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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:
- 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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