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comprasion of anesthetic efficacy and adverse effects associated with peribulbar injection of ropivacaine perfomed with and without ultrasound guidance in dogs

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1040 AJVR, Vol 75, No. 12, December 2014
Comparison of anesthetic efficacy and adverse 
effects associated with peribulbar injection 
of ropivacaine performed with and without 
ultrasound guidance in dogs
Juliana T. Wagatsuma, DVM, MSC; Maurício Deschk, DVM, MSC; Beatriz P. Floriano, DVM, MSC; 
Joana Z. Ferreira, DVM, MSC; Heitor Fioravanti, DVM; Isabela F. Gasparello, DVM; 
Valéria N. L. S. Oliva, DVM, PhD
Objective—To compare the anesthetic efficacy and adverse effects associated with per-
ibulbar injection of ropivacaine (1% solution) performed with and without ultrasound guid-
ance (UG) in dogs.
Animals—15 dogs without ophthalmologic abnormalities.
Procedures—Each dog was sedated and anesthetized. A peribulbar injection of ropivacaine 
(1% solution; 0.3 mL/kg) was performed with UG in 1 eye and without UG in the contralat-
eral eye (control). For each eye, the intraocular pressure (IOP) immediately after eye central-
ization and number of punctures were recorded; ophthalmic complications, postinjection 
corneal sensitivity (determined by Cochet–Bonnet esthesiometry), durations of the sensory 
and motor blockades (the latter determined as the interval to restoration of the vestibulo-
ocular reflex, pupillary light reflex, and conjugate eye movement), and blockade quality were 
assessed in both eyes following anesthetic recovery.
Results—Needle placement was fully visualized in 8 of the 15 eyes injected with UG. For 
eyes injected with or without UG, there was no difference with regard to the number of 
punctures, postinjection corneal sensitivity, and sensory or motor blockade duration and 
quality; however, restoration of conjugate eye movement occurred later in control eyes. For 
eyes injected with UG, mean IOP was 18.6 mm Hg, compared with 23.3 mm Hg for control 
eyes. Incidence of subconjunctival hemorrhage was higher for control eyes; severity of 
chemosis and hyperemia varied over time within both groups of eyes.
Conclusion and Clinical Relevance—In dogs, peribulbar injection of ropivacaine with UG 
is feasible in dogs and provides effective sensory and motor blockades similar to those 
achieved with conventional techniques. (Am J Vet Res 2014;75:1040–1048)
Received February 6, 2014.
Accepted June 9, 2014.
From the Department of Animal Clinic, Surgery and Reproduction, 
College of Veterinary Medicine of Araçatuba (FMVA), São Paulo 
State University (UNESP), Araçatuba, SP 16050-680, Brazil.
Funded by the Foundation for Research Support of the State of Sao 
Paulo (FAPESP).
Address correspondence to Dr. Wagatsuma (jutessalia@yahoo.com.
br).
To preserve ocular integrity, ophthalmic procedures require specialized anesthetic and surgical condi-
tions such as application of sophisticated equipment 
and techniques, patient immobilization, maintenance 
of cardiovascular and respiratory variables, and pro-
vision of an adequate surgical field.1 To achieve these 
conditions, intraocular analgesia should result in sen-
sory fiber blockade, ocular extrinsic muscle akinesia, 
oculocardiac reflex blockade, and reduced IOP,2 allow-
ing an appropriate postoperative outcome with mini-
mal opioid use.3
Retrobulbar and peribulbar blocks are highlighted 
among the various ophthalmic anesthetic techniques4 
such as intracameral5 and subtenonian6 injections, topi-
cal anesthesia, infiltrative anesthesia, and anesthesia of 
the lacrimal, zygomatic, ophthalmic, and auriculopal-
pebral nerves,4 because the isolated use of one of these 
techniques (except the subtenoniana injection) will 
provide only the sensorial or motor blockade, and the 
value of the cannula of Greenbaum used in subtenoni-
ana anesthesia technique can increase the cost of the 
procedure, which is high, compared with the cost of 
with peribulbar or retrobulbar blockade.7
For a retrobulbar block, the anesthetic agent is ad-
ministered within the retrobulbar musculature and re-
sults in adequate analgesia3 and globe akinesia; a small 
drug volume is required and yet the time to onset of 
effects is short.8 However, close contact of the needle 
ABBREVIATIONS
CEM Conjugate eye movement
IOP Intraocular pressure
PLR Pupillary light reflex
UG Ultrasound guidance
VOR Vestibulo-ocular reflex
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AJVR, Vol 75, No. 12, December 2014 1041
with the muscular cone is associated with several risks 
including intraneural anesthesia of the subarachnoid 
space, which may induce CNS depression, apnea, and 
cardiac arrest; IV administration; ocular puncture; and 
retrobulbar hemorrhage.9
As an alternative to the retrobulbar technique, 
peribulbar injection of anesthetic agents has been sug-
gested. In a peribulbar block, the needle is introduced 
parallel to the orbital wall or floor and, unlike the 
retrobulbar block, the anesthetic agent is delivered ex-
ternal to the muscular cone. Thus, a peribulbar block 
is considered a safer method10 because it reduces the 
risk of injury to the orbital structures such as the op-
tic nerve and blood vessels.a The peribulbar technique 
can be performed by double puncture at the orbit up-
per and lower corners11,a,b or by a single puncture at the 
inferotemporal or superonasal corner.12,a The needle 
puncture in the inferotemporal aspect is performed at 
a point situated on the border of the zygomatic arch at 
the junction between the lateral third and the medial 
two-thirds; a puncture in the superonasal corner is per-
formed between the medial third and the lateral two-
thirds.9,11 Results of several human14–17 and 2 animal12,a 
studies suggest that a single-puncture technique yields 
adequate drug distribution with a low incidence of oph-
thalmic complications.12 However, this technique usu-
ally requires a large volume of anesthetic agent as well 
as additional punctures when analgesia and akinesia 
were not adequate, which may increase the incidence 
of complications such as retrobulbar hematoma as well 
as scleral or ocular perforation.8,17,18
Ultrasound guidance during administration of an 
anesthetic agent enables real-time visualization of the 
needle and drug dispersion, thereby improving the 
quality and safety of the procedure.19 Widely used in 
human medicine20–23 and promisingly useful in vet-
erinary medicine for patients requiring local anesthe-
sia,24–31 anesthetic drug delivery with UG has advan-
tages over anesthetic drug delivery without UG. The 
benefits include reduced volume of anesthetic agent, 
improved therapeutic efficacy,25 and visual confirma-
tion of drug deposition.31–33
To our knowledge, the use of ultrasonography 
during application of ophthalmic anesthetic blocks 
has been rarely explored, with only a few reports31,33,34 
of human studies and 1 report19 of a study evaluating 
retrobulbar administration in equine cadavers. We are 
not aware of any studies of the efficacy and safety of an-
esthetic agents injected with UG for ocular anesthesia 
in live animals. On the basis of published data, use of 
UG during anesthetic agent administration to establish 
a peribulbar block could be a viable technique in dogs. 
Therefore, the purpose of the study reported here was 
to compare the anesthetic efficacy and adverse effects 
associated with peribulbar injection of ropivacaine (1% 
solution) performed with and without UG in dogs.
Materials and Methods
Animals—Fifteen adult dogs (30 eyes evaluated) 
owned by the university experimental kennel and of 
multiple breeds, both sexes, and various weights each 
underwent an ophthalmic examination. The evalua-
tions were performed in a specific sequence, as follows: 
tear production assessment (Schirmer tear testc); basal 
corneal sensitivity testing (basal esthesiometryd); eye-
lid, conjunctival, and corneal inspection (fluorescein 
stain teste) assisted by artificial light in a dark room; 
IOP measurement (applanationtonometryf); fundus 
evaluation (indirect ophthalmoscopyg); and ocular 
movement (VOR, PLR, and CEM). A CBC, serum bio-
chemical analysis, and general physical examination 
were also conducted.
The 15 animals included in the study had not un-
dergone ophthalmic surgical procedures and had no 
ophthalmic disorder; given that evaluation of only their 
healthy eyes was part of the study, none of those dogs 
was excluded or replaced. Dogs were excluded from the 
study if any abnormalities were evident on the initial 
examination. This study was conducted at the Faculty 
of Veterinary Medicine of UNESP, Campus of Araça-
tuba and was approved by the ethics committee of this 
institution, concerning the use of animals in animal 
experimentation.
Experimental procedures—Prior to each experi-
ment, food and water were withheld from each dog for 
12 and 2 hours, respectively. For sedation, aceproma-
zine maleateh was administered IM (0.05 mg/kg). After 
an interval of 20 minutes, a catheter was placed in a 
cephalic vein to enable IV administration of lactated 
Ringer’s solution (administration rate, 8 mL/kg/h). 
Anesthesia was induced with propofoli (5 mg/kg, IV) 
and maintained via inhalation of isofluranej in oxygen. 
Throughout the period that the dogs were anesthetized 
with isoflurane, heart and respiratory rates; esophageal 
temperature; systolic, diastolic, and mean arterial blood 
pressures; oxygen saturation as measured by pulse ox-
imetry; and fractions of inspired isoflurane and expired 
carbon dioxide were measured every 5 minutes with a 
multiparameter monitor.k
For each dog, the 2 eyelids (upper and lower) 
were shaved, and the puncture site was aseptically pre-
pared by delicately applying topical iodine solution 
with a sterile gauze. Each dog was first positioned in 
right recumbency for the peribulbar blockade with UG 
Figure 1—Photograph to illustrate transducer positioning relative 
to the upper eyelid and needle during peribulbar injection of a 
local anesthetic agent administered by a single puncture ventral 
to the orbit with UG in an isoflurane-anesthetized dog. The trans-
ducer orientation marker points toward the puncture site, and 
the transducer is angled 45° to 60° relative to the upper eyelid.
14-02-0030r.indd 1041 11/18/2014 1:32:09 PM
1042 AJVR, Vol 75, No. 12, December 2014
and thereafter in left lateral recumbency for peribulbar 
blockade without UG. Once the dog was stable under 
general anesthesia, the peribulbar block was performed 
with UGl via a single lower puncture site. Instead of a 
transcorneal technique, a trans-eyelid ultrasound tech-
nique was used to decrease the risk of corneal injury.35 
The transducer was positioned sagittally on the upper 
eyelid near the optical axis and angled 80° to 90° rela-
tive to the globe to allow identification of the eye, bul-
bar musculature, and optic nerve.
The transducer was then angled at 45° to 60° rela-
tive to the upper eyelid, remaining contralateral to the 
puncture point at the infraorbital floor and with the 
transducer orientation marker facing the puncture site 
(Figure 1); with this transducer orientation, the globe, 
ocular muscles, and optic nerve were simultaneously 
observed. Once the acoustic window was established, 
the needlem was introduced through the skin within 
the lateral third of the lower orbital margin and aligned 
lengthwise to the ultrasound beam, which allowed vi-
sual confirmation of the needle’s real-time peribulbar 
location. In this moment, a syringe with ropivacainen 
(1% solution; 0.3 mL/kg) was connected to the needle 
and the drug was administered and visualized during 
its deposition; the orbit was then gently compressed for 
2 minutes.
The dog was then positioned in lateral recumben-
cy on the other side of the body, and the axial length 
of that contralateral eye was measured; its extension 
was marked directly on the needle shank with a pen 
to avoid excessive insertion into the socket. The globe 
was anesthetized via injection of the same volume of 
ropivacaine used previously but drug administration 
occurred without UG (control eyes). The injection was 
performed solely on the basis of the peribulbar block 
anatomic landmarks, with the needlem introduced into 
the skin at the lower orbital margin between the lateral 
third and medial two-thirds. Once the drug was admin-
istered, the site was gently compressed for 2 minutes, 
the dog was kept in sternal recumbency for 20 minutes, 
and after this time, the anesthetic vaporization was 
completed.
Data collection—For both eyes in each dog, the 
number of punctures and the IOP immediately after eye 
centralization were recorded; for eyes injected with UG, 
the quality of needle visualization was assessed. Once 
the dog was completely awake (approx 30 minutes after 
the cessation of isoflurane administration), corneal and 
motor block durations and the incidence of ophthal-
mic complications were also determined. Each dog was 
evaluated every 30 minutes until the basal esthesiomet-
ric value return to baseline and ocular movement re-
turned and normalized. All dogs were evaluated by the 
same evaluators (FBP, JZF) who were unaware which 
eye was blocked with UG or not.
To assess the sensory blockade, corneal sensitiv-
ity was assessed with a Cochet–Bonnet esthesiometer; 
the filament length that induced a positive response 
indicated by a positive corneal reflex, globe retrac-
tion, or third eyelid protrusion in 2 of 3 consecutive 
assessments was recorded. A 4-cm-long filament was 
used initially, and the length was reduced in 0.5-cm 
increments for subsequent assessments until a positive 
response was elicited. To quantify the duration of the 
sensory blockade, the interval from the first evaluation 
after drug administration to when the esthesiometric 
value returned to the basal value was determined. The 
intensity of the motor blockade was considered absent, 
partial, or full on the basis of assessment of each of the 
cephalic movements: VOR (motor blockade indicated 
by absence of or decrease in lateral nystagmus during 
cranial rotation), PLR (motor blockade indicated by 
mydriasis unresponsive or poorly responsive to light), 
and CEM (motor blockade indicated by absence of or 
decreased visual accommodation during cranial move-
ment). The interval during which each cephalic move-
ment was not normal was recorded individually. Over-
all motor blockade duration was the time needed for 
the motor blockades to become absent as determined 
on the basis of the VOR, PLR, and CRM.
Each dog’s eyes were assessed for ophthalmic com-
plications. Hyperemia, chemosis, subconjunctival hem-
orrhage, ophthalmic pruritus, tearing, and discharge 
were classified as absent, light, moderate, or intense; 
the behavior of these complications over the time was 
assessed. For statistical analysis, the severities of the 
ocular complications detected at 30, 60, 180, and 300 
minutes after injection of the anesthetic agent and the 
last moment evaluated were also used. However, be-
cause the timing of that last evaluation differed among 
individuals, the final evaluation time point was not the 
same for all dogs.
Statistical analysis—Data that were not normally 
distributed or had a high variation coefficient were 
compared with the Wilcoxon test; normally distributed 
data were compared with a paired t test. Comparisons 
over time within each group of eyes were analyzed with 
the Friedman test, followed by the Dunn test for mul-
tiple comparisons. Comparisons over time between 
the groups of eyes were performed with the Wilcoxon 
signed rank test. The data were analyzed with computer 
softwareo; a value of P < 0.05 was considered significant.
Results
Fifteen dogs were selected and included in the 
study. There were 8 females and 7 males of various 
breeds, includingBeagle (n = 8), Labrador Retriever 
(1), Golden Retriever (1) and mixed-breed dogs (5). 
The mean ± SD weight was 13.5 ± 10.9 kg (median, 
8.3 kg). During anesthesia, all dogs maintained mean 
arterial blood pressure (63.2 ± 5.4 mm Hg) within ref-
erence range, and fraction of expired carbon dioxide 
was 40.5 ± 5.6 mm Hg.
The peribulbar block was successfully performed 
in both eyes of all dogs. To correctly execute the injec-
tion with UG, an adequate acoustic window allowing 
real-time visualization of the needle, globe, and mus-
culature was required. The needle was appropriately 
positioned in the peribulbar region of the 15 eyes. In 8 
of the 15 eyes, complete ultrasonographic visualization 
of the needle was achieved; the needle shank and tip 
were partially visible in images obtained from 4 eyes. 
The needle tip only was ultrasonographically visible 
for 3 eyes. Tissue distortion or the needle shank alone 
was not observed in the images for any of the 15 eyes. 
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AJVR, Vol 75, No. 12, December 2014 1043
The ropivacaine deposition was completely visualized 
in real time in all 15 eyes, and both the hypoechoic and 
anechoic aspects were visible as circular or oval shapes 
(Figure 2). After peribulbar injection of ropivacaine 
with UG, centering of the pupil was visible (Figure 3). 
Of the variables assessed, only data for the IOP mea-
surements were normally distributed, and are reported as 
mean ± SD. All other data were not normally distributed, 
and were compared by means of the Wilcoxon test; these 
data are reported as median and range as well as mean ± 
SD.
For eyes that received a ropivacaine injection with 
UG, sensory block duration, the value of corneal esthe-
siometry obtained in the first assessment after admin-
istration of the anesthetic agent, and the mean number 
of punctures did not differ from findings for eyes that 
received a ropivacaine injection without UG (Table 1). 
For eyes injected with and without UG, the intervals 
during which the VOR, PLR, and CEM were absent and 
the intervals during which the VOR, PLR, and CEM 
were decreased did not differ significantly (Table 2). 
There was no difference in the intervals to restoration of 
the VOR and PLR; however, the interval to restoration 
of the CEM differed significantly between the groups of 
eyes. There was no difference in the overall duration of 
motor block between the groups of eyes.
The mean basal IOP was 18.8 ± 3.5 mm Hg in the 
eyes that were subsequently injected without UG and 
19.6 ± 4.2 mm Hg in the eyes that were subsequently 
injected with UG. After ropivacaine injection, mean 
IOP immediately after eye centralization) differed sig-
nificantly (P < 0.05) between the 2 groups of eyes (23.3 
± 5.2 mm Hg in the control eyes vs 18.6 ± 5.4 mm Hg in 
the eyes injected with UG). The mean IOP immediately 
after eye centralization differed significantly (P < 0.05) 
from the basal value for the control eyes.
The dogs’ eyes were assessed for development of 
hyperemia, chemosis, subconjunctival hemorrhage, 
ophthalmic pruritus, tearing, and discharge (all of 
which were classified as absent, light, moderate, or in-
tense) at 30, 60, 180, and 300 minutes after injection of 
the anesthetic agent and at the final evaluation (Table 
3). In the eyes that received a ropivacaine injection with 
UG, chemosis was evident in all dogs 30 minutes after 
administration of the anesthetic agent. However, the 
classification assigned to this complication decreased 
over time and differed significantly at 60 and 300 min-
utes and at the final assessment after administration of 
the anesthetic agent; the severity at 60 minutes after 
injection of ropivacaine also differed from that at 300 
minutes and at the final evaluation. Among eyes that 
received ropivacaine injection, that of only 1 dog did 
not develop chemosis at 30 minutes after administra-
tion of the anesthetic agent; this finding differed with 
changes identified at 60, 180, and 300 minutes and at 
Figure 2—Representative real-time ultrasonographic image of 
the dispersion (area outlined by yellow dots) of 1% ropivacaine 
solution after peribulbar administration with UG in an isoflurane-
anesthetized dog. In this image, the needle (arrow), globe (G), 
and optic nerve (ON) are visible.
Figure 3—Photographs illustrating ocular rotation (right eye) be-
fore peribulbar injection of 1% ropivacaine solution (A) and the 
visible centering of the pupil (left eye) after peribulbar injection of 
ropivacaine with UG (B) in an isoflurane-anesthetized dog.
 Peribulbar injection technique
 With UG Without UG
Variable Median (range) Mean ± SD Median (range) Mean ± SD
No. of punctures 1 (1–3) 1.5 ± 0.7 1 (1–6) 1.7 ± 1.3
Duration of sensory blockade (min) 383 (212–732) 416 ± 138.9 383 (157–485) 352.8 ± 97.7
Basal esthesiometric value (cm) 1.5 (2.0–2.5) 1.6 ± 0.47 1 (1–3) 1.4 ± 0.57
Postinjection esthesiometric value (cm) 0 (0–1) 0.066 ± 0.25 0 (0–0.05) 0.033 ± 0.12
Basal (pretreatment) corneal sensitivity testing of each dog was performed by use of a Cochet-Bonnet 
esthesiometer (pretreatment esthesiometric value [baseline]). Each dog underwent inhalation anesthesia 
with isoflurane and was administered a peribulbar injection of ropivacaine bilaterally (injection performed 
with UG for 1 eye and without UG for the other eye). A trans-eyelid ultrasonographic technique was used to 
decrease the risk of corneal injury, compared with the risk associated with a transcorneal technique. Number 
of punctures required to perform each injection was recorded. On completion of study evaluations, each dog 
was allowed to recover from anesthesia. Once the dog was completely awake (approx 30 minutes after gen-
eral anesthetic recovery), corneal sensitivity was reassessed by esthesiometry (postinjection esthesiometric 
value). Duration of sensory blockade was calculated as the interval from the first assessment to the last as-
sessment at which the esthesiometric value returned to baseline.
Table 1—Data obtained for 15 dogs that received a peribulbar injection of ropivacaine (1% solution; 0.3 
mL/kg) with UG in 1 eye and without UG in the contralateral eye (control).
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1044 AJVR, Vol 75, No. 12, December 2014
the final evaluation, and the classification at 60 min-
utes of administration differed with that assessed at 180 
or 300 minutes and at the final evaluation. Severity of 
hyperemia also varied between the groups, but owing 
 Peribulbar injection technique
 With UG Without UG
Variable Median (range) Mean ± SD Median (range) Mean ± SD
VOR
 Full blockade (min) 33 (0–70) 26.3 ± 21.8 28 (0–60) 24.9 ± 17.9
 Partial blockade (min) 15 (0–60) 26.7 ± 23.5 15 (0–90) 30.3 ± 27.4
 Overall blockade (min) 45 (0–168) 53.8 ± 40.2 41 (0–108) 48.8 ± 29.2
PLR
 Full blockade (min) 348 (98–630) 375.3 ± 124.6 313 (0–650) 323.8 ± 167.4
 Partial blockade (min) 30 (0–90) 42 ± 31.7 30 (0–150) 44 ± 39.1
 Overall blockade (min) 360 (158–690) 381 ± 146.1 400 (0–840) 390.5 ± 194.5
CEM
 Full blockade (min) 35 (0–70) 31.6 ± 20 25 (0–60) 24 ± 18.3
 Partial blockade (min) 15 (0–60) 25.3 ± 21.3 15 (0–105) 26.5 ± 29.8
 Overall blockade (min) 43* (0–98) 52.3 ± 27.7 50* (0–103) 55.7 ± 28.6
To assess motor blockade after peribulbar injection of ropivacaine in each eye, the intervals during which the 
VOR, PLR, and CEM were absent (full blockade) or decreased (partial blockade) were recorded. For the VOR, this 
was indicated by absence of or decrease in lateral nystagmus during cranial rotation. For the PLR, this was indicat-
ed by mydriasis that was unresponsive or poorly responsive to light. For CEM, this was indicated by absence of ordecrease in visual accommodation during cranial movement. Overall duration of motor blockade was calculated as 
the interval from the first assessment with the dog completely awake (approx 30 minutes after general anesthetic 
recovery) to the last assessment when eye movement returned and was normalized.
 *For this variable, values differ significantly (Wilcoxon test, P < 0.02) between groups)
Table 2—Duration of ocular motor blockade (determined on the basis of full or partial blockade of the 
VOR, PLR, and CEM) in the 15 dogs in Table 1 that received a peribulbar injection of ropivacaine (1% 
solution; 0.3 mL/kg) with UG in 1 eye and without UG in the contralateral eye (control).
 Peribulbar injection technique
 With UG Without UG
 30 60 180 300 30 60 180 300 
Complication and severity minutes minutes minutes minutes Final Total minutes minutes minutes minutes Final Total
Hyperemia 12 13
 Absent 4 4 3 4 4 5 5 3 4 4 
 Light 4 5 3 5 6 5 6 3 4 6 
 Moderate 7 6 8 6 5 5 4 7 7 5 
 Intense 0 0 1 0 0 0 0 2 0 0 
Chemosis 15 14
 Absent 0 0 0 4 6 2 1 1 3 6 
 Light 2 2 8 9 8 2 2 8 10 8 
 Moderate 8 7 7 2 1 7 6 6 2 1 
 Intense 5 6 0 0 0 4 6 0 0 0 
Subconjunctival hemorrhage 3 8
 Absent 13 13 14 13 13 9 8 8 8 9 
 Light 2 2 1 2 2 3 4 3 5 4 
 Moderate 0 0 0 0 0 1 0 3 2 2 
 Intense 0 0 0 0 0 2 3 1 0 0 
Ophthalmic pruritus 1 1
 Absent 15 15 14 15 15 15 15 14 15 15 
 Light 0 0 1 0 0 0 0 1 0 0 
 Moderate 0 0 0 0 0 0 0 0 0 0 
 Intense 0 0 0 0 0 0 0 0 0 0 
Tearing 1 1
 Absent 14 14 14 15 15 15 15 13 15 15 
 Light 1 1 1 0 0 0 0 2 0 0 
 Moderate 0 0 0 0 0 0 0 0 0 0 
 Intense 0 0 0 0 0 0 0 0 0 0 
Discharge 3 3
 Absent 15 14 14 15 15 14 14 14 15 15 
 Light 0 1 1 0 0 1 1 1 0 0 
 Moderate 0 0 0 0 0 0 0 0 0 0 
 Intense 0 0 0 0 0 0 0 0 0 0 
Each dog’s eyes were assessed for ophthalmic complications; hyperemia, chemosis, subconjunctival hemorrhage, ophthalmic pruritus, 
tearing, and discharge were classified as absent, light, moderate, or intense. The severity of the ocular complications was recorded at 30, 60, 
180, and 300 minutes after injection of the anesthetic agent and at the last moment evaluated. However, because the timing of that last evaluation 
differed among individuals, the final evaluation time point was not the same for all dogs. The number of complications does not add up to the total 
number because statistical analyses were only performed with the values obtained at 30, 60, 180, and 300 minutes after injection; these time points 
were chosen because they were associated with a greater number of variations. Only the incidence of subconjunctival hemorrhage differed 
significantly (P = 0.031) between the 2 groups of eyes, with a higher incidence in the control group.
Table 3—Number of eyes with ophthalmic complications at various time points in the 15 dogs in Table 1 that received a peribulbar 
injection of ropivacaine (1% solution; 0.3 mL/kg) with UG in 1 eye and without UG in the contralateral eye (control).
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AJVR, Vol 75, No. 12, December 2014 1045
to the low magnitude of severity difference on the basis 
of the Dunn multiple comparison test, the intragroup 
variation over time could not be determined. Only the 
incidence of subconjunctival hemorrhage (Figure 4) 
differed significantly (P = 0.031) between the 2 groups 
of eyes, with a higher incidence in the control group.
In 3 large dogs, (1 Labrador Retriever, 1 Golden 
Retriever, and 1 mixed-breed dog), the ultrasonograph-
ic images were poor quality in both eyes, and eyeballs 
were somewhat retracted after the beginning of inha-
lation anesthesia; however, these facts did not prevent 
the completion of the blocks and did not necessitate 
removal of the images from the study. The tear pro-
duction was not measured after ropivacaine injection 
performed with UG and without UG but was visibly 
decreased during the measurement of the IOP, sensory 
evaluations, and assessment of ophthalmic complica-
tions in both eyes in all dogs.
Punctate superficial ulcers were found in 2 of these 
dogs in both eyes, in the central part of the cornea at the 
final assessments, though no signs of discomfort were 
observed. The dogs were administered topical anti- 
inflammatory eye dropsp and an antimicrobial ophthal-
mic solutionq every 6 hours as long as was necessary; 
however, the corneas were healed after 3 days.
Discussion
Ultrasound-guided administration of local anes-
thetic agents has received great notoriety in human 
and veterinary medicine.19 However, few studies29 have 
compared the clinical outcomes of these techniques 
with those of anesthetic blocks applied on the basis of 
anatomic landmarks in live animals.19,30 Thus, the pres-
ent study has provided pioneering results through com-
parison of data obtained following peribulbar injection 
of ropivacaine (1% solution) performed with and with-
out UG in dogs.
Successful peribulbar injection of an anesthetic 
agent with UG depends on upper trans-eyelid position-
ing of the transducer, visualization of the needle and 
orbital structures, and real-time observation of the drug 
dispersion. The few published reports19,31,32 of ophthal-
mic blocks applied with UG describe the importance of 
these criteria to ensure a positive clinical outcome.
Although we decided to use a high fixed volume 
of ropivacaine to ensure that the techniques were not 
affected by low drug volumes (given that the local 
structures [extraocular muscles, fat, and blood vessels] 
could alter its dispersion into the intraconal36 region), 
benefits provided by local blocks administered with 
UG, such as reducing the volume and latency of the an-
esthetic agent24,25,28 were not evaluated. However, other 
advantageous features related to the blocks adminis-
tered with UG were observed including increased safety 
for the patient, visual confirmation of drug deposition, 
objective technical accuracy, and increased efficiency 
for difficult blocks.19,25,26,30
The lack of significant differences in sensory and 
motor blockade duration in the eyes anesthetized with 
or without UG was due to the use of ropivacaine in the 
same concentration (1%) and volume (0.3 mL/kg). In 
the dogs’ eyes evaluated in the present study, the senso-
ry blockade duration was longer than the motor block-
ade duration (attributed to due to the higher affinity 
of Aδ and C sensory fibers for ropivacaine, compared 
with that of motor fibers37). This finding was similar to 
a previously reported sensory blockade duration of 360 
minutes in dogs that received local anesthesia of 1% 
ropivacaine solution.38 However, these data differ from 
that reported by Oliva et al,11 who recorded a 272-min-
ute sensory blockade duration in dogs administered a 
less concentrated ropivacaine formulation (0.75%) via 
peribulbar injection. Vasquez et al40 observed a greater 
efficacy of 1% ropivacaine solution, compared with that 
of 0.75% ropivacaine solution, after periconal injection 
in humans. Lidocaine administration by sub-Tenonian 
peribulbar injection in dogs undergoing phacoemulsifi-
cation provided analgesia of approximately 88 minutes’ 
duration in another report.6 Results of these studies 
confirm that ropivacaine has a long duration of action, 
compared with other local anesthetic agents and may 
reduce the pre- and postoperative opioid analgesic re-
quirement and consequently, reduce the opioid-asso-
ciated adverse effects (eg, sedation, urinary retention, 
vomiting, and body temperature changes40).
Esthesiometric values between 0 and 0.5 cm indi-
cate corneal insensitivity in dogs11; the values for the 
dogs’ eyes evaluated in the present study were within 
this range, thereby confirming the effectiveness of the 
injection techniques. The esthesiometricvalues were 
unlikely to have been influenced by anesthesia. The 
assessment was performed approximately 30 minutes 
after recovery from anesthesia (when the dogs were 
conscious) and the esthesiometric response remained 
absent for hours, gradually returning to basal status in 
nearly all dogs. These findings all confirm the establish-
ment of an effective sensory blockade.
The motor blockade of the PLR was the most in-
tense and lasting motor effect in both eyes in all dogs 
in the present study, which differs from the findings 
of a study by Klaumanna in which a partial total mo-
tor blockade of the PLR was detected in approximately 
60% of 15 dogs at 55 minutes after peribulbar injection 
of 1% ropivacaine solution and partial motor block-
ade was decreased in 40% of the dogs at 100 minutes; 
the difference between the values in intensity and du-
ration of motor blockade in this study and in that by 
Klaumanna can be explained by the low volume (0.1 
mL/kg) of anesthetic agent used in the latter, and also 
by the administration of the total volume of ropiva-
caine between 2 points of puncture (lateral corner and 
nasomedial aspect), which exposed the parasympathet-
ic nerve fibers to a lower amount of anesthetic agent. 
Figure 4—Photographs illustrating development of chemosis (left 
eye) after peribulbar injection of 1% ropivacaine solution with UG 
(A) and subconjunctival hemorrhage (right eye) after peribulbar 
injection of ropivacaine without UG (B) in an isoflurane-anesthe-
tized dog.
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1046 AJVR, Vol 75, No. 12, December 2014
The high-quality mydriasis induced by techniques in 
the present study eliminated the need for intraoperative 
administration of mydriatic eye drops, which requires 
comparatively more time to achieve the desired effect. 
Pupillary dilation induced by mydriatics eye drops of-
ten dissipates during surgery41,42 and is limited when 
uveitis is present.43
In the present study, the duration of the motor 
blockade achieved by peribulbar injection of ropivacaine 
was short, and the blockade was predominantly partial of 
the VOR and CEM reflexes. Oliva et al11 detected a motor 
blockade of 133 minutes’ duration after peribulbar injec-
tion of ropivacaine 0.75% in dogs undergoing facectomy, 
but the method of assessment was period intraoperative 
measurement of the ocular rotation by a goniometer, 
which differed from the evaluation method used in the 
present study. Klaumanna reported partial motor block-
ade of the VOR in 9 of 15 dogs only at 100 minutes af-
ter peribulbar injection of 1% ropivacaine solution. In 
the present study, the difference in CEM between eyes 
that were injected with or without UG was 3.4 minutes, 
which was not considered clinically relevant. Eye cen-
tralization can also be achieved through neuromuscular 
blockade, but those neuromuscular agents are associated 
with respiratory muscle paralysis and require controlled 
ventilation as well as adequate patient monitoring.8,43
In humans, IOP increases in response to extra-
ocular muscle pressure, intraocular content changes,45 
systemic hypertension, medications, and hypercapnia. 
All dogs of the present study maintained mean arterial 
blood pressure (63.2 ± 5.4 mm Hg) within reference 
range, and fraction of expired carbon dioxide was 40.5 
± 5.6 mm Hg; the drugs administered are known to re-
duce or maintain IOP,46,47 and a change in intraocular 
fluid volume was unlikely because no intraocular drug 
administration was evident.
In humans, IOP may transiently increase immedi-
ately following the peribulbar injection because of the 
pressure exerted on the globe by the physical volume of 
drug injected, which increases intraorbital pressure.48 
Differences in IOP found between the groups may be 
due to the large volume of injected anesthetic agent 
and of the inadequate extrinsic muscle relaxation in 
some animals. Ideally, IOP should be evaluated serially 
during the period of blockade to determine whether 
any increase is transitory and related to the high drug 
volume or related to high latency of the block because 
the peribulbar technique is subject to inaccurate nee-
dle positioning when performed without UG. Luyet et 
al33 observed the real-time dispersion of lidocaine af-
ter performing a peribulbar block without UG in hu-
mans and found erroneous intraconal dispersion in 61 
of 100 subjects. In the dogs’ eyes that received ropi-
vacaine injection with UG, IOP was unchanged after 
the procedure, because of the ability of ropivacaine to 
reduce IOP11,48,49,b; this ability may assist in balancing 
the IOP when large volumes of anesthetic agents are 
administered, increasing suspicions that the technique 
of peribulbar injection without UG directly influences 
IOP value as a result of inappropriate placement of the 
needle.
Ophthalmic complications may be associated 
with peribulbar injections of local anesthetic agents 
and include pruritus, blepharospasm, chemosis, and 
subconjunctival hemorrhage6; administration of retro-
bulbar blocks may cause hyperemia and corneal ulcer-
ation.8 In the present study, subconjunctival hemor-
rhage was less common and less intense in the dogs’ 
eyes that received the ropivacaine injection with UG, 
compared with findings for eyes that received the rop-
ivacaine injection without UG, likely because of more 
accurate orientation of the needle path. Chemosis is 
caused by drug dispersion in the anterior orbit,44,50 
and decreases over time as the anesthetic agent is 
absorbed. Accola et al18 reported that hyperemia was 
associated with excessive conjunctival manipulation 
during motor blockade assessment after performing a 
retrobulbar block in dogs. In the present study, senso-
ry evaluation was frequently only possible by forcing 
the eyelids open manually, causing excessive conjunc-
tival manipulation. Abnormal lacrimal production51 
and eyelid akinesia5 may cause hyperemia, ocular dis-
charge, and corneal ulceration in dogs; although these 
complications were not assessed during the postinjec-
tion period in the present study, they were observed in 
some dogs, confirming the potential risk of ophthal-
mic complications.
The lower-quality definition of images obtained for 
3 large dogs in the present study may be attributable to 
bulbar retraction caused by propofol- and isoflurane-
induced muscle relaxation.52 According to Spaulding,51 
ocular ultrasonography is more difficult in large dogs 
because of globe retraction; however, this does not con-
traindicate the use of UG during administration of ocu-
lar anesthetic blocks.
A limitation of the present study was that the tear 
film in each eye was not evaluated after the injection 
had been administered. However, tear production was 
visibly decreased during the measurement of the IOP, 
sensory evaluations, and assessment of ophthalmic 
complications in both eyes in all dogs. Yasui et al53 
demonstrated a relationship between lacrimal gland va-
sodilation (induced by electrical corneal stimulation) 
and tear production in cats, which was mediated by 
the ophthalmic nerve via the parasympathetic pathway. 
The vasoconstrictive effect of ropivacaine54 may reduce 
lacrimal gland perfusion, which, when combined with 
an efficient sensory block (ophthalmic nerve block), 
may explain the decreased tear film in the study dogs. 
The anesthetic blockade of lacrimal gland innervation 
cannot be ruled out because of the dorsolateral location 
of the gland within the orbit.55
Results of the present study indicated that peri- 
bulbar injection of anesthetic agents can be performed 
effectively with UG in dogs. Use of upper trans-eyelid 
transducer positioning allowed real-time needle visu-
alization and anesthetic agent dispersion. The quality 
and duration of the sensory and motor blockades werevery similar to those obtained by the conventional per-
ibulbar injection technique (without UG). However, 
the eyes of the dogs that received peribulbar injec-
tion performance with UG, the IOP remained stable 
and the incidence of subconjunctival hemorrhage was 
lower, highlighting the need for further studies to as-
sess the potential clinical usefulness of this anesthetic 
technique.
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AJVR, Vol 75, No. 12, December 2014 1047
a. Klauman PR. Bloquio peribulbar com ropivacaina 1% em cães. 
MS dissertation. Universidade Federal do Paraná, Cuitiba, PR, 
Brazil, 2007.
b. Ferreira JZ. Bloqueio peribulbar com ropivacaína a 0.75% para 
facectomia em cães: padronização e comparação de técnicas. MS 
dissertation, Faculdade de Odontologia, Universidade Estadual 
Paulista, Araçatuba, Brazil, 2011.
c. Schirmer reflex test, Ophthalmos Indústria e Comércio de 
Produtos Farmacêuticos LTDA, São Paulo, Brazil.
d. Cochet & Bonnet esthesiometer, Luneau Ophtalmologie, Char-
tres, France.
e. Fluorescein strips, Ophthalmos Indústria e Comércio de Produ-
tos Farmacêuticos LTDA, São Paulo, Brazil.
f. Tono-Pen XL, Medtronic, Jacksonville, Fla.
g. Bio Welch Allyn, Welch Allyn, Skaneateles Falls, NY.
h. Acepran 0.2%, Vetnil Ind e Comer de Produtos Veterinários 
LTDA, São Paulo, Brazil.
i. Propovan, Cristália Produtos Químicos e Farmacêuticos, São 
Paulo, Brazil.
j. Isoforine, Cristália Produtos Químicos e Farmacêuticos, São 
Paulo, Brazil.
k. Monitor, Cardiocap 5, Datex-Ohmeda, GE Healthcare Indus-
tries, São Paulo, Brazil.
l. Accutome B-Scan Plus Advanced, Probe B: 15 MHz, resolution: 
0.015 mm, gain: 47 e 55 dB, Accutome, Malvern, Pa.
m. Agulha hipodérmica 22-gauge 1” BD PrecisionGlide, Becton 
Dickinson Ind. Cirúrg. LTDA, Curitiba, Brazil.
n. Ropivacaine 1%, Cristália Produtos Químicos e Farmacêuticos, 
São Paulo, Brazil.
o. SAS, version 9.3, SAS Institute Inc, Cary, NC.
p. Cetorolaco de Trometamol 0.5%, Allergan, São Paulo, Brazil.
q. Tobramicina, Alcon, São Paulo, Brazil.
References
1. Carareto R, Nunes N, Sousa MG, et al. Anesthesia for oph-
thalmic surgeries in canines. Rev Port Cienc Veterinarias 
2007;102:35–42.
2. Vanetti LFA. Anestesia para oftalmologia. In: Ortenzi AV, 
Tardelli MA, eds. Anestesiologia – Sociedade de Anestesiologia do 
Estado de São Paulo. São Paulo, Brazil: Atheneu, 1996;591–606.
3. Myrna KE, Bentley E, Smith LJ. Effectiveness of injection of lo-
cal anesthetic into the retrobulbar space for postoperative an-
algesia following eye enucleation in dogs. J Am Vet Med Assoc 
2010;237:174–177.
4. Kahvegian MP. Cirurgia ocular. Técnicas de Anestesia local. In: 
Fantoni DT, Cortopassi SRG, eds. Anestesia em cães e gatos. 2nd 
ed. São Paulo, Brazil: Editora Rocca, 2010;319–332.
5. Park SA, Park YW, Son WG, et al. Evaluation of the analgesic 
effect of intracameral lidocaine hydrochloride injection on in-
traoperative and postoperative pain in healthy dogs undergoing 
phacoemulsification. Am J Vet Res 2010;71:216–222.
6. Ahn J, Jeong M, Lee E, et al. Effects of peribulbar anesthesia 
(sub-Tenon injection of a local anesthetic) on akinesia of extra-
ocular muscles, mydriasis, and intraoperative and postoperative 
analgesia in dogs undergoing phacoemulsification. Am J Vet Res 
2013;74:1126–1132.
7. Barreiro J, Barreiro TP, Rehder JRCL. Costs of local anesthesia 
technique used in ophthalmology to perform cataract surgery 
by phacoemulsification. Arq Bras Oftalmol 2004;67:51–67.
8. Cyriac IC, Pineda RII. Postoperative complications of periocu-
lar anesthesia. Int Ophthalmol Clin 2000;40:85–91.
9. Gross EM, Giuliano EA. Anesthesia for special patients: ocular 
patients. In: Thurmon JC, Tranquilli WJ, Benson GJ, eds. Lumb 
& Jones’ veterinary anaesthesia and analgesia. 4th ed. Baltimore: 
Williams & Wilkins, 2007;943.
10. Shilo-Benjamini Y, Pascoe PJ, Maggs DJ, et al. Retrobulbar and 
peribulbar regional techniques in cats: a preliminary study in 
cadavers. Vet Anaesth Analg 2013;40:623–631.
11. Oliva VNLS, Andrade AL, Bevilacqua L, et al. Anestesia peribul-
bar com ropivacaína como alternativa ao bloqueio neuromuscu-
lar para facectomia em cães. Arq Bras Med Vet Zoo 2010;62:586–
595.
12. Demirok A, Simsek S, Cinal A, et al. Peribulbar anesthesia: one 
versus two injections. Ophthalmic Surg Lasers 1997;28:998–
1001.
13. El Said TM, Kabeel MM. Comparison of classic peribulbar anes-
thesia and new entry point (single percutaneous injection tech-
nique) in vitroretinal surgery. Saudi J Anaesth 2010;4:80–85.
14. Ghali AM, Hafez A. Single-injection percutaneous peribulbar 
anesthesia with a short needle as an alternative to the dou-
ble-injection technique for cataract extraction. Anesth Analg 
2010;110:245–247.
15. Nouvellon E, Cuvillon P, Ripart J, et al. Anaesthesia for cataract 
surgery. Drugs Aging 2010;27:21–38.
16. Edge R, Navon S. Scleral perforation during retrobulbar and 
peribulbar anesthesia: risk factors and outcome in 50,000 con-
secutive injections. J Cataract Refract Surg 1999;25:1237–1244.
17. Ripart J, Lefrant JY, De La Coussaye JE, et al. Peribulbar versus 
retrobulbar anesthesia for ophthalmic surgery: an anatomical 
comparison of extraconal and intraconal injections. Anesthesiol-
ogy 2001;94:156–62.
18. Accola PJ, Bentley E, Smith LJ, et al. Development of a retrobul-
bar injection technique for ocular surgery and analgesia in dogs. 
J Am Vet Med Assoc 2006;229:220–225.
19. Morath U, Luyet C, Spadavecchia C, et al. Ultrasound-guided 
retrobulbar nerve block in horses: a cadaveric study. Vet Anaesth 
Analg 2013;40:205–211.
20. Perlas A, Chan VW, Simons M. Brachial plexus examination and 
localization using ultrasound and electrical stimulation: a vol-
unteer study. Anesthesiology 2003;99:429–435.
21. Spence BC, Sites BD, Beach ML. Ultrasound-guided musculo-
cutaneous nerve block: a description of a novel technique. Reg 
Anesth Pain Med 2005;30:198–201.
22. Casati A, Baciarello M, Di Cianni S, et al. Effects of ultrasound 
guidance on the minimum effective anaesthetic volume required 
to block the femoral nerve. Br J Anaesth 2007;98:823–827.
23. Tran TMN, Ivanusic JJ, Hebbard P, et al. Determination of spread 
of injectate after ultrasound-guided transversus abdominis 
plane block: a cadaveric study. Br J Anaesth 2009;102:123–127.
24. Costa-Farré C, Blanch XS, Cruz JI, et al. Ultrasound guidance 
for the performance of sciatic and saphenous nerve blocks in 
dogs. Vet J 2011;187:221–224.
25. Campoy L, Bezuidenhout AJ, Gleed RD, et al. Ultrasound-guid-
ed approach for axillary brachial plexus, femoral nerve, and sci-
atic nerve blocks in dogs. Vet Anaesth Analg 2010;37:144–153.
26. Schroeder CA, Snyder LBC, Tearney CC, et al. Ultrasound-guid-
ed transversus abdominis plane block in the dog: an anatomical 
evaluation. Vet Anaesth Analg 2011;38:267–271.
27. Mahler SP. Ultrasound guidance to approach the femoral nerve 
in the iliopsoas muscle: a preliminary study in the dog. Vet An-
aesth Analg 2012;39:550–554.
28. Echeverry DF, Laredo FG, Gil F, et al. Ultrasound-guided ‘two-
in-one’ femoral and obturator nerve block in the dog: an ana-
tomical study. Vet Anaesth Analg 2012;39:611–617.
29. da Cunha AF, Strain G, Rademacher N, et al. Palpation and ul-
trasound-guided brachial plexus blockade in Hispaniolan Ama-
zon parrots (Amazona ventralis). Vet Anaesth Analg 2013;40:96–
102.
30. De Vlamynck CA, Pille F, Hauspie S, et al. Evaluation of three 
approaches for performing ultrasonography-guided anes-
thetic blockade of the femoral nerve in calves. Am J Vet Res 
2013;74:750–756.
31. Luyet C, Eichenberger U, Moriggl B, et al. Real-time visualiza-
tion of ultrasound-guided retrobulbar blockade: an imaging 
study. Br J Anaesth 2008;101:855–859.
32. Lundblad M, Eksborg S, Lonnqvist PA. Secondary spread ofcaudal block as assessed by ultrasonography. Br J Anaesth 
2012;108:675–681.
33. Luyet C, Eng KT, Kertes PJ, et al. Real-time evaluation of dif-
fusion of the local anesthetic solution during peribulbar block 
using ultrasound imaging and clinical correlates of diffusion. 
Reg Anesth Pain Med 2012;37:455–459.
34. Palte HD, Gayer S, Arrieta E, et al. Are ultrasound-guided oph-
thalmic injurious to the eye? A comparative rabbit model study 
of two ultrasound devices evaluating intraorbital thermal and 
structural changes. Anesth Analg 2012;115:194–201.
35. Mattoon J, Nyland TG. Olho. In: Ultra-som diagnóstico em 
14-02-0030r.indd 1047 11/18/2014 1:32:13 PM
1048 AJVR, Vol 75, No. 12, December 2014
pequenos animais. 2nd ed. São Paulo: Editora Roca, 2005;317–
321.
36. Nouvellon E, Cuvillon P, Ripart J. Regional anesthesia and eye 
surgery. Anesthesiology 2010;113:1236–1242.
37. Feldman HS, Covino BG. Comparative motor-blocking effects 
of bupivacaine and ropivacaine, a new amino amide local 
anesthetic, in the rat and dog. Anesth Analg 1988;67:1047–
1052.
38. Cortopassi SRG, Fantoni DT. Anestésicos locais. In: Andrade SF. 
Manual de terapêutica veterinária. 2nd ed. São Paulo, Brazil: Edi-
tora Roca LTDA, 2010;375.
39. Vásquez CE, Macuco MV, Bedin A, et al. Comparação da Quali-
dade do Bloqueio Oftálmico Periconal com Ropivacaína a 1% e 
0,75% com Punção nos Pontos Infraorbitário Lateral e Medial 
da Órbita. Rev Bras Anestesiol 2002;52:681–688.
40. Plumb DC. Morphine sulfate. In: Plumb’s veterinary drug hand-
book. 6th ed. Stockholm,Wis: PharmaVet, 2008;632–634.
41. Nikeghbali A, Falavarjani KG, Kheirkhah A, et al. Pupil dilation 
with intracameral lidocaine during phacoemulsification. J Cata-
ract Refract Surg 2007;33:101–103.
42. Nikeghbali A, Falavarjani KG, Kheirkhah A. Pupil dilation with 
intracameral lidocaine during phacoemulsification: benefits for 
the patient and surgeon. Indian J Ophthalmol 2008;56:63–64.
43. Wilkie DA, Colitz CMH. Surgery of the canine lens. In: Gelatt 
KN, ed. Veterinary ophthalmology. 4th ed. Ames, Iowa: Blackwell 
Publishing, 2007;888–931.
44. Ahn JS, Jeong MB, Park YW, et al. A sub-Tenon’s capsule injec-
tion of lidocaine induces extraocular muscle akinesia and my-
driasis in dogs. Vet J 2013;196:103–108.
45. Mcgoldrick KE. Anesthesia and the eye. In: Barash PG, Cullen 
BF, Stoelting RK, eds. Clinical anesthesia. 2nd ed. Philadelphia: 
JB Lippincott, 1992;1095–1112.
46. Batista CM, Laus JL, Nunes N, et al. Evaluation of intraocular 
and partial CO
2
 pressure in dogs anesthetized with propofol. Vet 
Ophthalmol 2000;3:17–19.
47. Stephan DD, Vestre WA, Stiles J, et al. Changes in intraocular 
pressure and pupil size following intramuscular administration 
of hydromorphone hydrochloride and acepromazine in clini-
cally normal dogs. Vet Ophthalmol 2003;6:73–76.
48. Govêia CS, Magalhães E. Anestesia peribulbar com ropi-
vacaína – estudo da ação vasoconstritora. Rev Bras Anestesiol 
2010;60:495–512.
49. Serzedo PSM, Nociti JR, Zuccolotto EB, et al. Pressão intraocu-
lar durante bloqueio peribulbar com ropivacaína ou bupivacaí-
na: estudo comparativo. Rev Bras Anestesiol 2000;50:341–344.
50. Cangiani LM. Retrobulbar ou peribulbar: uma questão de no-
menclatura? Vet Bras Anestesiol 2005;5:261–262.
51. Slatter D. Sistema lacrimal. In: Fundamentos de oftalmologia veter-
inária. 3rd ed. São Paulo, Brazil: Editora Rocca, 2005;263–264.
52. Hodgson DS, Dunlop CI. General anesthesia for horses with spe-
cific problems. Vet Clin North Am Equine Pract 1990;6:625–650.
53. Yasui T, Karita K, Izumi H, et al. Correlation between vasodila-
tation and secretion in the lacrimal gland elicited by stimulation 
of the cornea and facial nerve root of the cat. Invest Ophthalmol 
Vis Sci 1997;38:2476–2482.
54. McLure HA, Rubin AP. Review of local anaesthetics agents. Mi-
nerva Anestesiol 2005;71:59–74.
55. Feitl ME. Anestesia Ocular. In: Krupin, T, Kolker, AE, eds. Atlas 
de complicações em cirurgias oculares. São Paulo: Editora Manole 
LTDA, 1997;1–15.57. 
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