Full text of DOI:10.1097/00061198-200208000-00006

Journal of Glaucoma 11:306–314
© 2002 Lippincott Williams & Wilkins, Inc.
A Comparison of Topical and Retrobulbar Anesthesia
for Trabeculectomy
*Norman A. Zabriskie, MD, *Iqbal Ike K. Ahmed, MD, *Alan S. Crandall, MD,
*Brad Daines, MD, †Thomas A. Burns, MD, *Bhupendra C. K. Patel, MD
*John A. Moran Eye Center and †Department of Anesthesia, University of Utah Health Sciences Center, Salt Lake City, Utah
Purpose: To compare the safety and efficacy of topical versus retrobulbar anes-
thesia for primary trabeculectomy
Methods: A prospective study of 36 consecutive patients undergoing trabeculec-
tomy who were randomized to receive topical (n ס 18) or retrobulbar (n ס 18)
anesthesia. Operating conditions, patient comfort, and surgical outcome were evalu-
ated.
Settings: Tertiary-care university hospital ambulatory surgical center.
Results: There were no differences in operating conditions (P ס 0.14), pain during
(P ס 0.54) or after (P ס 0.76) surgery, or supplemental anesthesia required (P ס
0.34) between the two groups. Very few patients in either group were bothered by
touch sensation, tissue manipulation, or the microscope light. Chemosis, subconjunc-
tival hemorrhage and eyelid hemorrhage were seen exclusively in the retrobulbar
group (P <0.03), and were all attributable to the injection. Inadvertent eye movement
was present more frequently in the topical group (P ס 0.01), although this did not pose
a problem to the surgeon. No surgical complications were encountered in either group.
Conclusion: Topical anesthesia is a safe and effective alternative to retrobulbar
anesthesia for primary trabeculectomy.
Key Words: Retrobulbar anesthesia—Trabeculectomy—Topical anesthesia.
Several methods of local anesthesia for anterior seg-
ment surgery are currently in use, including retrobulbar,1
peribulbar,2,3 subconjunctival,4 sub-Tenon,5 and the ap-
plication of topical anesthetic drops.6 Topical anesthesia
is an increasingly popular technique for cataract surgery,
and is equally effective as other methods of anesthesia.7,8
However, little has been reported concerning the appli-
cation of topical anesthesia in glaucoma surgery.9
The use of topical anesthesia during glaucoma sur-
gery, as for cataract surgery, is an attractive alternative to
injection anesthesia since very serious complications can
occur with the latter method. These complications in-
clude globe perforation, retrobulbar hemorrhage, central
retinal artery occlusion, orbital infection, chronic my-
driasis, optic nerve injury, intravascular or intrathecal
injection, respiratory depression, apnea, cranial nerve
palsy, and death.7,10–16 More common complications
with retrobulbar anesthesia include eyelid and subcon-
junctival hemorrhage, chemosis, postoperative diplopia,
ptosis, nausea, and systemic hypertension.7,17,18 Al-
though peribulbar anesthesia reduces the risk of optic
nerve injury, it has the potential for hemorrhage and
globe perforation, is time-consuming, and requires a
greater volume of anesthetic than retrobulbar tech-
niques.19,20
Received September 26, 2001; accepted after revision March 13,
2002.
Supported in part by a grant from Research to Prevent Blindness,
Inc., New York, NY, to the Department of Ophthalmology and Visual
Sciences, University of Utah, Salt Lake City, UT.
The authors have no propriety interest in any of the materials used in
this study.
Address correspondence and reprint requests to Norman A.
Zabriskie, MD, John A. Moran Eye Center, University of Utah Health
Sciences Center, 50 North Medical Drive, Salt Lake City, UT 84132.
To determine whether topical medication alone could
306
DOI: 10.1097/01.IJG.0000021866.39905.3B

TOPICAL VERSUS RETROBULBAR ANESTHESIA FOR TRABECULECTOMY
307
provide adequate anesthesia for glaucoma surgery, we
designed a prospective randomized study comparing
topical versus retrobulbar anesthesia for trabeculectomy.
Specifically, patient comfort and the ability to safely per-
form the operation were studied. A protocol similar to
that of two previous studies7,21 was used.
(approximate dose, 0.5–1 mg/kg) after 2 minutes of pre-
oxygenation with 100% oxygen by face mask. When the
patient was unconscious, a retrobulbar block was per-
formed with a 23-gauge retrobulbar needle using a solu-
tion of 2 mL lidocaine hydrochloride 2% (Abbott Labo-
ratories), 2 mL bupivacaine hydrochloride 0.75%, and
150 U hyaluronidase (Wydase, Wyeth Laboratories,
Philadelphia, PA). No ocular compression was per-
formed, and facial or eyelid blocks were not used.
Surgery was performed after routine preparation and
draping. If breakthrough pain occurred during surgery,
supplemental topical bupivacaine 0.75% (two drops) was
administered. If this was not effective, fentanyl (0.5
␮g/kg) was given intravenously, and repeated after 3
minutes if necessary. Supplemental block anesthesia was
then administered if this was not effective.
One surgeon (A.S.C.) performed all surgical proce-
dures in this study. An open-wire speculum was placed,
and no traction sutures were used. Under low-
microscope lighting, a fornix-based conjunctival flap
was fashioned in the superior quadrant initiated by a
5-mm limbal peritomy. Light cautery was used for he-
mostasis. A 4 × 3-mm trapezoidal scleral flap was then
made with a diamond blade, dissecting into clear cornea
with a diamond crescent blade at approximately 70%
depth. A Merocel sponge soaked with mitomycin C (Mu-
tamycin, Bristol Laboratories, Princeton, NJ) 0.2 mg/mL
was then placed under the flap and left for 2 minutes,
followed by copious irrigation with balanced-salt solu-
tion. A diamond blade was used to make a stab inci-
sion. The anterior chamber was then entered under the
scleral flap using a diamond keratome. A Crozafon-
DeLaange Descemet punch was used to make the scle-
rostomy, and a peripheral iridectomy was cut. The scleral
flap was then closed with a 10–0 nylon suture at each
corner, and adjustable knots were used to allow titration
of the flow under the flap. Once the flow was considered
appropriate, the knots were tied off and cut. The con-
junctiva was then closed using a 10–0 Vicryl suture
(Ethicon, D-7329, VAS100–4 needle) in a running hori-
zontal mattress fashion. The conjunctival wound was
checked for leakage and, if leakage was found, the area
was oversewn.
PATIENTS AND METHODS
The University of Utah Institutional Review Board
approved the study, which enrolled consecutive patients
undergoing elective primary trabeculectomy without pre-
vious surgery involving the conjunctiva. Patients in-
cluded men and women between 45 and 85 years who
met the American Society of Anesthesiology (ASA)
physical status class 1, 2, or 3 criteria. Patients with
communication difficulties, monocular patients, and pa-
tients taking anticoagulation medications were excluded.
Informed consent was obtained and all patients were as-
signed either to the topical anesthetic group (topical
group) or to the retrobulbar anesthetic group (retro-
bulbar group) by permuted block randomization.
Operative Procedures
Baseline vital signs were taken in all patients preop-
eratively, and an intravenous line with Ringer’s lactate
solution was placed. The topical group received two
drops of nonpreserved bupivacaine hydrochloride 0.75%
(pH 5.4; Abbott Laboratories, North Chicago, IL) every
5 minutes three times in the preoperative holding area
beginning 20 minutes before the procedure. The method
of bupivacaine delivery was the same as the standard
protocol used in our surgery center. Six separate sterile
3-mL syringes were used to draw 1.5 mL solution from
a 10-mL single-dose vial of bupivacaine. The individual
syringes required for the entire day were drawn up in the
morning. A separate syringe was used to deliver the bu-
pivacaine to each patient. The retrobulbar group received
no anesthesia in the preoperative holding area.
In the operating room, all patients received continuous
nasal prong oxygen (4 L/min) and baseline vital signs
were obtained.
At the conclusion of the case, a collagen shield soaked
in cefazolin (American Pharmaceutical Partners, Inc.,
Los Angeles, CA) and dexamethasone (American Regent
Laboratories, Inc., Shirley, NY) was placed as well as a
drop of atropine 1%. All patients were patched. After the
surgery, patients were taken to the postoperative area
where vital signs were obtained. The patients were kept
in the recovery area for a minimum of 30 minutes.
Prior to draping, the topical group was given 0.015-
mg/kg midazolam hydrochloride (Versed, Roche Phar-
maceuticals, Nutley, NJ) and 1-␮g/kg fentanyl citrate
(Elkins-Sinn, Inc., Cherry Hill, NJ) intravenously, and an
additional two drops of bupivacaine 0.75%.
Patients randomized to the retrobulbar group were
given methohexital sodium 1% (Brevital, Jones Pharma,
Inc., St. Louis, MO) titrated to produce unconsciousness
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N. A. ZABRISKIE ET AL.
TABLE 1. Operative conditions and complications
Data Collection
Topical
Retrobulbar
(n ס 18)
(n ס 18)
P
Immediately after surgery, a constant observer col-
lected patient assessment responses in the recovery area
without the presence of the surgeon. Questions were pre-
sented to the patients from a standard written form. Each
patient was shown a 10-point visual analogue pain scale
with both written and numeric indices (Fig. 1). Each
patient was asked to grade the level of pain during de-
livery of anesthesia, during surgery, and postoperatively
on separate scales. If the patient was unable to see the
scale or read the accompanying text, the scale was de-
scribed and a verbal response was obtained. Patients
were also asked to assess the degree to which they were
bothered by the sensation of touch and tissue manipula-
tion and by the operating microscope light. The degree to
which each of these bothered the patient was graded as
none, a little, or a lot, and given a score of 0, 1, or 2,
respectively, for statistical purposes.
Supplemental periocular
anesthesia (injection)
Supplemental topical
anesthesia
Supplemental IV anesthesia
(fentanyl)
Squeezing of eyelids present
Inadvertent eye movement
Retrobulbar hemorrhage
Globe perforation
Chemosis
Eyelid hematoma
Subconjunctival hemorrhage
Cooperation
0
0
1.00
0.34
4 (22%)
1 (6%)
2 (11%)
6 (33%)
10 (56%)
0
0
0
0
0
1 (6%)
2 (11%)
2 (11%)
0
1.0
0.23
0.01*
1.00
1.00
<0.001*
<0.001*
0.02*
0
12 (67%)
10 (56%)
6 (33%)
Excellent
Good
Poor
16 (89%)
2 (11%)
0
14 (78%)
4 (22%)
0
0.38
* Difference was statistically significant.
tive period, and patient cooperation were performed us-
ing the Wilcoxon (Mann-Whitney) rank sum test. Di-
chotomous comparisons were performed with Fisher ex-
act tests. The null hypothesis was rejected for
probabilities of type I error less than 0.05 (P <0.05).
The surgeon also completed an assessment question-
naire immediately after each surgery. Lid squeezing, in-
advertent eye movement, and surgical complications
were noted if present. Patient cooperation was graded as
excellent, good, or poor. The surgeon also rated the over-
all surgical conditions on an analogue scale with 10 rep-
resenting excellent, 7.5 good, 5 fair, 2.5 poor, and 0
extremely poor. Complications and the need for supple-
mental anesthesia were recorded.
Statistical analyses were performed using SPSS 9.0 for
Windows (SPSS Inc., Chicago, IL).
Comparisons between the topical and retrobulbar
groups for the operative conditions, pain during delivery
of anesthesia, pain during surgery, pain in the postopera-
RESULTS
Eighteen patients were randomized to each group. Op-
erative conditions and complications are given in Table
1. There were no intraoperative complications in either
group.
Overall patient cooperation as assessed by the surgeon
was similar for both the topical and retrobulbar groups,
and was rated excellent in 89% of the topical group and
78% in the retrobulbar group (P ס 0.38). No patient in
either group was rated as poorly cooperative.
There were no significant differences in the number of
patients in either group requiring supplemental IV or
topical anesthesia during surgery. No patient in the study
required supplemental periocular anesthesia.
Inadvertent eye movement was found more frequently
in the topical group (10 patients, 56%) than in the retro-
bulbar group (two patients, 11%) (P ס 0.01), but did not
interfere significantly with surgery in any of these pa-
tients. Lid squeezing was noted in six (33%) patients in
the topical group versus two (11%) patients in the retro-
bulbar group (P ס 0.23).
Chemosis (12 patients, 67%), eyelid hemorrhage (10
patients, 56%), and subconjunctival hemorrhage (six pa-
tients, 33%) attributable to the retrobulbar block were all
significantly higher in the retrobulbar group than in the
topical group where they were nonexistent (P <0.03).
FIG. 1. Descriptive and numerical-visual analogue pain scale.
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TOPICAL VERSUS RETROBULBAR ANESTHESIA FOR TRABECULECTOMY
309
Patient assessment of pain during the delivery of the
anesthetic was similar in each group (Fig. 2). Visual
analogue scores produced a mean score of 0.22 for the
topical group compared with 0.06 for the retrobulbar
group (P ס 0.15). Fourteen patients (78%) in the topical
group and 17 patients (94%) in the retrobulbar group
reported no pain during anesthesia delivery (P ס 0.3).
There was no difference in the patients’ perception of
pain during surgery (Fig. 3). The mean scores were 0.5
and 0.39 for the topical and retrobulbar group, respec-
tively (P ס 0.54). Eleven patients (61%) in the topical
group and 13 patients (72%) in the retrobulbar group
reported no pain during surgery (P ס 0.42).
Patients reported similar pain scores in the postopera-
tive period (Fig. 4). The mean score for postoperative
pain was 0.44 in the topical group and 0.39 in the retro-
bulbar group (P ס 0.76). Twelve (67%) patients in the
topical group and 13 (72%) patients in the retrobulbar
group reported no pain during the postoperative period
(P ס 0.4).
Figure 5 shows the operative conditions as assessed by
the surgeon. The conditions were overwhelmingly excel-
lent in each group, without any significant difference
between groups (P ס 0.14). Overall analogue scores
showed a mean of 9.72 in the topical group and 9.33 in
the retrobulbar group.
Figure 6 shows that patients reported similar scores for
bothersome tissue manipulation, touch sensation, and
microscope light. Mean scores for each group were 0.17
and 0.06 (P ס 0.60), 0.28 and 0.11 (P ס 0.46), and 0.17
and 0.06 (P ס 0.60) for the topical and retrobulbar
groups, respectively.
DISCUSSION
The use of topical anesthesia during cataract extrac-
tion is becoming increasingly popular. This trend is sup-
ported by studies showing no significant difference in
patient perception of pain between topical and retrobul-
bar anesthesia.7,8 Minor and major complications of ret-
robulbar anesthesia are also essentially eliminated by the
FIG. 2. Pain scores recorded for delivery of anesthesia.
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N. A. ZABRISKIE ET AL.
FIG. 3. Pain scores recorded during surgery. P = 0.54.
use of topical anesthesia. Additional benefits of topical
anesthesia include rapid visual recovery, no patching in
the immediate postoperative period, pain-free adminis-
tration without sedation, and a more cost-effective anes-
thetic regimen.22 Despite these well-documented advan-
tages of topical anesthesia for cataract surgery, little has
been published regarding the safety and efficacy of topi-
cal anesthesia in glaucoma surgery.
Topical anesthesia in glaucoma surgery has important
advantages over retrobulbar or peribulbar anesthesia. It
has been long thought that the injection of retrobulbar
anesthetic could cause a sudden increase in intraocular
pressure from the compression of the anesthetic itself on
the eye or from retrobulbar hemorrhage.13 Such an in-
crease in intraocular pressure could have damaging ef-
fects on an already compromised optic nerve. Also, topi-
cal anesthesia greatly reduces the risk of subconjunctival
hemorrhage, which can hinder surgery and is a potential
risk factor for filtration failure.
in 1992 reported on the effectiveness of sub-Tenon an-
esthesia. This was further substantiated by a prospective
study by Buys and Trope.24 Comparing subconjunctival
versus peribulbar anesthesia, Azuara-Blanco et al.25
found both techniques to be effective for trabeculectomy,
confirming findings of similar studies.26,27 However,
sub-Tenon or subconjunctival anesthesia is still a form of
“injection anesthesia,” with chemosis and undesirable
subconjunctival hemorrhage extending to more than one
quadrant occurring in up to 32% of patients.28 Globe
perforation has also been reported with this technique.29
Dinsmore9 found that while most patients (92% of 136
cases) undergoing only cataract extraction received ad-
equate pain control with topical anesthesia alone, two of
five combined procedures and three of five trabeculec-
tomies required additional anesthetic blocks because of
pain, most often during conjunctival manipulation and
suturing towards the end of surgery. The authors recently
demonstrated the effectiveness of topical anesthesia for
combined cataract and trabecutectomy surgery.29a
In a departure from traditional retrobulbar or peribul-
bar anesthesia for trabeculectomy, Ritch and Liebmann23
The present study demonstrates that topical anesthesia
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TOPICAL VERSUS RETROBULBAR ANESTHESIA FOR TRABECULECTOMY
311
FIG. 4. Pain scores recorded during the postoperative period. P = 0.76.
alone is an effective alternative to retrobulbar anesthesia
for primary trabeculectomy. Pain control with topical
anesthesia was equally efficacious to retrobulbar anes-
thesia, with both techniques resulting in very little pain
with delivery of anesthesia and during or after surgery.
The majority of patients in both the topical and retrobul-
bar groups reported no pain, and no patient in the topical
group required supplemental periocular block anesthesia.
Topical anesthesia provided excellent operative con-
ditions and patient cooperation in 89% of patients, which
was similar to the 78% of patients in the retrobulbar
group. Most patients in both groups were not bothered by
tissue manipulation, touch sensation, or the microscope
light.
Although there were significantly more patients in the
topical group with inadvertent eye movements (56% vs.
11%), this did not appreciably interfere with surgery. In
fact, the ability of patients to move their eye to a desired
position during the procedure was helpful in many cases.
Traction sutures were not used in this study, though they
certainly could be considered with this anesthetic tech-
nique if preferred by the operating surgeon. When using
topical anesthesia, a clear corneal bridle suture may be
used for either a fornix or limbus-based conjunctival flap
technique. Conversely, a superior rectus traction suture is
not advised when using topical anesthesia.
These results are not entirely surprising. Numerous
studies demonstrate that topical anesthesia for cataract
surgery is as efficacious as injection anesthesia without
its associated complications.7,8 Furthermore, as experi-
ence has increased with the use of topical anesthesia,
there have been additional reports of topical anesthesia in
complicated cataract extractions and in posterior vitrec-
tomies.30–32 However, considerations for glaucoma fil-
tering surgery with topical anesthesia are different from
those for small-incision, clear-cornea phacoemulsifica-
tion in many ways. Glaucoma surgery is generally of
longer duration, and cautery, scleral incisions, peripheral
iridectomy, conjunctival manipulation, and suturing all
may cause increased pain. Furthermore, some surgeons
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N. A. ZABRISKIE ET AL.
FIG. 5. Operative conditions rated by the surgeon on an analogue scale (10 = excellent, 7.5 = good, 5 = fair, 2.5 = poor, 0 = extremely
poor). P = 0.14.
may be uncomfortable with inadvertent eye movements
that may occur with topical anesthesia.
sided significance level (nQuery Advisor 4.0, Sangus,
MA). We think that this “minimum detectable effect”
would be able to detect all but the smallest of differences
in pain scores and is clinically appropriate. Also, this was
not a masked study as it would have been very difficult
to mask the patient and impossible to mask the surgeon.
However, the independent observer who collected pa-
tient responses postoperatively was masked to the anes-
thetic technique.
One potential concern about the study is the use of
sedation, which could affect patient recall when assess-
ing intraoperative pain levels after surgery. In addition,
different methods of sedation were used for each group.
Although it would be ideal if sedation was identical in
each group, this effect is difficult to achieve. If no or only
light sedation were used for both groups, this would re-
sult in an unacceptable pain level during anesthesia de-
livery in the retrobulbar group. Conversely, if the deep
level of sedation required for the retrobulbar group were
Compared to routine phacoemulsification, strategies to
improve patient comfort with topical anesthesia in glau-
coma surgery include 1) adequate preoperative counsel-
ing, 2) multiple administrations of topical anesthesia
starting at least 20 minutes preoperatively to allow suf-
ficient tissue penetration, 3) the addition of intravenous
sedation for anxiety and additional pain control, and 4)
supplemental topical anesthesia when needed—
particularly toward the end of surgery when handling and
suturing the conjunctival flap.
Limitations of this study include a small sample size
(18 patients each in the topical and retrobulbar groups)
for which nonparametric statistics were performed to de-
termine significance levels. Power analysis showed that
this study sample had a power of 80% to detect a differ-
ence of 0.68 on a 0–10 analogue pain scale using a Wil-
coxon (Mann-Whitney) rank sum test with a 0.05 two-
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TOPICAL VERSUS RETROBULBAR ANESTHESIA FOR TRABECULECTOMY
313
FIG. 6. Patient perception of tissue manipulation, touch sensation, and microscope light during surgery. Patients were asked to assess
whether each of these bothered them a lot, a little, or not at all.
delivered to the topical group, the patient cooperation
required for successful topical surgery would be com-
promised. For these reasons, when comparing retrobul-
bar and topical anesthesia, one must consider intravenous
sedation as part of that group’s anesthesia technique, not
as an additional confounding variable.
As sedation was required for the retrobulbar group, it
was decided that both groups would get some form of
sedation. Methohexital was used when administering the
retrobulbar anesthesia to bring patients briefly to uncon-
sciousness while the block was placed. Methohexital,
when given intravenously, has a rapid onset of sedation,
usually within 45 seconds depending on the circulation
time of the patient. Patients usually regain consciousness
within 3 minutes as the drug redistributes in the body.
After the block, patients in this study were lightly se-
dated for the remainder of the procedure, rarely requiring
additional sedation or analgesia. Midazolam and fentanyl
were used in the topical group. Midazolam, at the small
doses used in this study, provided anxiolysis in 3 to 5
minutes with duration of action as long as 2 hours. Fen-
tanyl, at the doses used in this study, provided analgesia
almost instantly with a maximal effect in 5 to 7 minutes
and a duration of action of 30 to 60 minutes. The small
doses of midazolam and fentanyl used in the topical
group left the patients lightly sedated yet awake and
cooperative. After placement of the block, the levels of
consciousness and the ability to adequately recall intra-
operative pain and discomfort levels postoperatively
were comparable between groups. Identical sedation pro-
tocols have been used in similar well-designed studies.7,8
A final concern is that patient pain levels were re-
corded postoperatively as opposed to intraoperatively.
Although intraoperative recording of pain is ideal, some
patients are reluctant to “complain” of pain during the
surgery, thus introducing a bias in the result. Conversely,
recording intraoperative pain levels postoperatively by
an independent observer allows for perhaps a more
J Glaucoma, Vol. 11, No. 4, 2002

314
N. A. ZABRISKIE ET AL.
acteristics, surgical management, and visual outcome. Ophthal-
mology 1991;98:519–26.
11. Sullivan KL, Brown GC Forman AL, et al. Retrobulbar anesthesia
and retinal vascular obstruction. Ophthalmology 1983;90:373–7.
12. Feibel RM. Current concepts in retrobulbar anesthesia. Surv Oph-
thalmol 1985;30:102–10.
13. Morgan CM, Schatz H, Vine AK, et al. Ocular complications
associated with retrobulbar injections. Ophthalmology 1988;95:
660–665.
14. Javitt JC, Addiego R, Friedberg BL, et al. Brainstem anesthesia
after retrobulbar block. Ophthalmology 1987;94:718–24.
15. Nicholl JM, Acharya PA, Ahlen K, et al. Central nervous system
complications after 6000 retrobulbar blocks. Anesth Analg 1987;
66:1298–302.
16. Jackson K, Vote D. Multiple cranial nerve palsies complicating
retrobulbar eye block. Anesth Intensive Care 1998;26:662–4.
17. Kaplan LJ, Jaffe NS, Clayman HM. Ptosis and cataract surgery. A
multivariant computer analysis of a prospective study. Ophthal-
mology 1985;92:237–42.
18. Rainin EA, Carlson BM. Postoperative diplopia and ptosis. A clini-
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19. Kimble JA, Morris RE, Witherspoon CD, Feist RM. Globe perfo-
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20. Bloomberg LB. Anterior periocular anesthesia: five years experi-
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accurate response. Furthermore, other indirect measures
of patient comfort recorded by the surgeon, such as pa-
tient cooperation and operative conditions, as conducted
in this study, can provide additional information of in-
traoperative pain levels.
Caution must be taken when using topical anesthesia
for patients with any communication difficulties. Addi-
tionally, mentally incompetent and very young or anx-
ious patients are obviously not good candidates. Further-
more, since all patients in this study had primary uncom-
plicated trabeculectomies, care is advised when
extrapolating these results to patients with previous con-
junctival surgery. In this study, the operating surgeon
was experienced with topical anesthesia and thus was
able to adjust to this modality for glaucoma surgery,
making minor adjustments in surgical approach and tech-
nique. However, as with any new technique, those not
accustomed to topical anesthesia may have a steeper
learning curve when adapting to this method.
In summary, both topical and retrobulbar anesthesia
provide equally efficacious optimal operative conditions
for the surgeon and excellent pain control for the patient.
However, topical anesthesia is a safer alternative to ret-
robulbar anesthesia for glaucoma surgery because it
eliminates many of the potential problems with injection
anesthesia.
21. Crandall AS, Zabriskie NA, Patel BCK, et al. A comparison of
patient comfort during cataract surgery with topical anesthesia
versus topical anesthesia and intracameral lidocaine. Ophthalmol-
ogy 1999;106:60–6.
22. Roman S, Auclin F, Ullern M. Topical versus peribulbar anesthesia
in cataract surgery. J Cataract Refract Surg 1996;22:1121–4.
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my. Ophthalmic Surg 1992;23:502–4.
24. Buys YM, Trope GE. Prospective study of sub-Tenon’s versus
retrobulbar anesthesia for inpatient and day-surgery trabeculecto-
my. Ophthalmology 1993;100:1585–9.
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