





























OPEN-GLOBE EYE INJURIES AND CHOICE OF 
MUSCLE RELAXANT: A REVIEW OF THE EVIDENCE

Authors

Joelle Benoit, BSN, RRNA 
Harris College of Nursing and Health Sciences, 
Texas Christian University, Fort Worth, Texas. 
Correspondence: j.benoit@tcu.edu  
 
Mark Welliver, CRNA, ARNP, DNP  
Associate Professor of Professional Practice 
School of Nurse Anesthesia 
Harris College of Nursing and Health Sciences, 
Texas Christian University, Fort Worth, Texas. 
Correspondence: m.welliver@tcu.edu 

Acknowledgements 
This review was conducted in partial fulfillment of the require-

ments for the Doctor of Nursing Practice School of Nurse 
Anesthesia at Texas Christian University. I want to acknowledge 
Mark Welliver, CRNA, ARNP, DNP, Faculty of TCU School 
of Nurse Anesthesia for expert advice and guidance in this 
assignment.

AbstrAct

A goal of treatment of open-globe eye injuries is preventing 
rises in intraocular pressure and the resulting loss of vitreous 
humor fluid from the eye globe. Surgical repair of these inju-
ries often requires general anesthesia and tracheal intubation. 
Normal intraocular pressure is 10-22 mm Hg, with varia-
tions between daytime and nighttime values. Factors such as 
eye muscle structure, fluid volume in the eye, overall hemody-
namic status, blood acidity, and mechanical pressure collectively 
contribute to fluid pressure within the eye. One factor that has 
been shown to be strongly correlated with increased intraocular 

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pressure is elevated venous pressure with physiological conditions 
during tracheal intubation (eg, straining, coughing, bucking). To 
determine intubation best practices, we reviewed the literature on 
succinylcholine, a depolarizing neuromuscular blocking agent, 
and nondepolarizing neuromuscular blocking agents. Research 
and case reports have not shown an association between the loss 
of ocular contents and succinylcholine administration. However, 
succinylcholine has been associated with increased intraocular 
pressure after administration and intubation. Nondepolarizing 
neuromuscular blocking agents, particularly rocuronium, admin-
istered before or instead of succinylcholine, have been found 
to attenuate the rise in intraocular pressure after induction and 
intubation.

keywords

Succinylcholine, nondepolarizing neuromuscular 
blocking agents, muscle relaxant, tracheal intubation, 
intraocular pressure, open-globe injury.

IntroductIon

A goal of treatment of penetrating injuries is avoidance of intra-
ocular pressure (IOP) elevation to prevent loss of vitreous humor 
fluid from the eye globe.1 When penetrating open-globe injuries 
occur, surgical repair often necessitates general anesthesia and 
tracheal intubation. Normal IOP is maintained at 10-22 mm Hg, 
with variations in daytime and nighttime values. Multiple factors, 
including the structure of eye muscles, fluid volume in the eye, 
overall hemodynamic status, blood acidity, and mechanical pres-
sure, contribute to the amount of fluid pressure within the eye.2 

One particular factor that has shown a strong correlation with 
increased IOP is an elevation in venous pressure with physi-
ological conditions that occur during tracheal intubation (eg, 
straining, coughing, bucking).2 Patients presenting with ocular 
trauma involving an open-globe injury require exquisite care 
and attention from anesthesia personnel to minimize elevations 



in IOP above normal ranges and prevent the loss of vitreous 
humor and, potentially, loss of the contents of the eye. Questions 
concerning the use of succinylcholine, a depolarizing neuromus-
cular blocking agent (NMBA), for intubation require a review 
of the evidence to determine best practice for this patient popu-
lation. The availability of alternative nondepolarizing NMBAs 
(eg, rocuronium) for intubation has created an opportunity for 
improved practice.

hIstory

Succinylcholine is considered the gold standard of NMBAs 
when the need for rapid sequence intubation (RSI) is present. 
Succinylcholine allows for quick, optimal intubating conditions 
when patients present with a need for immediately securing the 
airway and emergent surgical interventions.3 Over time, succi-
nylcholine has continued to be associated with an increase in 
IOP. This association has been through anecdotal professional-
to-professional reports and, recently, a single non-confirmatory 
case study that discusses the loss of vitreous humor after its 
administration presumably due to brief muscle fasciculations.3,4,5 
Libonati’s6 retrospective study of 250 patients having undergone 
ocular surgery found that succinylcholine did not cause loss of 
vitreous humor in any of their patients. 

Having been cited 107 times in scholarly literature reflects 
growing questioning of the belief against succinylcholine’s 
use in this patient population. Alternatively, nondepolarizing 
NMBAs at above normal doses, allow for comparable intu-
bating conditions to succinylcholine with the theoretical advan-
tage of reducing IOP due to their extraocular muscle relaxing 
effects with fasiculations.1 Anesthesia providers are faced with 
an evidence-based practice conundrum when determining which 
NMBA to administer for tracheal intubation in this particular 
patient population. Therefore, this evidence-based review sought 
to answer the question; in adult patients with open-globe ocular 
injuries does the administration of succinylcholine for intubation 

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compared to nondepolarizing NMBAs cause increases in IOP and 
support the theoretical risk of extrusion of aqueous humor?

lIterAture revIew

An initial, in-depth literature search was conducted without 
limit to date, utilizing PubMed, Embase, Clinical Key, ProQuest 
Nursing and Allied Health Source, and Web of Knowledge 
databases to locate scholarly literature comparing the admin-
istration of nondepolarizing NMBAs with succinylcholine in 
patients undergoing surgical repair for an open-globe injury. 
The key terms used included “succinylcholine,” “suxametho-
nium,” “open-globe injury,” “eye injury,” “intraocular pressure,” 
“neuromuscular blocking agents,” and “aqueous humor.” The 
results from the search did not meet the inclusion criteria, specifi-
cally the disclosure of loss of aqueous humor. 

Therefore, a second literature search was conducted with a 
broader approach. A combination of key terms was utilized for 
each database with the use of AND. The PubMed search was 
performed with a combination of “open-globe” AND “succinyl-
choline” AND “intubation” and generated 16 results. Embase 
was searched with a combination of “succinylcholine,” “ocular 
aqueous humor” AND “IOP,” based off of predicted search 
terms and resulted in 12 scholarly articles for review. A Web 
of Science topic search was conducted with the combination of 
“open-globe” and “succinylcholine” that produced 15 articles. 
The ProQuest database generated predicted search terms, and 
“eye injur*” AND “succinylcholine” were combined to deliver 
9 relevant articles. Clinical Key was searched with the combined 
key terms “eye injuries and succinylcholine” and refined to anes-
thesia specialty, and the database produced 29 results. Limiters 
were applied to each database to include only English-language 
articles and adult populations (18+ years of age). A cumulative 
total of 85 articles resulted. After the application of inclusion 
criteria specific to adult patients undergoing surgical procedures 
requiring intubation with intraocular pressure monitoring, the 



administration of nondepolarizing NMBAs and/or the admin-
istration of succinylcholine, a total of 7 articles were found 
relevant to the purpose of this review. In an attempt to locate 
additional studies, a Google Scholar search was conducted which 
produced similar findings.

The case study by Amadasun and Isesele4 describes a 34-year-
old trauma patient admitted to an emergency department with 
intra-abdominal injuries, limb injuries, and a laceration of the 
right cornea. The patient required emergency surgical interven-
tion of the abdominal injuries, and the injured eye was dressed 
with gauze and strapped prior to entering the operating room. 
Once induction agents were administered, cricoid pressure was 
applied and 100 mg succinylcholine was administered. 

An elevation in blood pressure was noted following intubation, 
and the patient required additional anesthetic agents post intu-
bation upon the return of spontaneous breathing.4 Direct visu-
alization of the injured eye was not performed after the dressing 
application until the completion of the abdominal surgical 
procedure, and there is no mention of the elapsed time between 
interventions.4 After laparotomy, the ophthalmologists reported 
for the corneal repair, only to find the vitreous humor had been 
extruded.4 Mechanical external pressure application to the 
injured eye such as touching the eye or the structures around the 
eye, elevation in blood pressure, and tracheal irritation (in this 
case, external cricoid pressure and intubation) have been shown 
to significantly elevate IOP, which could have led to the loss of 
intraocular contents with an open open-globe injury.2 

A major weakness of this case report is the lack of visual obser-
vation of the actual extrusion to identify a cause and effect. 
Other weaknesses include the application of mechanical pressure, 
intubation procedures, an abdominal surgical procedure with 
undisclosed measurement of continual neuromuscular moni-
toring, and a lengthy period with multiple opportunities for other 

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contributing factors to the vitreous humor extrusion. Therefore, 
succinylcholine administration cannot be definitively identified as 
the cause for the loss of ocular contents in this patient.

Lavery et al7 conducted a randomized controlled study that 
compared IOP readings in 30 patients following the administra-
tion of atracurium, a nondepolarizing NMBA, or succinylcho-
line. Ten of the 30 patients were administered induction agents 
that excluded muscle relaxants followed by laryngoscopy and 
tracheal intubation. Once a steady state of anesthesia and hemo-
dynamics was achieved, either 0.5 mg/kg of atracurium or 1.0 
mg/kg of succinylcholine was administered. IOP readings were 
obtained at 1-minute intervals for 5 minutes and once more at 10 
minutes post intervention. The intervention strategy allowed for 
the comparison of the two agents under conditions unaffected by 
extraneous factors such as tracheal irritation or hemodynamic 
instability. The findings of the steady state groups indicated that 
succinylcholine administration was responsible for a significant 
(P<0.025) elevation in IOP regardless of tracheal manipulation. 
The remaining 20 patients were administered either a combi-
nation of atracurium 0.75 mg/kg and thiopentone 5 mg/kg or 
succinylcholine 1.0 mg/kg and thiopentone 5 mg/kg prior to 
tracheal intubation, which was performed with cricoid pressure 
application. 

IOP readings were then obtained over 1-minute intervals for 
5 minutes post intubation. Thiopentone produced a significant 
(P<0.025) decrease in IOP post induction; however both groups 
displayed a significant (P<0.005) elevation in IOP immediately 
following tracheal intubation. In the atracurium group, IOP read-
ings did not breech baseline values. Immediately following intu-
bation, the succinylcholine group displayed a significant (P<0.05) 
increase in IOP readings that remained above baseline readings 
for 2 minutes. The results from the steady-state groups and the 
thiopentone groups support the practice of avoiding succinylcho-
line with open-globe injuries.



Vinick8 performed rapid sequence induction with tracheal intu-
bation on 45 patients between the ages of 18 and 65 years old. 
Three groups of 15 subjects were administered pre-inductions 
agents and then randomized to receive atracurium 0.5 mg/kg, 
rocuronium 0.6 mg/kg (a nondepolarizing NMBA), or succi-
nylcholine 1.0 to 1.5 mg/kg for neuromuscular blockade prior 
to tracheal intubation. Intubation was attempted at 60 seconds 
after NMBA administration. IOP readings were obtained prior to 
induction, after the administration of an NMBA, and then again 
1-2 minutes after intubation. Between-group comparisons were 
made using a two-tailed t-test, and a statistical significance was 
declared at a p-value of less than or equal to 0.05.8 Compared 
with the succinylcholine group, the rocuronium group displayed 
a significant (P=0.046) decrease in IOP from baseline post-induc-
tion, prior to intubation. The atracurium group displayed lower 
IOP values post-induction; however they were not considered 
significant (P=0.667). An increase in post-intubation values was 
noted in all groups without exceeding baseline or reaching statis-
tical significance. Rocuronium displayed greater control of IOP 
pre-intubation, indicating it is a viable alternative to succinyl-
choline administration in patients requiring intraocular surgeries 
with general anesthesia. 

Smith and Leano9 compared IOP after induction and tracheal 
intubation after administration of either pancuronium 0.1 mg/
kg (n=8, test group) or d-tubocurarine 3 mg (a nondepolar-
izing NMBA) before administration of succinylcholine 1.5 mg/
kg (n=6, control). In the test group, IOP readings were obtained 
after the loss of eyelid reflex, 2 minutes after pancuronium 
administration, and then for 1-minute intervals for 10 minutes. 
In the control group, IOP readings were obtained after the loss 
of eyelid reflex, 1 minute after the administration of succinylcho-
line (3 minutes after the administration of d-tubocurarine), and 
then again for 1-minute intervals for 10 minutes. The test group 
displayed a significant (P<0.01) decrease in IOP from induc-
tion to 3 minutes post intubation.9 There was an increase in IOP 

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from induction to 1 minute post intubation in the control group, 
however it was not determined to be statistically significant. 
The results from Smith and Leano9 conclude that pancuronium 
lowers IOP compared to succinylcholine that is pre-treated with 
d-tubocurarine.

A comparison study of 30 patients undergoing surgical proce-
dures, including intraocular procedures, was conducted by 
Konchigeri et al10 to determine if pretreatment with pancuronium 
would attenuate an increase in IOP following succinylcholine 
administration and tracheal intubation. Prior to induction of 
anesthesia, the control group (n=15) received saline pretreat-
ment, and the study group (n=15) received pancuronium 1.0 
mg. A Schiotz tonometer measured IOP levels at baseline before 
the administration of succinylcholine 1.0 mg/kg, then 1 minute 
after the administration of succinylcholine for neuromuscular 
blockade, and finally, 1 minute after intubation. Student’s t-test 
was applied, and P<0.05 was determined to be significant.10 The 
control group displayed elevations in IOP above baseline values 
after succinylcholine administration and intubation, while the 
test group displayed elevations after intubation only. This study 
revealed that pretreatment with a nondepolarizing NMBA is 
useful to attenuate IOP increases post succinylcholine administra-
tion. The nondepolarizing agent will not, however, mitigate an 
increase in IOP following direct laryngoscopy. 

Mitra et al11 performed a randomized, double-blind control 
study comparing IOP values in 40 patients receiving rapid-
sequence intubation without cricoid pressure. This study sought 
to contrast the effect of rocuronium 0.6 mg/kg (a nondepolar-
izing NMBA) with that of succinylcholine 1.5 mg/kg administra-
tion for neuromuscular blockade with tracheal intubation. IOP 
levels were obtained with Schiotz tonometry at baseline, after 
induction, 1 minute after administration of the NMBA, 1 minute 
after intubation, and then in 1-minute intervals for 3 minutes. 
Student’s t-test with Bonferroni correction was used to compare 



IOP values, and P<0.05 was considered significant. In the succi-
nylcholine group (n=20), IOP values were significantly elevated 
above baseline (P<0.01) after intubation. IOP values in the 
rocuronium group (n=20) did not rise above baseline values and 
remained significantly below baseline values for 5 minutes after 
induction (P<0.01). Mitra et al determined that rocuronium is 
a good alternative to succinylcholine administration to prevent 
unwanted elevations in IOP.

A randomized, double-blind study conducted by Chiu et al12 
compared IOP changes with the administration of rocuronium 
0.9 mg/kg or succinylcholine 1.5 mg/kg during RSI and tracheal 
intubation. IOP values were recorded prior to induction, prior to 
intubation, immediately after intubation, and again for 5 minutes 
after intubation with a Keeler Pulsair tonometer. Statistical 
analysis to compare IOP values was performed with a “paired 
t-test and two-way analysis of variance for repeated measure-
ments…”12 and a “…probability of less than 0.05 was the crite-
rion for statistical significance.”12 The succinylcholine group 
(n=15) revealed a significant increase in IOP post induction and 
intubation (P=0.01). The rocuronium group (n=15) displayed 
a reduction in IOP post induction (P=0.01) with an increase in 
values post intubation; however they did not exceed baseline 
values. Based on these findings, succinylcholine precipitates an 
elevation in IOP that is not seen with rocuronium administration.

dIscussIon

Considering the aforementioned weaknesses of the sole case 
report and that case reports are weak evidence in general, we 
focus on discussion of the research studies. Most hierarchies of 
evidence consider randomized controlled trials and meta-analysis 
of randomized controlled trials as the strongest evidence. Six 
studies were compared with a total of 189 subjects undergoing 
various surgical procedures requiring tracheal intubation that 
allowed for IOP monitoring. The sample sizes ranged from 14-45 
patients, with an age range of 17-70 years. 

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Nondepolarizing NMBAs were administered to 103 subjects, 
of whom 50 subjects received rocuronium prior to intubation, 
25 subjects received atracurium prior to intubation, 5 subjects 
received atracurium after intubation, and 23 patients received 
pancuronium. Succinylcholine was administered to 86 subjects. 
In 5 of the 6 studies,8-12 a comparison was made between succi-
nylcholine and a nondepolarizing NMBA. Sedation and induction 
was achieved by administering either a sedative-hypnotic agent or 
an opioid agent, or a combination of the two. IOP measurements 
were obtained at different times among the studies but in general 
consisted of post-induction (before intubation) and post-intuba-
tion time periods.

The nondepolarizing NMBAs displayed a slight consistent supe-
riority to succinylcholine with regards to reducing IOP prior to 
intubation in three studies,7-12 Although those particular agents 
were not able to consistently prevent an increase in IOP following 
intubation, they were able to maintain IOP levels below baseline 
readings or values obtained with succinylcholine. Rocuronium 
did attenuate an increase in IOP following intubation in two 
studies.11,12 Succinylcholine is not as efficacious as the nondepo-
larizing NMBAs at preventing elevations in IOP following induc-
tion or intubation. Following the administration of succinyl-
choline and tracheal intubation, IOP readings exceeded baseline 
readings, and some elevations remained for up to 3 minutes. 

The findings of this review offer guidance when considering 
choice of NMBA for intubation. Although succinylcholine has 
not been found to definitively cause extrusion of vitreous humor, 
it remains a theoretical concern as elevations in IOP occur with 
its administration. Rocuronium is a better choice especially for 
rapid-sequence induction. The research clearly indicates that 
rocuronium is the sole paralytic agent that will consistently main-
tain IOP readings at or below baseline levels after induction and 
tracheal intubation. Succinylcholine administration provides 
for efficient intubation conditions but without consistently 



maintaining IOP readings at or below baseline readings following 
induction or intubation. 

Atracurium and pancuronium allow IOP maintenance after 
induction and intubation; however, they may not provide 
successful intubating conditions, especially for rapid-sequence 
intubation, making them less desirable for these patients. 
Rocuronium, at doses of 1-1.5 mg/kg, provides adequate intu-
bating conditions comparable to succinylcholine for rapid-
sequence intubation. Tracheal intubation has been found to be 
the single most important contributing factor to an IOP eleva-
tion. Therefore, we should focus on the risk of vitreous humor 
extrusion during intubation. Fast, efficient, and minimally stimu-
lating intubation is prudent in this patient population. Further 
research should be conducted to identify any improved intu-
bating modalities (eg, video laryngoscopy, fiberoptic light wand, 
high narcotic/remifentanyl induction, sympatolytics) and other 
methodologies that may lessen IOP increases.

conclusIon And summAry

Research and case reports have not been able to create a reli-
able association between the actual loss of ocular contents and 
succinylcholine administration. However, succinylcholine has 
been found to be associated with increased IOP after its adminis-
tration and after intubation. Nondepolarizing NMBAs, particu-
larly rocuronium, administered prior to, or in place of, succinyl-
choline have been found to lessen IOP elevation after induction 
and intubation. Therefore, the research question “in adult 
patients with open-globe ocular injuries, does the administration 
of succinylcholine for intubation compared to nondepolarizing 
NMBAs cause increases in IOP and support the theoretical risk 
of extrusion of aqueous humor,” has been answered affirma-
tively with the available evidence and considering the following 
caveats: 

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• Succinylcholine administration will raise IOP above baseline. 
• Nondepolarizing NMBAs do not significantly raise IOP.
• Administration of a nondepolarizing NMBA prior to succi-

nylcholine will attenuate the rise in IOP.
• Laryngoscopy itself is related to more significant increases in 

IOP than either depolarizing or nondepolarizing NMBAs.
• Clinical considerations and future research should focus on 

attenuating rises in IOP caused by laryngoscopy. 

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