Even patients with serious medical problems can often undergo eye surgery under regional anesthesia provided their medical condition(s) are well controlled, they can lie flat without moving for the length of the procedure, and they are able to communicate with their ophthalmologist and anesthesia staff.
True ophthalmic emergencies are rare. Central retinal artery occlusion and chemical burns require immediate treatment. Uncontrolled glaucoma, ruptured globe and threatened macula detachment are urgent conditions but can usually be delayed long enough to allow appropriate management of the patient's medical condition.
Cataract and other eye operations under regional anesthesia have a low risk of serious perioperative complications. Regional anesthesia greatly reduces the risk of pain, nausea, and vomiting occurring in the immediate post operative period.
General anesthesia increases the risk of minor complications (eg, nausea and vomiting) and in some instances (eg, patients with valvular heart disease or pulmonary hypertension) major perioperative complications. During general anesthesia, akinesis and hemodynamic stability must be maintained to avoid eye damage. A smooth emergence and control of pain and postoperative nausea and vomiting are important.
Safe performance of regional orbital blocks requires knowledge of orbital anatomy, instruction by a qualified practitioner, knowledge of possible complications, adequate patient monitoring, and immediate availability of resuscitation equipment. Patients should be mildly sedated but cooperative during needle placement for orbital blocks. Knowledge or estimation of the axial length of the eye before performing retrobulbar block may reduce the risk of globe perforation. Eyes 26 mm or longer in length, with previous scleral buckles, and with enophthalmos have greater potential for injury from retrobulbar blocks. Needles longer than 32 mm in the inferolateral orbit and longer than 25 mm in the medial orbit increase the risk of serious complications. Inserting a retrobulbar or peribulbar block needle below the lateral canthus ("modified" inferolateral insertion point) instead of the junction of the medial and lateral third of the lower eyelid may reduce extraocular muscle (EOMs) injury.
The oculocardiac reflex (OCR) can occur when pressure is applied to the globe or traction applied to the EOMs. It can present as sinus bradycardia, atrioventricular block, or asystole. OCR is more common during general than regional anesthesia and more common in children than adults. Prompt cessation of the inciting maneuver sometimes is sufficient therapy. Although it is often a fatigable reflex, OCR may require treatment with glycopyrrolate or atropine if severe or persistent. The reflex can often be prevented or abolished with an orbital block.
Coughing or "bucking" increases intraocular pressure (IOP) and the risk of intraoperative eye damage. The increase in IOP from laryngoscopy and intubation can be blunted by sufficient doses of propofol, a narcotic, lidocaine, and a muscle relaxant. If a rapid-sequence induction is considered with globe injury, the risk of difficulty in securing the airway and the viability of the eye should first be assessed. Rocuronium (0.6-1.2 mg/kg) is often a good choice for muscle relaxant if the intubation is anticipated to be easy. If succinylcholine is deemed necessary, a dose ...