Advantages Day cases Good akinesia and Anesthesia Minimal effect on IOP Minimal equipment required
Disadvantages Not suitable for all patients Complications Skill of Surgeons/Anesthesiologists Unsuitable for certain types of surgery
Orbit – shape of irregular pyramid Base at front Axis points posterio- medially towards skullGlobe lies in anterior part of orbit- sits high and lateral
Four rectus muscles arise from the back of orbit Insert into the globe just forward of equator Form a cone - boundary between two compartments CENTRAL PERIPHERAL (retrobulbar) (peribulbar)
Within the cone Optic nerve Opthalmic artery & vein Ciliary ganglion Oculomotor nerves Sensory supply to orbit from opthalmic division Trigeminal nerve enters the orbit through superior orbital fissure
Comfort Assistant providing reassurance O2 saturation, ECG, BP monitoring Right angled screen providing O2
Intravascular injection Anaphylaxis Hemorrhage Subconjunctival edema Penetration / perforation of the globe Central spread (sub-arachnoid) Optic nerve atrophy
2001Guidelines (RCA & College Of Ophthalmologists) Trained staff Surgeons – topical / sub-conjunctival / sub-Tenon – without Anesthesiologist Anesthesiologist & iv access when retrobulbar / peribulbar Anesthesiologist in charge when sedation used
Indications: Patient refusal Children / learning difficulties / movement disorders Major / lengthy procedures Inability to lie still / flat Claustrophobic
Patients at extreme age Old – medication, confused, deaf, blind, with co-morbid like DM, CAD, HTN, COPD Young – congenital anomalies, temp. & fluid balance Opthalmic drugs Timolol – B-Blocker Phospholine iodide – anti-cholinesterase
Normally 10-20 mmHg Must be controlled when operating within the globe IOP impaired op. conditions expulsion of intra-ocular contents Mild IOP improved op. conditions
Careful with face mask No ketamine Laryngoscopy after completely paralyzed 4% Xylocaine topical anesthesia at vocal cord Head up tilt Monitoring: ECG, oximeter, capnograph and peripheral nerve stimulator if available
Continue volatile agent until spontaneous respiration is resumed after reversal Anti-emetic may be administered No food/drink for 3 hours to reduce the possibility of aspiration of gastric contents★ If no muscle relaxants and patient breathes spontaneously, the depth of anesthesia must be increased to prevent coughing or straining against the tube.
Avoid nitrous in vitreoretinal surgery Bubbles of sulphurhexafluoride (SF3) Emergence without coughing Deep extubation Lignocaine on cords Bolus lignocaine/ propofol beforehand
Traction on EOM may cause sudden and profound bradycardia via oculocardiac reflex mediated by CN X Occasionally seen during other forms of eye surgery e.g. retinal detachment
Prevention Moderated by LA (abolish afferent arc) Avoid hypoxia/hypercapnia (sensitizes the reflex) Prophylactic anticholinergic ★ esp in children Management STOP stimuli at once Ensure adequate ventilation Ensure sufficient anesthetic depth If needed, atropine 0.02 mg/kg IV
Is atropine useful? Controversial 0.4 mg IM as a premedicant has no vagolytic effect after 60 min and is of no value in preventing or treating OCR 0.4 mg IV is effective for 30 minutes in preventing bradycardia associated with the OCR Doses >0.5 mg IV can cause tachycardia★
Examination in children can often be provided satisfactorily via a face mask If the naso-lacrimal duct is to be irrigated Intubation or Positioning the patient with a pillow under the shoulders Ketamine can also be used but pre-medication with atropine is essential to prevent laryngospasm caused by excessive secretions.
If sedation is required Midazolam (0.5 -1 mg) with Fentanyl 25 – 50 mg or Propofol 20 mg. Peribulbar block is advisable when axial length is less than 26mm and patient can lie flat & still. Haelan (Sodium Hyaluronate) is injected at the time of incision to maintain the shape of anterior chamber and controls the vitreous bulge.
Cataract Surgery can be performed under Regional Anesthesia without discontinuing anticoagulant therapy (Prothrombin Time 1.5 times control).