1. The document discusses anaesthesia considerations for various ophthalmic surgeries including cataract surgery, glaucoma surgery, and procedures in children. 2. Key goals of anaesthesia for eye surgery are to have an immobile eye, stable intraocular pressure, minimize bleeding and nausea/vomiting, and avoid complications like the oculo-cardiac reflex. 3. Different procedures and patient conditions require specific anaesthetic approaches. For example, glaucoma patients may require mannitol or catheterization due to eye drop medications, while gas injections require avoiding nitrous oxide due to gas bubble expansion.

1. Anaesthesia for Eye-surgery Dr.Shailendra.V.L. Specialist in Anaesthesia Al Bukariya general hospital Saudi Arabia.

2. Introduction Technological improvements Improved surgical techniques Improved techniques in anaesthesia Better understanding of the physiology

3. Ophthalmic Surgery Extra ocular surgery- strabismus correction Intra ocular surgery- cataract with IOL Mixed - drainage operations for glaucoma

4. 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

5. Physiology of intra ocular pressure INTRA-OCULAR PRESSURE DETERMINANTS: Factors exerting outward pressure Factors exerting inward pressure

6. Intra-ocular pressure Aqueous humour Vitreous humour Blood within the eye Scleral compliance Extra-ocular muscle tone

7. 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 Fontana  drains through Episleral venous system

8. Drugs acting on AH mechanics  production: Acetozolamide (carbonic anhydrase inhibitor) Beta blockers Improve drainage: Miotics (by contracting ciliary muscle) Mydriatics affects drainage

9. 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

10. Vitreous Humour Fine unstable gel consisting of water & fine supporting structure Volume & pressure reduced by Mannitol which is a dehydrating agent & there by ↓ IOP

11. 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

12. Pharmacological modifications of IOP Pre anaesthetic Medication: IV diazepam & midazolam ↓ IOP Parental atropine has no effect on IOP Intravenous anaesthetics: Only ketamine ↑ IOP All other agents ↓ IOP

13. Pharmacological modifications of IOP Inhalational agents effect IOP by: Central action on mid-brain Alteration of aqueous humour ↓ extra-ocular muscle tone Dose dependent reduction in IOP

14. 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

15. Oculo-cardiac reflex Trigemino-vagal reflex Bradycardia, nodal rhythm, ectopic beats, ventricular fibrillation, asystole Eyeball pressure, traction of extra-ocular muscles, orbital haematoma, ocular trauma & eye pain, eyelid traction Can occur even from enucleated orbit

16. Oculo cardiac reflex Afferent pathway Efferent pathway   Short & long ciliary nerves Nucleus of vagus   Ciliary ganglion Cardiac branches via  ophthalmic  division of trigeminal nerve Bradycardia  Trigeminal sensory nucleus

17. Treatment of OCR Ask surgeon to stop all the manipulations Intravenous Atropine 15 micro grams / Kg or intravenous Glycopyrrolate 7.5 micro grams / Kg

18. 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 & arrhythmias Timolol (B-blocker) causes bradycardia, hypotension & exacerbation of asthma Phospoline iodide is a lone acting anti-cholinesterase used in glaucoma prolongs suxamethonium induced muscle relaxation

19. Anaesthetic management of elective intra ocular surgery Goals of general anaesthesia: Immobile eye Stable IOP Minimize bleeding Avoidance of Oculo-cardiac reflex Smooth induction Smooth emergence Minimal post-operative nausea & vomiting

20. Common Ocular surgeries Cataract surgeries Lid surgeries Conjuctival surgeries Strabismus surgeries Penetrating eye injuries Vitreous surgeries Retinal surgeries Laser surgeries

21. Anaesthetic management of elective intra-ocular surgery Pre-medication: use of anxiolytics Induction: Thiopentone + Suxamethonium Intubation: Smooth laryngoscopy & intubation Maintenance: O2 + N20 + Isoflurane/Halothane IPPV with Non-depolarizing muscle relaxant Reversal: Neostigmine + Atropine , extubate in deeper planes Problems encountered: Dark room Face inaccessible

22. 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

23. 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

24. Anaesthesia for special ocular procedures Retinal detachment surgery: Oculo-cardiac reflex commonly observed Essentially extra-ocular surgery Synthetic silicone strap used to produce scleral indentation

25. 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

26. Anaesthesia for special ocular procedures Vitrectomy: Closed intra-ocular procedure Surgeon controls IOP manometrically by water tight infusion

27. Ophthalmic procedures in children Naso-lacrimal duct probing / syringing Examination under anaesthesia Intra-ocular pressure measurement Strabismus correction

28. Naso-lacrimal duct probing Done to open up the duct Trachea to be intubated & throat packed to prevent the fluid entering trachea

29. Examination under GA Very common procedure Done to examine in detail the eyes Total intra-venous anaesthesia technique should be used as the procedure is short

30. 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

31. Strabismus surgery Incidence of OCR very high Careful monitoring Should be anticipated and treated with Atropine / Glycopyrrolate Avoidance of PONV by the use of Ondansetrone

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