Anesthesia for Cataract Surgery
Consideration of the options for anesthesia is an important part of preoperative planning. A general review of the advantages and risks of the different types of anesthesia is part of the informed consent process. A discussion of what the patient will experience in the operating room increases the likelihood of comfort and cooperation on the day of surgery. (See also BCSC Section 1, Update on General Medicine, for a discussion of perioperative management in ocular surgery.)
Retrobulbar anesthesia for cataract surgery provides excellent ocular akinesia and anesthesia and reduces sensitivity to the microscope light. The basic technique of retrobulbar injection (Fig 7-3), first described in 1945 by Walter Atkinson, involves administration of lidocaine into the muscle cone via a 25-gauge, 1.5-inch (38-mm) blunt retrobulbar needle. Many surgeons now use a 27-gauge, 1.25-inch sharp needle and supplement the lidocaine with vitrase and bupivacaine, and sometimes bicarbonate. These modifications can enhance the patient’s comfort, speed of onset, and duration of the retrobulbar block. Complications resulting from retrobulbar anesthesia are uncommon but include retrobulbar hemorrhage; globe penetration; optic nerve trauma; extraocular muscle toxicity; inadvertent intravenous injection associated with cardiac arrhythmia; and inadvertent intradural injection with associated seizures, respiratory arrest, and brainstem anesthesia. Any preexisting diplopia or ocular misalignment should be documented.
Figure 7-3 Retrobulbar injection.
(Courtesy of Michael N. Wiggins, MD.)
Peribulbar anesthesia theoretically eliminates the risk of complications such as optic nerve injury and intradural injection. However, it is slightly less effective than the retrobulbar method for providing akinesia and anesthesia and is more likely to give conjunctival chemosis. In this technique, a shorter (1-inch) 25-gauge or 27-gauge needle is used to introduce anesthetic solution external to the muscle cone, underneath the Tenon capsule.
Sub-Tenon infusion of lidocaine has become a popular method of anesthesia during surgery. The risk of muscle injury or toxicity associated with this method is lower. A small, posterior incision is made through anesthetized conjunctiva and the Tenon capsule, and a small cannula is used to administer the anesthetic (Video 7-1; Fig 7-4).
Sub-Tenon injection. Courtesy of Charles Cole, MD.
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The use of topical and intracameral anesthesia has increased. With topical anesthesia, the risk of ocular perforation, extraocular muscle injury, and central nervous system depression is eliminated, and visual recovery is accelerated. Topical anesthesia is administered via proparacaine or tetracaine drops, cellulose pledgets soaked in anesthetic, or lidocaine jelly. Intracameral preservative-free lidocaine (which often includes a mydriatic agent) can supplement or even replace topical anesthesia. Lidocaine/phenylephrine (Shugarcaine) has the added advantage of increasing pupil dilation and reducing the effects of intraoperative floppy iris syndrome (IFIS). Only nonpreserved 1% or 2% lidocaine should be used for anterior chamber instillation, because of the toxic effect of some preservative agents on intraocular structures. Disadvantages of topical anesthesia include blepharospasm, lack of akinesia, and potential patient discomfort, which can interfere with the surgeon’s ability to perform delicate maneuvers. Topical and intracameral anesthesia is typically reserved for short cataract surgeries, generally under 30 minutes in length, with cooperative patients who are well dilated and can tolerate the microscope light. Topical and intracameral anesthesia can be supplemented with oral or intravenous sedation to help reduce patient anxiety.
Figure 7-4 Sub-Tenon injection.
A facial nerve block, common in the era of large-incision intracapsular cataract extraction (ICCE) and extracapsular cataract extraction (ECCE), is not generally necessary with small-incision surgery. However, patients with essential or reactive blepharospasm may benefit from a facial nerve block to control squeezing during surgery. Types of facial nerve blocks include the O’Brien block, directed proximally and peripherally at the nerve trunk; the van Lint block, directed proximally and peripherally at the terminal branches; and the Atkinson block, directed between these two regions (Fig 7-5).
General anesthesia can be considered for pediatric patients and for adult patients who have any condition that would prevent their cooperation and ability to lie flat during surgery, including dementia, head tremor, deafness, language barrier, musculoskeletal disorder, restless legs syndrome, claustrophobia, or psychiatric disorder (including anxiety). Patient preference can also be considered as an indication. General anesthesia may require clearance from the patient’s primary care physician or an anesthesiologist.
Figure 7-5 Akinesia of orbicularis oculi. A, Van Lint akinesia. B, O’Brien akinesia. C, Atkinson akinesia. D, Nadbath-Ellis akinesia.
(Reproduced with permission from Jaffe NS, Jaffe MS, Jaffe GF. Cataract Surgery and Its Complications. 5th ed. Mosby; 1990.)
Schimek F, Fahle M. Techniques of facial nerve block. Br J Ophthalmol. 1995;79(2):166–173.
Zhao LQ, Zhu H, Zhao PQ, Wu QR, Hu YQ. Topical anesthesia versus regional anesthesia for cataract surgery: a meta-analysis of randomized controlled trials. Ophthalmology. 2012;119(4): 659–667.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.