Historically, cataract surgery was performed without anesthesia. Karl Koller used topical cocaine anesthesia of the limbus in the late 1800s. Retrobulbar anesthesia was first described in 1884 by Herman Knapp, who injected 4% cocaine for ocular anesthesia prior to enucleation surgery. The modern technique of retrobulbar anesthesia, described in 1945 by Walter Atkinson, allowed the evolutionary advances of peribulbar and sub-Tenon anesthesia.
Retrobulbar anesthesia (
Figs 8-8 and 8-9Figs 8-8,
8-9), used with or without regional anesthesia of cranial nerve VII (facial nerve), provides excellent ocular akinesia and anesthesia. Complications of retrobulbar anesthesia are uncommon but include retrobulbar hemorrhage; globe penetration; optic nerve trauma; inadvertent intravenous injection associated with cardiac arrhythmias; and inadvertent intradural injection with associated seizures, respiratory arrest, and brain stem anesthesia (these complications are discussed more fully in BCSC Section 1, Update on General Medicine). A surgeon should know how to perform a lateral cantholysis to release a tense retrobulbar hemorrhage.
In peribulbar anesthesia, a shorter (1") 25- or 27-gauge needle is used to introduce anesthetic solution external to the muscle cone, underneath Tenon’s capsule, via single or multiple injection sites. Theoretically, peribulbar anesthesia eliminates the risk of complications such as optic nerve injury and central nervous system spread of anesthesia from intradural injection (Fig 8-10; also see Fig 8-8B). However, the risk of globe penetration is not eliminated, and the peribulbar method is slightly less effective than the retrobulbar for providing akinesia and anesthesia. In addition, the onset of effect is slower.
Topical anesthesia has evolved as a natural extension of phacoemulsification with foldable IOLs. Advantages of topical anesthesia include no risk of ocular perforation, extraocular muscle injury, or central nervous system depression. Vision returns almost immediately, and patients are able to leave the operating room without being patched because no eyelid block is used.
Topical anesthesia is administered as topical proparacaine or tetracaine drops, cellulose pledgets, or lidocaine jelly. Topical anesthetic agents are used with or without intravenous sedation. Topical anesthesia may be supplemented with the intracameral use of preservative-free lidocaine. Only nonpreserved lidocaine, generally 1%–2%, should be used for anterior chamber instillation, as some preservative agents can be toxic to intraocular structures. Transient amaurosis due to a direct retinal effect has been reported following the use of intracameral anesthetics, more commonly in patients with open posterior capsules or previous vitrectomy. Topical anesthesia should be reserved for the cooperative cataract patient who, with a dilated pupil, can tolerate the microscope light.
The type of anesthesia appropriate for the individual patient should be considered carefully. A general discussion of the advantages and risks of the different types of anesthesia should accompany the informed consent process. A discussion of what the patient will experience in the operating room will increase the likelihood of achieving a more relaxed patient on the day of surgery.
Subconjunctival lidocaine (Xylocaine) can be used to augment topical anesthesia in patients who experience sensation after administration of topical tetracaine or intracameral lidocaine. A 30-gauge needle is used to inject the lidocaine posterior to the phaco incision.
Sub-Tenon (Fig 8-11) infusion of lidocaine (Xylocaine) can be used to provide anesthesia and moderate akinesia during surgery. Lidocaine is administered through a cannula or catheter placed into a small posterior incision, under conjunctiva and Tenon’s capsule.
A facial nerve block (Fig 8-12), common in the era of large-incision ICCE/ECCE, is not generally needed with small-incision surgery. However, patients with essential or reactive blepharospasm may require a facial block to avoid complications during surgery.
General anesthesia, with clearance from the patient’s primary care physician or an anesthesiologist, is appropriate to consider for pediatric patients and for patients who have any condition that would prevent their cooperation during surgery, including head tremor, deafness, neck or back problems, restless legs syndrome, or claustrophobia.
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