofol, Thiopental and Etomidate.
• Volatile Agents: can be used, minimal PONV.
• Coughing during intubation: avoided by a deep level of anesthesia
and profound paralysis.
• The IOP response: to laryngoscopy and endotracheal intubation can
be blunted.
• LMA: can also be used. Less changes in IOP.

12. GENERAL ANAESTHESIA
• AIRWAY MANAGEMENT
• Intraocular surgery requires a still eye with low intraocular pressure
and the airway is best managed by intubation with paralysis and
controlled ventilation.
• Access to the airway will be restricted during the surgery so it is
important to secure the tracheal tube firmly.
• A preformed south facing RAE tube is ideal, but this may be too long
in neonates; a reinforced flexible tracheal tube (ETT) may be
preferable in this situation.

13. GENERAL ANAESTHESIA
• RELAXATION
• A nondepolarising muscle relaxant is used instead of succinylcholine
because the latter increases intraocular pressure.
• However, the rise in IOP is small by succinylcholine than the fall
caused by intravenous induction agent, and also considering risk of
aspiration succinylcholine can be used in an emergency case.

14. GENERAL ANAESTHESIA
• MAINTENANCE
• Where halothane is used there is an increased risk of dysrhythmias,
particularly where eye preparations containing atropine or adrenaline
are used, and in the presence of hypercapnia.
• Isoflurane or sevoflurane may be preferable.
• Total intravenous anaesthesia (TIVA) with propofol has advantages in
reducing the risk of postoperative nausea and vomiting (PONV) since
propofol has anti-emetic effects.
• Remifentanil can reduce volatile requirements.

15. GENERAL ANAESTHESIA
• USE OF NITROUS OXIDE
• The use of nitrous oxide in eye surgery is limited by two factors.
• Increase the risk of PONV, and in ophthalmic procedures there is a
high incidence of PONV
• Secondly, nitrous oxide diffuses from the blood into gas filled spaces
in the body.
• It should be avoided in vitreoretinal detachment surgery where
intraocular gas bubbles of sulphur hexachloride or perfluropropane
are introduced into the eye to tamponade detached surfaces.

16. GENERAL ANAESTHESIA
• Prevention Intraocular gas expansion
• discontinue nitrous 15-20 mins prior to injection.
• Avoid nitrous oxide 5 days after air and 10 days after sulfur
hexachloride injection.
• In case of perfluoropropane avoid nitrous for atleast a month, or until
the bubble is resorbed.

17. GENERAL ANAESTHESIA
• EXTUBATION & EMERGENCE
• A smooth emergence from general anesthesia
• Deep level of anesthesia.
• Intravenous lidocaine (1.5 mg/kg) prior to extubation.
• Severe postoperative pain is unusual.

18. REGIONAL ANAESTHESIA
• Retrobulbar block (intraconal block)
• Neutral position, 25G, 1 inches needle
• 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

19. REGIONAL ANAESTHESIA
• Peribultbar 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.
• Patients lies in supine + neutral position, 24-26G needle
• Point at lateral1/3 and the medial 2/3 of the inferior orbital edge
Directed to the apex of the orbit
• Deposited at equator of globe

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

21. COMPLICATIONS OF NEEDLE BASED
OPHTHALMIC ANAESTHESIA
• Stimulation of oculocardia reflex arc
• Superficial hemorrhage → circumorbital hematoma
• Retrobulbar hemorrhage +/- retinal perfusion compramise → loss of vision.
• Globe penetration +/- intraocular injection → retinal detachment, loss of vision
• Trauma to optic nerve or orbital cranial nerves
• Optic nerve sheath injection → orbital epidural anesthesia
• Extraoccular mussle injury, leading to post-op strabismus & diplopia
• Central retinal artery occlusion
• Intra arterial convulsions → convlsions
• Inadvertent brainstem anaesthesia

22. Concerns with various ocular procedures
PROCEDURES CONCERNS
STRBISMUS REPAIR OCCULO CARDIAC REFLEX
OCCULO GASTRIC REFLEX
FORCED DUCTION TESTING
MALIGNANT HYPERTHERMIA
INTRAOCCULAR SURGERIES PROPER CONTROL OF IOP
AKINESIA
DRUG INTERACTIONS
ASSOCIATED SYSTEMIC DISEASES
RETINAL DETACHMENT SURGERIES NITROUS OXIDE INTERACTION WITH AIR: SULFUR
HEXAFLUORIDE, PERFLURO CARBON GAS BUBBLE
VENOUS AIR EMBOLISM
OCCULO CARDIAC REFLEX
PROPER CONTROL OF IOP

23. OCULOCARDIAC REFLEX
• First described by Aschner and Dagnini in 1908.
• Also known as the Trigeminovagal reflex.
• PRESENTATION: Traction on the extraocular muscles or pressure on the globe causes
bradycardia, atrioventricular block, ventricular ectopy, or asystole.
• In particular, it is seen with traction on the medial rectus muscle, but it can occur with stimulation
of any of the orbital contents, including the periosteum.
• The response fatigues with repeated stimulation.
• Reflex may be seen more often with procedures performed with topical anesthesia, and it occurs
commonly in pediatric patients undergoing strabismus surgery

24. OCULOCARDIAC REFLEX
• Afferent of the reflex limb: arises from the ophthalmic division of the trigeminal nerve →
continues to the Gasserian ganglion and the sensory nucleus of the trigeminal nerve near the
fourth ventricle. Here, the afferent limb synapses with the motor nucleus of the vagus nerve.
• Efferent impulses travel to the heart via the vagus nerve leading to decreases in both heart rate
and contractility of the heart.
• The response is exacerbated by:
• Hypercapnia
• Hypoxemia
• Inadequate depth of anesthesia

25. OCULOCARDIAC REFLEX
• MANAGEMENT:
• In the event of arrhythmia, the anesthesiologist should first ask the surgeon to
stop manipulations.
• Any condition that may exaggerate the reflex should be assessed and treated.
• If significant bradycardia persists or recurs, intravenous glycopyrrolate or
atropine can be given.
• Rarely, epinepherine is given to treat severe bradycardia or asystole.

26. OCULORESPIRATORY REFLEX
• 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.

27. 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

28. SYSTEMIC SIDE EFFECTS OF OPHTHALMIC
DRUGS
DRUG MAO USES SIDE EFFECTS
Acetylcholine Cholinergic agonist Meiosis Bradycardia, bronchospasm,
hypotension
Acetazolamide (PO, IV, IM) Carbonic anhydrase inhibitor Decrease IOP, Glaucoma Confusion, drowsiness,
hypokalemia, hyponatremia,
metabolic acidosis, abnormal
hepatic function tests,
polyuria, renal failure
Anti-VEGF, e.g.,
ranibizumab, aflibercept
Inhibits vascular endothelial
growth factor
Inhibits neovascularization Conjunctival hemorrhage, eye
pain, endophthalmitis, uveitis,
stroke (in high-risk patients)
Atropine Anticholinergic Mydriasis Dry mouth, dry skin, fever,
agitation (central
anticholinergic syndrome)
Cyclopentolate Anticholinergic Mydriasis, cycloplegia Central anticholinergic
syndrome (see atropine)

29. DRUG MAO USES SIDE EFFECTS
Echothiopate Irreversible cholinesterase
inhibitor
Glaucoma Total body inhibition of
plasma cholinesterase
Prolongs effects of
succinylcholine
Epinephrine α-, β agonist Mydriasis, decrease IOP Hypertension, tachycardia,
ventricular arrhythmias
Mannitol Osmotic diuretic Decrease IOP Initial increase in circulating
blood volume; congestive
heart failure in patients with
poor ventricular function
Phenylephrine α Adrenergic agonist Mydriasis, vasoconstriction Hypertension
Pilocarpine Cholinergic Constrict pupil Bradycardia, bronchospasm
Scopolamine Anticholinergic Mydriasis, cycloplegia Central anticholinergic
syndrome (see atropine)
Timolol β1 and β2 antagonist Glaucoma Bradycardia, bronchospasm,
exacerbate congestive heart
failure

30. OPHTHALMIC EMERGENCIES
• TRUE EMERGENCIES: require immediate intervention to prevent loss of sight
• Ocular burns
• Central retinal artery occlusion
• SEMIURGENT CONDITIONS
• Ocular tumors,
• Blowout fractures of the orbit,
• Congenital cataract,
• Chronic retinal detachment.
• URGENT SITUATIONS
• Open globe injuries
• Endophthalmitis
• Acute narrow-angle glaucoma
• Acute retinal detachment
• Corneal foreign body
• Lid laceration.

31. OPEN GLOBE AND FULL STOMACH
• Emergent or urgent surgery is required.
• Challenges for anaesthesiologist:
• Pulmonary aspiration of stomach contents
• Acute changes in IOP.
• Factors that may increase IOP during induction of anesthesia
• Crying,
• Coughing,
• Bucking,
• Straining particularly during suboptimal intubating conditions.
• Additional factors implicated in increasing IOP are mask pressure, hypercarbia, hypoxia, and
elevated BP

32. OPEN GLOBE AND FULL STOMACH
• Succinylcholine, used as part of a rapid-sequence induction of anesthesia to permit rapid
intubation and airway protection, causes a modest increase in IOP of 8 to 10 mm Hg.
• There are also no claims for such injury since 2000 in the ASA Closed Claims Project that is
designed to detect patterns of injury during anesthesia.
• Based on the current evidence, succinylcholine may be used to facilitate endotracheal intubation
in open eye injuries, despite its effect on IOP.
• An alternative option for those at risk for aspiration is to use higher dose rocuronium (0.9-1.2
mg/kg) and to reverse neuromuscular blockade with sugammadex.

33. 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.

34. 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.

35. 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.

36. REFERENCES:
• Miller’s ANAESTHESIA, 9th edition
• Clinical anaesthesia, Paul G Barash, 8th edition
• Morgan AndMikhail’s Clinical ANAESTHESIOLOGY, 6th edition

37. THANK YOU