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February 16, 2001

Topical anesthesia versus retrobulbar block for cataract surgery: the patients’ perspective

Boezaart A, Berry R, Nell M. J Clin Anesth. 2000; 12:58-6.

Commentary by Kathryn McGoldrick, M.D.

Return to the Current Literature Review

see abstract below

The anesthetic options for cataract surgery include general anesthesia, retrobulbar blockade, peribulbar blockade, parabulbar methods of sub-Tenon’s anesthesia, and topical anesthesia. In the United States today general anesthesia is administered only rarely in conjunction with cataract surgery. Typically, either regional block or topical analgesia is used. Nonetheless, it is imperative to appreciate that the complications of ophthalmic anesthesia can be potentially vision-threatening or life-threatening.

Retrobulbar blockade entails injection of local anesthesia behind the eye into the muscle cone. Often a facial nerve block is performed in conjunction with retrobulbar block to prevent squeezing of the eyelid that could result in extrusion of intraocular contents if the ocular incision is large. It is important not to be lulled into a false sense of security with retrobulbar anesthesia, however, because this technique does not necessarily involve less physiologic trespass than does general anesthesia. The most common serious complication of retrobulbar block is retrobulbar hemorrhage (incidence: 1 to 3%). Other major complications include, but are not limited to, direct intravascular injection that can produce virtually instantaneous seizures if located intra-arterially, stimulation of the oculocardiac reflex; puncture of the eye ball producing retinal detachment and vitreous hemorrhage; unintentional intraocular injection; central retinal artery occlusion; and penetration of the optic nerve. Optic atrophy may occur as a result of direct injury to the nerve, injection into the nerve sheath with ensuing compressive ischemia, and penetration of the optic nerve. An initially insidious but potentially fatal complication may also develop when accidental access to cerebrospinal fluid during performance of a retrobulbar block occurs owing to perforation of the meningeal sheath that surrounds the optic nerve. This can result in the gradual onset of unconsciousness, cessation of breathing, and cardiovascular collapse. Clearly, there is a continuum of sequelae, depending on the amount of drug that gains entrance to the central nervous system and the specific area of the brain to which the drug spreads. In a series of 6000 retrobulbar blocks, Nicoll reported 16 cases of apparent central spread of local anesthesia; respiratory arrest developed in 8 of the 16 patients [1].

Because of the potentially serious complications of retrobulbar block, alternative methods of local anesthesia have been developed. Since the late 1980s, peribulbar block has become popular because, when this approach is properly performed, the muscle cone is not entered. Therefore, theoretically, injury to the optic nerve should be prevented and the likelihood of central spread of local anesthetic should be greatly minimized. Ocular perforation, however, has been reported, as have peribulbar hemorrhage and ecchymoses. Additionally, some surgeons object to increased forward pressure on the eyeball consequent to the larger volume of local anesthetic deposited in the orbit compared with retrobulbar block. Moreover, it should be noted that both retrobulbar and peribulbar block can be painful for the patient when administered, and sedation is typically given. Administration of this short-acting sedation can, in and of itself, occasionally produce allergic reactions, cardiac depression, respiratory depression, loss of airway patency, and inadequate oxygenation of the patient.

A parabulbar method of sub-Tenon’s infusion of anesthetic via a flexible, curved cannula also has been developed. Because it does not involve the use of a sharp needle, this approach eliminates the risk of globe penetration, retrobulbar hemorrhage, and optic nerve trauma.

During the past seven or eight years ophthalmologists have increasingly been returning to a technique that was popularized during the early 1900s -- the use of topical anesthetic agents, particularly when the surgical incision is being made through clear cornea. Many advances in cataract surgery that have enabled faster operations with greater control and less trauma have allowed ophthalmologists to re-examine the use of topical anesthesia for this procedure. Phacoemulsification, with its small incision, is the procedure of choice for using topical anesthesia; however, planned extracapsular procedures can also be performed under topical anesthesia, thereby circumventing potential complications of retrobulbar or peribulbar block that can result in blindness or death. Potential disadvantages of topical anesthesia are typically less serious and include eye movement during surgery, patient anxiety, and, rarely, allergic reactions. Patient selection is important and should be restricted to individuals who are alert, able to follow instructions, and can control their eye movements. Patients who are demented, photophobic, or cannot communicate are inappropriate candidates, as are those individuals with an inflamed eye. Similarly, patients with small pupils who may require significant iris manipulation or those who need large scleral incisions generally are excluded as candidates for topical anesthesia.

Clearly, the risk of major complications associated with topical analgesia are significantly less than with other types of ocular anesthesia. This study by Boezaart and colleagues, however, serves to remind us that in medicine (as in life) nothing is ever perfect and sometimes it is necessary to sacrifice a bit of comfort for a considerable amount of safety.

Reference:

  1. Nicoll JMV, Acharya PA, Ahlen K, et al: Central nervous system complications after 6000 retrobulbar blocks. Anesth Analg 66;1298, 1987. Link to abstract

ABSTRACT


Topical anesthesia versus retrobulbar block for cataract surgery: the patients’ perspective

AUTHORS:
Boezaart A, Berry R, Nell M

SOURCE:
J Clin Anesth. 2000; 12:58-6

ABSTRACT:
STUDY OBJECTIVES: To compare patients' perception of topical anesthesia (TA) with combined peribulbar and retrobulbar block (PRBB) for cataract surgery. DESIGN: Prospective, randomized, controlled, cross-over observational study. SETTING: Private clinic. PATIENTS: 98 ASA physical status I and II patients presenting for bilateral cataract surgery 1 week apart. INTERVENTIONS:Patients were prospectively randomized to receive either TA for surgery to one eye, followed by PRBB for surgery to the other eye 1 week later, or to receive PRBB first, followed by TA for the second operation the following week. Surgery, PRBB, and TA were standard for all cases. Interviews were conducted the day following surgery by an unbiased observer unaware of the technique used. Surgical pain was estimated on a visual analog scale of 0 to 10, and the surgeon judged the difficulty of surgery based on patient compliance and cooperation on a scale of 0 to 5. Means and variance of results were compared with analysis of variance. MEASUREMENTS AND MAIN RESULTS: Mean age was 71.45 +/- 9.76 years (mean +/- SD). Seventy patients (71.43%) preferred PRBB while 10 patients (10.20%) preferred TA (p = 0.0001). Eighteen patients (18.37%) reported no difference between the two techniques. Ninety-six patients (97.96%) were not aware of the PRBB being injected. Duration of surgery was similar for TA (11.92 +/- 3.43 min) and PRBB (10.78 +/- 3.00 min; p = 0.06). Surgery was more difficult during TA (p = 0.0004). Pain was worse during TA (p = 0.0001). Surgical and anaesthetic complications were unremarkable for both techniques. CONCLUSIONS: Patients who experienced both TA and PRBB preferred PRBB.

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