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Anesthesia for Eye surgeries
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1
Anaesthesia for Eye-surgery
Dr.Shailendra.V.L.Specialist in AnaesthesiaAl Bukariya general hospitalSaudi Arabia.
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Introduction
Technological improvements Improved surgical techniquesImproved techniques in anaesthesia Better understanding of the
physiology
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Ophthalmic Surgery
Extra ocular surgery- strabismus correction
Intra ocular surgery- cataract with IOLMixed - drainage operations for glaucoma
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Anaesthesia requirements for ophthalmic surgery
Immobile eye Uncongested eye Intra ocular pressure:
- to minimize the danger of expulsion of intra ocular contents
Smooth recovery Avoidance of PONV
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Physiology of intra ocular pressure
INTRA-OCULAR PRESSURE DETERMINANTS:
Factors exerting outward pressure Factors exerting inward pressure
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Intra-ocular pressure
Aqueous humourVitreous humourBlood within the eyeScleral complianceExtra-ocular muscle tone
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Aqueous humour dynamics
Ultrafiltration of plasma by ciliary epithelium
Formation of A H in ciliary process
A H circulate around Iris via pupil
Anterior chamber
Canal of Schelmn
Trabecular spaces of Fontanadrains through
Episleral venous system
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Drugs acting on AH mechanics
production:Acetozolamide (carbonic anhydrase
inhibitor)Beta blockers
Improve drainage:Miotics (by contracting ciliary muscle)Mydriatics affects drainage
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Choroidal blood volume effecting AH mechanics
Systemic blood pressure: Choroidal capillaries auto-regulatory
function ↑ in Blood pressure causes transient ↑in IOP
Venous pressure: ↑in CVP causes acute ↑in IOP Coughing/ vomiting/ valsalva/ straining on
tube all ↑ IOP ↑PaCO2 causes ↑ IOP by choroidal
vasodilatation
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Vitreous Humour
Fine unstable gel consisting of water & fine supporting structure
Volume & pressure reduced by Mannitol which is a dehydrating agent & there by ↓ IOP
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Extra-ocular muscle tone
Tone controlled by the mid-brain
GA ↓ muscle tone & there by ↓ IOP
Gentle, constant pressure on the eye promotes aqueous humour flow & ↓ IOP
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Pharmacological modifications of IOP
Pre anaesthetic Medication:IV diazepam & midazolam ↓ IOPParental atropine has no effect on IOP
Intravenous anaesthetics:Only ketamine ↑ IOPAll other agents ↓ IOP
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Pharmacological modifications of IOP
Inhalational agents effect IOP by:Central action on mid-brainAlteration of aqueous humour↓ extra-ocular muscle tone
Dose dependent reduction in IOP
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Pharmacological modifications of IOP
Neuro-muscular blockers:Succinylcholine- ↑ IOP by 10 mmHg
by 1 minute & lasts for 10 minutes↑ IOP due to tonic action of drug on
Felderstruktur striated extra0ocular muscle
Laryngoscopy & Intubation: ↑ IOP
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Oculo-cardiac reflex
Trigemino-vagal reflexBradycardia, nodal rhythm, ectopic beats,
ventricular fibrillation, asystoleEyeball pressure, traction of extra-ocular
muscles, orbital haematoma, ocular trauma & eye pain, eyelid traction
Can occur even from enucleated orbit
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Oculo cardiac reflexAfferent pathway Efferent pathway
Short & long ciliary nerves Nucleus of vagus
Ciliary ganglion Cardiac branches
via ophthalmic division of trigeminal nerve Bradycardia
Trigeminal sensory nucleus
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Treatment of OCR
Ask surgeon to stop all the manipulations
Intravenous Atropine 15 micro grams / Kg or intravenous Glycopyrrolate 7.5 micro grams / Kg
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Systemic effects of ophthalmic medications
Eye drops are readily absorbed through hyperemic, incised conjunctiva causing systemic effects
Phenyleohrine(2.5%) cause hypertension, arrhythmia and headache
Adrenaline(2%) cause hypertension & arrhythmiasTimolol (B-blocker) causes bradycardia,
hypotension & exacerbation of asthmaPhospoline iodide is a lone acting anti-
cholinesterase used in glaucoma prolongs suxamethonium induced muscle relaxation
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Anaesthetic management of elective intra ocular surgery
Goals of general anaesthesia: Immobile eyeStable IOPMinimize bleedingAvoidance of Oculo-cardiac reflexSmooth inductionSmooth emergenceMinimal post-operative nausea & vomiting
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Common Ocular surgeries
Cataract surgeries Lid surgeries Conjuctival surgeries Strabismus surgeries Penetrating eye injuries Vitreous surgeries Retinal surgeries Laser surgeries
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Anaesthetic management of elective intra-ocular surgery
Pre-medication: use of anxiolytics Induction: Thiopentone + Suxamethonium Intubation: Smooth laryngoscopy & intubationMaintenance: O2 + N20 + Isoflurane/Halothane
IPPV with Non-depolarizing muscle relaxantReversal: Neostigmine + Atropine , extubate in
deeper planes
Problems encountered: Dark room
Face inaccessible
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Anaesthesia for perforating eye injury Problems: Full stomach patient
Perforated eye Plan: Preoxygenation Induction: Thiopentone + Atracurium
Sellick’s maneuver Smooth laryngoscopy & intubation
Controlled ventilation Smooth extubation
Use of Ondansetron to prevent PONV
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Anaesthesia for special ocular surgeries
Glaucoma:Anti-cholinesterase eye drops used in
treatment can potentiate effects of succinylcholine precipitating bradycardia & arrhythmias
To ↓ IOP 20% mannitol is used, hence it is better to catheterize these patients
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Anaesthesia for special ocular procedures
Retinal detachment surgery:Oculo-cardiac reflex commonly observedEssentially extra-ocular surgerySynthetic silicone strap used to produce
scleral indentation
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Anaesthesia for special ocular surgeries
Intra-vitreous gas injection:Intra-vitreous injection of inert gas of
low diffusibility such as Sulphar hexafluride (SF6) or Carbon octofluride (C3F6)
Gas is absorbed over 10 days and the bubble keeps the sclera intact
N20 must be avoided as the bubble size increases upto three times
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Anaesthesia for special ocular procedures
Vitrectomy:Closed intra-ocular procedureSurgeon controls IOP manometrically
by water tight infusion
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Ophthalmic procedures in children
Naso-lacrimal duct probing / syringingExamination under anaesthesiaIntra-ocular pressure measurementStrabismus correction
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Naso-lacrimal duct probing
Done to open up the ductTrachea to be intubated & throat packed
to prevent the fluid entering trachea
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Examination under GA
Very common procedureDone to examine in detail the eyesTotal intra-venous anaesthesia technique
should be used as the procedure is short
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IOP measurement in children
General anaesthesia with ketamine must be avoided as IOP will be raised with ketamine
General anaesthesia with non-depolarizing relaxants preferred
It is advisable to wait for 10 minutes to take measurements after intubation for the IOP to stabilize
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Strabismus surgery
Incidence of OCR very highCareful monitoring Should be anticipated and treated with
Atropine / GlycopyrrolateAvoidance of PONV by the use of
Ondansetrone