Anesthesiology

Cataract Surgery

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What the Anesthesiologist Should Know before the Operative Procedure

Cataract surgery is considered to be minimally invasive; however, patients are typically elderly or amongst the eldest elderly. They frequently present with a host of concomitant medical issues that may have impact upon perioperative anesthesia management. Key issues associated with cataract surgery include intraocular pressure, the oculocardiac reflex, the systemic effects of ophthalmic medications, preoperative evaluation, anticoagulant status, ability to remain relatively still during surgery in the supine position, and more.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

There is rarely any pressing urgency to perform this type of surgical procedure. Most cataract operations are accomplished on an elective basis in ambulatory surgical facilities. Medical exigencies should take priority.

2. Preoperative evaluation

Cataract surgery patients are "high risk" patients having "low risk" surgery. Preoperative evaluation needs to focus on ensuring that medical status is optimized to a level of acceptable risk. It is not uncommon to find patients sufficiently ill to require postponement of elective surgery in order to address urgent medical needs. Preoperative evaluation of cardiovascular, pulmonary, neuromuscular, and endocrine status is key.

Medically unstable conditions warranting further evaluation include: Unstable or atypical angina, decompensated congestive heart failure, significant dysrhythmia, severe valvulopathy, malignant hypertension, active upper respiratory infection, decompensated COPD, Pickwickian obstructive sleep apnea, and uncontrolled diabetes.

Delaying surgery may be indicated if: New onset of angina or change in characteristics of patient's angina, angina at rest, dyspnea, inability to lie flat, new onset atrial fibrilation, supraventricular dysrhythmia with uncontrolled heart rate, ventricular dysrhythmia, complete heart block, recent/frequent ICD discharge, poor peripheral oxygen saturation, moderate active cough, orthopnea, and severe hyper- or hypoglycemia

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system:

Acute/unstable conditions

Cataract surgery per se does not predispose patients to cardiovascular complications; however, eye surgery patients tend to be at high risk for having preexisting cardiovascular disease. Acute issues such as new onset or unstable or atypical angina, angina at rest, decompensated congestive heart failure, significant dysrhythmia, tachydysrhythmias, severe valvulopathy, and malignant hypertension typically require greater priority for intervention than the elective surgical procedure. Postpone surgery.

Baseline coronary artery disease or cardiac dysfunction

Ensure that there have not been any recent changes in baseline cardiac status. Ideally, obtain recent evaluation of pacemaker and/or ICD function.

c. Pulmonary:

Active URI, COPD, reactive airway disease (asthma), symptomatic postnasal drip

Cataract surgery generally requires that the patient remain in supine position, relatively quiescent, for the duration of the procedure. If the patient cannot do so, whether due to severe cough, uncontrolled emphysema / COPD, or reactive airway disease, the risk for untoward visual outcome increases. Consider antitussives, bronchodilators, or nasal decongestants. Consider postponing elective surgery.

Obstructive sleep apnea

Assess patient's ability to remain supine without developing airway obstruction.

d. Renal-GI:

Gastrointestinal:

Inquire about history of postoperative nausea or vomiting. Consider prophylactic antiemetic for the at-risk patient.

GERD: Determine if treated and asymptomatic or if persists.

e. Neurologic:

Parkinson's disease

Mild tremor, particularly of the upper or lower extremities may not have impact on surgery. Moderate head tremor, however, may render cataract surgery via monitored anesthesia care untenable. Assure that patients with Parkinson's disease continue their medicines through the day of surgery.

Dementia

Assess patient's ability to remain relatively still during surgery. Assure continuation of medications. Consider general anesthesia if at high risk for gross movement during surgery.

f. Endocrine:

Diabetes: Determine adequacy of glucose control.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Musculoskeletal

Arthritis and lower back pain may limit the patient's ability to remain in supine position with little gross movement. Assure medications are continued the morning of surgery. Assess ability to position properly.

Ophthalmologic

Patients with a history of myopia (near-sightedness) may have a globe that is larger than is typical, rendering the eye at greater risk for unintentional penetration by a block needle. In addition to occupying more space, larger eyes tend to be thinner and more readily injured. Prior surgery with placement of a scleral buckle also distorts the globe's shape, increasing risk. Additionally, an enophthalmic (deeply recessed) globe is at enhanced risk of needle injury.

Ophthalmologic

Assess quality of vision in the nonoperative eye. Consider short-acting local anesthetic, general anesthesia, or topical anesthesia for the monocular patient having surgery on their sighted eye.

4. What are the patient's medications and how should they be managed in the perioperative period?

Most medications should be continued on the day of surgery. Oral hypoglycemic agents may be omitted. Intermediate, combination, and long-acting insulin should be reduced while regular insulin should not be administered on the morning of surgery. Some herbals and supplements may interact or augment anesthetic sedation and may increase the propensity towards bleeding, so consider discontinuing these one to two weeks prior to surgery.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Anticoagulant medications: Many cataract surgery patients have prescribed antiplatelet and/or anticoagulant medications due to coronary or vascular disease. Clopidogrel, coumadin, or aspirin may predispose towards perioperative bleeding, including choroidal hemorrhage, hyphema, circumorbital bleeding, and retrobulbar hemorrhage. These agents have been traditionally discontinued prior to elective cataract surgery. Unfortunately, withholding such medications can place patients at risk for coronary hypoperfusion, myocardial ischemia, thrombosis of drug-eluting stents, cerebrovascular accident, and peripheral deep venous thrombosis. Recent investigations suggest that surgery and regional anesthesia can be performed safely without discontinuation of said medications. Large-scale multicenter studies of cataract patients have not definitively proven the benefit of maintaining or discontinuing these agents.

Topical ophthalmic medications: Topical ophthalmic drops can be absorbed into the systemic circulation directly through the conjunctiva or, more likely, via drainage through the nasolacrimal duct onto the nasal mucosa. For example, nonselective beta-adrenergic blocking agents for treatment of concomitant glaucoma may produce severe bradydysrhythmia or exacerbate bronchospastic symptoms.

Echothiophate (phospholine iodide), an anticholinesterase once commonly prescribed for management of glaucoma, can profoundly interfere with metabolism of succinylcholine, resulting in prolonged neuromuscular paralysis following a single dose of succinylcholine. Normal pseudocholinesterase activity may not return for over a month after discontinuation of echothiophate.

Tamsulosin: Tamsulosin prescribed for symptomatic relief of benign prostratic hypertrophy may alter the tissue characteristics of the iris, rendering it floppy to manipulation. This may heighten the difficulty of performing cataract surgery, necessitate the use of iris-hooks, and prolong surgical duration. If not discontinued, a dense regional anesthetic block and/or deeper sedation may be needed.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac, pulmonary, renal, neurologic, and psychiatric medications should be continued.

Antiplatelet medication continuation is controversial. See discussion above.

j. How to modify care for patients with known allergies

N/A

k. Latex allergy - If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

Equipment and lens implants used in cataract surgery generally do not contain latex.

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

Routine administration of intravenous prophylactic antibiotics is not indicated for cataract surgery.

m. Does the patient have a history of allergy to anesthesia?

Occasionally, patients will present with a purported history of procaine allergy. Amino-amide local anesthetics such as lidocaine, bupivacaine, and ropivacaine are the most commonly used agents for ophthalmic anesthesia, rendering use of amino-ester agents unnecessary.

5. What laboratory tests should be obtained and has everything been reviewed?

Routine preoperative laboratory testing has not been shown to improve outcome. The need for studies should be determined based upon the results of the preoperative history and physical examination. Patients who present for cataract surgery are often elderly and have a plethora of concomitant medical issues. In general, they may have medical issues that have become exacerbated or are poorly controlled such that they require investigation. Selective testing based upon the history and physical is indicated.

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

Axial Length: Measurement of the anteroposterior length of the globe is requisite in order for the ophthalmologist to calculate the appropriate lens implant for cataract surgery. An eye with an elongated axis has greater size and volume than a globe of normal length and may be more readily injured by a block needle. A length of 25 mm or more is considered atypical. If one is planning on performing the eye block, the axial length should be noted.

Hemoglobin levels: Not routine

Electrolytes: Not routine.

Coagulation panel: See discussion above.

Imaging: Not routine.

Other tests: Only as indicated by history and physical.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Anesthesia options for patients undergoing cataract surgery include general anesthesia, intraconal (retrobulbar) block, extraconal (peribulbar) injection, sub-Tenon's block, and topical analgesia. The majority of patients having routine cataract surgery receive monitored anesthesia care and either topical analgesia or some form of regional block.

a. Regional anesthesia

In addition to rendering the globe and surrounding eye insensate, ophthalmic regional anesthesia offers the benefit of an akinetic globe and a motionless surgical field for the surgeon to work in. Blocks are categorized as needle-based or cannula-based. Topical anesthesia is also discussed.

Needle-based blocks

  1. The anatomical basis of needle-based blocks rests upon the key concept of the intraorbital muscle cone septum. This complex is comprised of the four ocular rectus muscles, having origin at the Annulus of Zinn at the apex of the orbit and extending forward to their respective insertions into the globe. Taken together with their surrounding connective tissue, these muscles create a cone-like structure situated just posterior to the globe.

  2. A retrobulbar block consists of placing a needle tip behind ("retro") the globe ("bulbar"). A more descriptive and anatomically proper term, intraconal block, relates to the position of the needle tip inside of the muscle cone. Injection of a low volume of local anesthetic (1-3 mL) via a steeply angled and somewhat deeply placed needle will produce swift onset of akinesia and analgesia. For patients that are prone to blepharospasm (tight eyelid squeezing), a separate injection seeking to block a branch of the facial nerve leading to the orbicularis oculi may be warranted.

  3. Numerous studies have proven that the intraorbital muscle septum is porous in nature. Local anesthetics deposited outside of the complex diffuse inward. Thus, anesthesia of the globe and orbit can be achieved by instilling local anesthetics exterior to the muscle cone. This extraconal block has also been known as a peribulbar ("around" the "globe") anesthetic.

  4. An extraconal block is achieved by directing a minimally angled, short needle to a shallow depth such that the tip becomes situated outside of the muscle cone. Larger volumes of local anesthetic are required to obtain sufficient ingress into the cone. Onset of anesthesia and akinesia are more gradual. A separate facial nerve injection is usually not required as some portion of the local anesthetic diffuses forward and creates lid akinesia.

  5. Complications associated with needle-based blocks include superficial or retrobulbar hemorrhage, precipitation of the oculocardiac reflex (bradydysrhythmia), postoperative diplopia, puncture or penetration of the globe, intraocular injection of local anesthetics and subsequent poor visual prognosis, optic nerve trauma, central retinal artery occlusion, and blindness. Due to proximity to the central nervous system, intravascular injection of local anesthetics can produce immediate onset of seizure activity, abrupt loss of consciousness, apnea, and cardiac instability. The optic nerve is covered by dura. Dispersal and spread of local anesthetics along the optic nerve sheath can induce brainstem anesthesia, characterized by delayed-onset loss of consciousness, respiratory depression, and cardiovascular instability.

  6. A differential diagnosis of altered physiologic status after needle-based eye block includes oversedation, intravascular injection of local anesthetics, and brainstem anesthesia. All three may present with varying levels of consciousness, apnea, and cardiac issues. The diagnosis of oversedation may be confirmed upon response to administration of narcotic and/or benzodiazepine reversal agents. The response to intra-arterial injection is rapid and seizure activity occurs virtually instantaneously. Brainstem anesthesia tends to have a longer latency of onset. Mydriasis (pupil dilation) and akinesia of the contralateral eye indicates local anesthetic travel across the optic chiasm and is diagnostic.

  7. An intraconal block is safer, in theory, as the needle is not directed deeply and toward the apex of the orbit where the optic nerve, muscle origins, and vasculature ingress are located. This distance from key structures decreases the likelihood of causing optic nerve injury, dural sheath penetration, orbital epidural injection, and brainstem anesthesia.

  8. Cannula-based blocks

    1. The anatomical basis of cannula-based blocks rests upon the key structure, Tenon's capsule. The capsule overlays and surrounds the sclera, the globe's tough outer layer, providing a smooth frictionless environment for globe movement. Tenon's capsule originates near the limbal margin, where it is fused to the conjunctiva. It extends posteriorly towards the optic nerve, encompassing the entire globe as well as portions of the extraocular muscles.

    2. A sub-Tenon's block consists of placing a cannula (or needle) into the episcleral space underneath Tenon's capsule. Local anesthetics instilled into this potential space will flow posteriorly to the optic nerve as well as to the ciliary nerves that penetrate the capsule en route to the globe.

    3. Common minor complications include subconjunctival hemorrhage, conjunctival chemosis, and incomplete akinesia or anesthesia. Case reports of rare serious complications include postoperative diplopia, puncture or penetration of the globe by the cannula or scissors, intraocular injection of local anesthetics, optic nerve trauma, central retinal artery occlusion, brainstem anesthesia, and even death.

Topical anesthesia

  1. Topical anesthesia is achieved by placing anesthetic drops and/or gels on the surface of the globe. It does not provide any degree of akinesia and patients maintain the ability to see during the procedure.

  2. Advantages offered by topical anesthesia include its quick, simple, noninvasive characteristics and the fact that patients have functional vision immediately after surgery.

  3. Disadvantages include the lack of a motionless operative field and the minimal degree of anesthesia obtainable. Patients with dense or complex cataracts and/or photophobia, blepharospasm (lid squeezing), or high-anxiety may warrant a different anesthetic technique. Since the patient must remain relatively still during cataract surgery, one may be tempted to deeply sedate an uncomfortable topical anesthesia patient, increasing the risk of intraoperative movement and poor visual outcome.

  4. Anesthetic gels such as lidocaine may yield superior surface analgesia compared with anesthetic drops. Gels, however, may act as a barrier to antiseptic agents, increasing the potential for postoperative endophthalmitis. Povidone-iodine should be placed prior to gel. However, it is rather caustic, thus it should be preceded by instillation of anesthetic drops. Prolonged exposure to 10% povidone-iodine can cause corneal toxicity.

  5. The surgeon can do an intracameral injection of preservative-free lidocaine directly into the globe's anterior chamber to supplement topical anesthesia.

  6. Additional intravenous analgesics/sedative/hypnotics may be warranted during difficult or more-stimulating portions of the procedure, such as iris manipulation, suturing, or in the face of acute changes in intraocular pressure.

b. General anesthesia

In this patient population which is often elderly with multiple comorbidities, the goal of general anesthesia is to minimize increases in intraocular pressure, maintain cardiovascular stability, and avoid overly deep levels of anesthesia.

  1. Benefits of general anesthesia for cataract surgery: Not all patients have the capacity to remain quiescent during surgery. Infants, children, the developmentally delayed or challenged patients, patients with movement disorders, and those with certain psychiatric issues, for example, may benefit from the lack of motion conferred by a general anesthetic.

  2. Drawbacks include prolonged recovery, need for phase I recovery, and potential for abrupt spike of intraocular pressure upon emergence and extubation.

  3. Endotracheal tube intubation vs. supraglottic airway: Unless contraindicated, a supraglottic airway offers advantages over traditional endotracheal intubation. Intraocular pressure is increased by laryngoscopy and intubation upon induction of anesthesia, and by bucking, coughing, or straining on the tube during emergence from anesthesia. In contrast, with a supraglottic airway, there is minimal to no change in intraocular pressure upon placement, maintenance, or emergence from general anesthesia.

  4. Tape the nonoperative eye shut. During the "time out" reconfirm that the appropriate eye is exposed and not taped shut or draped!

  5. Airway access: By definition, with the surgeon, assistant, and microscope at the head of the OR table, intraoperative access to the patient's airway is limited. Confirm the position and security of the endotracheal tube/supraglottic airway and all monitoring lines prior to draping.

  6. Movement: Untoward movement during ophthalmic surgery can result in unfavorable ultimate visual outcome. General anesthesia is often an inappropriate alternative for the patient with a cough as there is an increased risk of laryngospasm, bronchospasm, and bucking/straining during emergence (and subsequent increases in intraocular pressure).

  7. Oculocardiac reflex: The oculocardiac reflex is an abrupt bradydysrhythmic or asystolic response to orbit or globe manipulation. It is more commonly encountered during light planes of general anesthesia, and with hypoxia or hypercarbia. Assure adequate depth of anesthesia as well as oxygenation and ventilation. Administration of anticholinergics preoperatively in order to prevent the oculocardiac reflex is a dubious strategy with variable effectiveness. Tachycardia secondary to anticholinergics may precipitate cardiac ischemia and thus have greater adverse consequences than a transiently induced bradydysrhythmia. Treatment of the oculocardiac reflex entails cessation of the causative stimulus and stopping further surgical manipulation until restoration of adequate rate and rhythm. This reflex tends to wane in response to repeated elicitations. If not, or in the face of asystole, consider administration of anticholinergic agents.

  8. Supplementation with a regional anesthetic: Intraoperative injection of local anesthetics diminishes the need for deeper planes of anesthesia and provides effective postoperative pain management.

  9. Consider endotracheal tube extubation under deep plane of general anesthesia in order to avoid emergence hypertension, coughing, or bucking that may precipitously raise intraocular pressure. Consider administering intravenous lidocaine (1mg/kg) or a small dose of remifentanil or propofol prior to extubation.

c. Monitored anesthesia care

Monitored anesthesia care includes administration of anxiolytics, sedative-hypnotics, analgesics, and other anesthetic agents; monitoring and support of vital functions; as well as diagnosis and management ofany medical issues during the surgical procedure. It also includes provision of psychological support and assurance of physical comfort.

Airway/ventilation: Patient airway status may become compromised due to regional anesthesia (Brainstem anesthesia, intravascular injection of local anesthetics) or sedation. See discussion above for differential diagnosis. Airway obstruction, hypoventilation, and hypercarbia may predispose towards abrupt patient movement.

Movement: Untoward movement during ophthalmic block or surgery can result in unfavorable ultimate visual outcome. About 20% of MAC closed claims cases in the ASA database occurred with patients having eye surgery. The most common causes were attributed to block issues and/or perioperative patient movement. The preoperative evaluation should seek to determine if there is an increased potential for gross movement during cataract surgery. Factors that increase likelihood include cough, post nasal drip, obstructive sleep apnea, pathologic anxiety, severe claustrophobia, fluctuating levels of consciousness during surgery, rebreathing of carbon dioxide under closely occluded surgical drapes, and more. Elective eye surgery should be postponed until the patient is capable of remaining relatively motionless during the procedure. Patients should be made aware of the risks.

Awareness: Ideally, patients should remain sufficiently alert during surgery in order to retain the ability to remain relatively still. Light planes of sedation will likely promote intraoperative awareness and recall. Consider preoperative consultation with the patient to create appropriate expectations of the surgical experience.

Oculocardiac reflex: The oculocardiac reflex is an abrupt bradydysrhythmic or asystolic response to orbit or globe manipulation. It can occur during administration of a regional anesthetic or during surgery. Administration of anticholinergics preoperatively in order to prevent the oculocardiac reflex is a dubious strategy with variable effectiveness. Tachycardia secondary to anticholinergics may precipitate cardiac ischemia and thus have greater adverse consequences than a transiently induced bradydysrhythmia. Treatment of the oculocardiac reflex entails cessation of the causative stimulus and stopping further surgical manipulation until restoration of adequate rate and rhythm. This reflex tends to wane in response to repeated elicitations. If not, or in the face of asystole, consider administration of anticholinergic agents.

Malignant hypertension: Phenylephrine drops are commonly administered prior to cataract surgery in order to dilate the pupils, creating greater surgical access. Drops can be absorbed systemically via drainage through the puncta onto the nasal mucosa, producing a moderate spike in arterial blood pressure. Malignant hypertension, dysrhythmias, myocardial ischemia, and myocardial infarction have occurred following 10% phenylephrine drop administration. Profound hypotension can be induced if long-acting antihypertensives are given in response to hypertension induced by short-acting phenylephrine drops. The use of 2.5% phenylephrine rather than 10% as well as limited application of total volume are recommended.

6. What is the author's preferred method of anesthesia technique and why?

What prophylactic antibiotics should be administered?

Prophylactic antibiotics are not indicated for routine cataract surgery.

What do I need to know about the surgical technique to optimize my anesthetic care?

Certain patient factors require additional surgical manipulation and may necessitate a fully anesthetized, akinetic globe. These include patients with dense or complex cataracts, glaucoma patients on pupil-constricting drops, as well as surgical use of iris hooks.

What can I do intraoperatively to assist the surgeon and optimize patient care?

One must appreciate the limited physiologic reserves and associated comorbidities that may be present in many geriatric patients scheduled for cataract surgery. A reduction in the standard dosing of hypnotics/sedatives due to decreased ED50 may be prudent. The key to successful cataract surgery is titration of fast-acting short-duration drugs that allow rapid return to baseline function. Short or ultra-short acting agents such as fentanyl and bolus-dose remifentanil are ideal. Large intermittent doses of propofol may produce fluctuating levels of consciousness and/or airway obstruction and result in gross patient movement.

What are the most common intraoperative complications and how can they be avoided/treated?

Movement and oculocardiac reflex as described above. Blepharospasm, a roving globe, and/or an uncomfortable patient can be problematic for all involved. Compensation via increasing the depth of sedation may result in airway obstruction, hypoventilation, and predisposition toward gross patient movement. Preoperative assessment with deliberate patient selection and judicious choice of type of anesthetic (topical vs. block vs. general) is requisite in order to provide optimal anesthesia care.

Positioning

Positioning may need to be modified for patients with significant scoliosis, lumbar or cervical spine pathology, or advanced arthritis. Pad bony areas and place pillows underneath the knees to relieve spine and lower back strain. Intravenous access should ideally be placed on the extremity that will be nearest the anesthesia provider. For MAC patients, surgical drapes should be tented such that they are not tightly adherent to the patient's face. Rebreathing may manifest as anxiety, hypertension, tachycardia, and diaphoresis. Consider placing a suction catheter by the patient's chin or blowing air underneath the drapes. For general anesthesia patients, orient the endotrachial tube or supraglottic airway away from the upper face. Oral Rae tubes or flexible LMAs are ideal. Tape the airway firmly in place to avoid accidental dislodgement during surgery or upon removal of drapes at the conclusion of the case. Assure sufficient space between the patient's head and the surgical ring wrist-rest.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

N/A

c. Postoperative management

What analgesic modalities can I implement?

Preoperative ophthalmic regional blockade confers postoperative analgesia. For straight-forward cataract procedures; oral analgesics are usually sufficient.

What level bed acuity is appropriate?

Surgery is most commonly performed on an ambulatory basis.

What are common postoperative complications, and ways to prevent and treat them?

Postoperative nausea, retching and/or vomiting may be due to a surgically-related increase in intraocular pressure. Consultation with the ophthalmologist may be warranted.

What's the Evidence?

Gayer, S, Zuleta, J. "Perioperative management of the elderly undergoing eye surgery". Clin Geriatr Med. vol. 24. 2008. pp. 687-700.

Charles, S, Rosenfeld, PJ, Gayer, S. "Medical consequences of stopping anticoagulants prior to intraocular surgery or intravitreal injections". Retina. vol. 27. 2007. pp. 813-5.

Schein, OD, Katz, J, Bass, EB. "The value of routine preoperative medical testing before cataract surgery". N Engl J Med. vol. 342. 2000. pp. 168.

Gayer, S, Kumar, CM. "Ophthalmic regional anesthesia techniques". Minerva Anesthesiol. vol. 74. 2008. pp. 23-33.

Gayer, S. "Ophthalmic anesthesia: More than meets the eye". American Society of Anesthesiologists Refresher Courses in Anesthesiology. vol. 34. 2006. pp. 55-63.

Bhananker, SM, Posner, KL, Cheney, FW, Caplan, RA, Lee, LA, Domino, KB. "Injury and liability associated with monitored anesthesia care". Anesthesiology. vol. 104. 2006. pp. 228-34.

Gayer, S. "Key components of risk associated with ophthalmic anesthesia". Anesthesiology. vol. 105. 2006. pp. 859.

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