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C L I N I C A L
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Visual and Anatomic Outcomes of Vitrectomy
With Temporary Keratoprosthesis or Endoscopy
in Ocular Trauma With Opaque Cornea
Dal W. Chun, MD; Marcus H. Colyer, MD; Keith J. Wroblewski, MD
! BACKGROUND AND OBJECTIVE: To examine the outcomes of vitrectomy in ocular trauma with
opaque cornea.
months. The number of eyes with retinal detachment
also improved from 10 (59%) at baseline to 3 (18%)
at 6 months.
! PATIENTS AND METHODS: This retrospective study included 17 eyes of 16 patients who underwent vitrectomy with temporary keratoprosthesis
or endoscopy at Walter Reed Army Medical Center,
Washington, DC, from March 2003 to October 2010.
! CONCLUSION: Vitrectomy may be safely performed in ocular trauma with opaque cornea using a
temporary keratoprosthesis or endoscopy with comparable outcomes. Endoscopy allows earlier diagnosis and
treatment of occult pathology and requires less time
and fewer procedures to implement than the temporary keratoprosthesis.
! RESULTS: A temporary keratoprosthesis was used
in 8 eyes (47%) and endoscopy in 9 eyes (53%). Overall, the number of eyes with visual acuity of 20/200
or better improved from 0 at baseline to 5 (29%) at 6
INTRODUCTION
Ocular trauma is often complicated by corneal
opacities that may interfere with the diagnosis and
management of posterior segment pathology. Faul-
[Ophthalmic Surg Lasers Imaging 2012;43:302310.]
born et al.1 reported that the cornea was involved
in 57% of severe perforating injuries in a civilian
population. The leading cause of blindness was
retinal detachment occurring either at the time of
injury or during the postoperative period. Among
From Walter Reed National Military Medical Center, Bethesda, Maryland.
Originally submitted April 13, 2012. Accepted for publication April 22, 2012.
Presented at the American Society of Retina Specialists Annual Meeting, August 24, 2011, Boston, Massachusetts.
The authors have no financial or proprietary interest in the materials presented herein.
The views expressed in the article are those of the authors and do not reflect the official policy of the Department of the Army, Department of Defense, or United
States Government.
Address correspondence to Dal W. Chun, MD, The Retina Group of Washington, 7501 Greenway Center Drive, Suite 300, Greenbelt, MD 20770. E-mail:
[email protected]
doi: 10.3928/15428877-20120618-09
302
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TABLE 1
Review of Vitrectomy With Temporary Keratoprosthesis for Ocular Trauma
No. of Eyes
Mean (Median)
Follow-Up (Mo)
Clear Graft at
Final Visit
Retina Attached at
Final Visit
Ahmadieh17
6
–
33%
67%
18
107
25
75%
88%
Gallemore
11
(9)
73%
91%
Garcia-Valenzuela19
22
–
59%
55%
Gelender20
7
(6)
43%
43%
Roters et al.
34
30
15%
88%
Yan22
7
28
43%
71%
Author
Dong
12
21
the injuries sustained in military combat treated at
Walter Reed Army Medical Center (WRAMC) from
February 2003 to November 2005, 46% of the 79
eyes with perforating injuries had entrance wounds
in the cornea.2 Most corneas retain adequate clarity to perform retinal surgery, but some have severe
opacities that preclude the diagnosis and repair of
posterior segment pathology. Corneal clarity may be
affected by severe stromal edema, sutures, glue, foreign bodies, and distortion caused by large oversewn
defects. Computed tomography and ultrasonography may yield clues to the presence of pathology
such as retinal detachment, intraocular foreign bodies (IOFBs), or occult rupture,3-7 but retinal tears
and detachments may still be missed. Early intervention may prevent some late complications, but an
alternative intraoperative viewing system may be desirable due to the increased risk of iatrogenic injury
in an eye with opaque cornea.8 Options include the
“open-sky” technique, temporary keratoprosthesis,
penetrating keratoplasty without temporary keratoprosthesis, or endoscopy.9-13
The use of temporary keratoprostheses for vitrectomy in ocular trauma was described by Landers et al.9
in 1981. These keratoprostheses were composed of a
polymethylmethacrylate cylinder with a threaded shaft
to secure it to the recipient cornea and a minus optic
to permit posterior segment surgery without the use of
additional lenses. The silicone temporary keratoprosthesis, described by Eckardt in 1987,14 is sutured to
host corneal tissue and allows improved access to the
periphery of the posterior segment due to its shorter
shaft length. In the same year that Landers et al. reported on their temporary keratoprostheses, a 1.7-mm
OPHTHALMIC SURGERY, LASERS & IMAGING · VOL. 43, NO. 4, 2012
small-diameter rigid endoscope was described for use
in vitrectomy.10 In 1990, Volkov et al.15 reported using
a flexible ophthalmic endoscope on 23 eyes for posterior segment surgery. Later that year, Eguchi et al.13
described using a 20-gauge video endoscope to view
the far periphery of the posterior segment and to examine the subretinal space in an eye with a proliferative
vitreoretinopathy (PVR) retinal detachment. In 1994,
the laser ophthalmic endoscope was reported for the
treatment of PVR.16 Several studies have examined
various temporary keratoprostheses for vitrectomy following ocular trauma (Table 1), but the ophthalmic
endoscope has not been widely adopted for this purpose despite its introduction more than 20 years ago.
The current study reports on the functional and anatomic outcomes of vitrectomy with either a temporary
keratoprosthesis or endoscopy in ocular trauma with
opaque cornea.
PATIENTS AND METHODS
This retrospective interventional case series was
conducted under a research protocol approved by the
Institutional Review Board of the WRAMC Department of Clinical Investigation by reviewing all of the
vitrectomies performed at WRAMC from March 2003
to October 2010. Inclusion criteria were age 18 years or
older, ocular trauma requiring vitrectomy, and opaque
cornea with no intraocular view. Exclusion criteria were
baseline “no light perception” (NLP) status, the use of
standard viewing techniques for any part of vitrectomy,
and incomplete data. Either a 7.0-mm Eckardt temporary keratoprosthesis (Dutch Ophthalmic USA, Exeter,
NH) or the Endo Optiks E2 Endoscopy System (Endo
303
Optiks, Little Silver, NJ) was used as the sole means of
intraocular visualization during vitrectomy in all of the
study eyes. All of the eyes in the keratoprosthesis group
were managed conservatively to allow for corneal clearing until an urgent indication for vitrectomy such as
retinal detachment was diagnosed ultrasonographically
or if vitrectomy was required for a less urgent condition
in the presence of a nonclearing cornea. The endoscopic procedures were performed when any indication for
vitrectomy was identified without waiting for corneal
clearing. All of the corneal procedures were performed
by one of two corneal surgeons and all of the retinal
procedures were performed by one of three retinal surgeons. The conventional viewing systems available at
WRAMC that failed to provide an intraocular view in
all of the study eyes included the Oculus BIOM 2 (Oculus, Inc., Lynnwood, WA) with disposable and autoclavable reduction lenses and the Volk Mini Quad XL
(Volk Optical, Inc., Mentor, OH) wide-angle indirect
contact lens viewing system.
Data Collection
Data obtained from transfer summaries, inpatient
and outpatient medical records, operative reports,
and slit-lamp photographs and surgical videos were
collected in a Microsoft Excel 2007 spreadsheet (Microsoft Corp., Redmond, WA). Ocular trauma data
included the mechanism and type of injury classified
according to the Ocular Trauma Classification.23,24 The
Ocular Trauma Score was also calculated for each eye.25
Baseline data were collected from the last clinical examination before vitrectomy and from intraoperative
findings. Snellen best-corrected visual acuity (BCVA)
was converted to logarithm of the minimum angle of
resolution (LogMAR) visual acuity scores for statistical
analysis. Eyes for which Snellen visual acuity could not
be measured were assigned LogMAR scores according
to a scale adapted from Holladay in which “counting
fingers” = 2.0, “hand motions” = 3.0, and “light perception” = 4.0.26 No baseline NLP eyes were included
in the study, but NLP in the postoperative setting was
assigned a score of 5.0. Overall corneal opacification
was sufficient to preclude conventional intraocular visualization in all study eyes, but the causes of opacification in the central 4 mm of the cornea were examined to compare the degree of injury between the
two groups. Dense vitreous hemorrhage was defined as
vitreous hemorrhage obscuring the posterior pole. The
304
macula was considered to be involved if any part of the
macula was affected by a condition or procedure. PVR
was graded according to the updated Retina Society
classification.27
Statistical Analysis
The data collection spreadsheet was exported to
the IBM Statistical Package for the Social Sciences
version 18 (IBM Corp., Chicago, IL) for analysis.
Continuous variables were compared using the Wilcoxon rank sum test. The Fisher exact test was used
to compare categorical variables. All reported P values
are two sided.
RESULTS
Ocular Trauma Data and Baseline Characteristics
From March 2003 to October 2010, there were
679 cases of military and civilian ocular trauma treated
at WRAMC. A total of 194 eyes required vitreoretinal
surgery, of which 98.5% were due to combat injuries
from Operation Iraqi Freedom and Operation Enduring Freedom. Sixty-four (33.5%) of the 191 eyes injured during Operation Iraqi Freedom and Operation
Enduring Freedom also had some degree of corneal injury. Seventeen eyes of 16 patients met the criteria for
inclusion in this study. Eight eyes of eight patients underwent vitrectomy with a temporary keratoprosthesis
and nine eyes of eight patients underwent endoscopy.
All of the temporary keratoprosthesis procedures were
performed from March 2003 to June 2008 prior to the
acquisition of the endoscope. All of the endoscopic vitrectomies were performed from June 2008 to October
2010.
Fifteen patients were American soldiers who sustained military combat injuries. One soldier had bilateral posterior segment trauma with opaque cornea.
One patient was a civilian whose failed corneal graft
dehisced after blunt injury. There were no differences
with respect to the ocular trauma variables (Table 2).
The two groups were similar with respect to the major
baseline characteristics between the two study groups
(Table 3); however, more retinal detachments involved
the macula in the keratoprosthesis group than in the
endoscopy group (P = .015).
All of the retinal tears in both groups were subclinical and were diagnosed intraoperatively. Five of
the seven retinal detachments (71%) in the keratopros-
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TABLE 2
Patient Characteristics and Ocular Trauma Data
Characteristic
Overall (n =17)
Keratoprosthesis (n = 8)
Endoscopy (n = 9)
a
27 ± 10
25 ± 7
28 ± 13
8/9
5/3
3/6
16 (94%)
8 (100%)
8 (89%)
.58
1 (6%)
0 (0%)
1 (11%)
.99
1 (6%)
1 (13%)
0 (0%)
.47
IOFB
10 (59%)
5 (63%)
5 (56%)
.99
Perforating
2 (12%)
1 (13%)
1 (11%)
.99
4 (24%)
1 (13%)
3 (33%)
.58
Zone 1
9 (53%)
5 (63%)
4 (44%)
.64
Zone 2
3 (18%)
1 (13%)
2 (22%)
.99
Zone 3
5 (29%)
2 (25%)
3 (33%)
.99
6 (35%)
3 (38%)
3 (33%)
.99
Age (y)
Right/left eyes
P
Mechanism of injury
Combat
Non-combat
Type of injury
Penetrating
Rupture
b
Zone of injury
Laceration > 10 mm
Uveal prolapse
Ocular trauma scorec
12 (71%)
5 (63%)
7 (78%)
.62
70 (37–80)
65 (47–80)
70 (37–80)
.82
IOFB = intraocular foreign body.
a
Mean ± standard deviation.
b
Zone 1: cornea; Zone 2: sclera up to 5 mm posterior to limbus; Zone 3: posterior to Zone 2.
c
Median (range).
thesis group were diagnosed preoperatively using ultrasonography. The remaining two retinal detachments
(29%) were discovered intraoperatively; the indications
for vitrectomy in these eyes were traumatic cataract and
nonclearing vitreous hemorrhage in one eye and IOFB
in a second eye. One eye in the keratoprosthesis group
underwent vitrectomy for IOFB without retinal detachment. Only one of the three retinal detachments
(33%) in the endoscopy group was diagnosed preoperatively. The remaining two retinal detachments (66%)
were diagnosed intraoperatively during removal of
traumatic cataract and dense vitreous hemorrhage. The
indications for vitrectomy in the remaining eyes in the
endoscopy group were IOFB in two eyes and traumatic
cataract with IOFB or dense vitreous hemorrhage in
four eyes. Grade C PVR occurred at similar rates in
both groups but extended posterior to the equator in
all of the affected eyes in the keratoprosthesis group.
In the endoscopy group, grade C PVR was found only
anterior to the equator.
OPHTHALMIC SURGERY, LASERS & IMAGING · VOL. 43, NO. 4, 2012
Surgical Data
Both the median number of days from injury to
vitrectomy and the median surgical time were significantly shorter in the endoscopy group (Table 4).
There were no differences in the surgical procedures
performed between the two groups except for macular
membrane stripping (P = .029) and perfluoro-n-octane
use (P < .0005), which were more common in the keratoprosthesis group. All of the eyes in the keratoprosthesis group received a corneal allograft at the conclusion
of vitrectomy.
3- and 6-Month Postoperative Outcomes
The visual and anatomic outcomes were similar for
the two groups at 3 and 6 months (Tables 5 and 6,
respectively). Six of the 17 eyes (35%) had 20/200 or
better BCVA at 3 months. The two eyes in the keratoprosthesis group with this outcome had worse vision
at 6 months due to recurrent retinal detachment in
one eye and corneal graft failure in another. One eye
305
TABLE 3
Baseline Preoperative Characteristics
Characteristic
Overall (n =17)
Keratoprosthesis (n = 8)
Endoscopy (n = 9)
4.0 (2.0–4.0)
4.0 (2.0–4.0)
4.0 (2.0–4.0)
.57
0 (0%)
0 (0%)
0 (0%)
.99
3–4+ stromal edema
17 (100%)
8 (100%)
9 (100%)
.99
3–4+ blood staining
5 (29%)
2 (25%)
3 (33%)
.99
Haze or scarring
8 (47%)
3 (38%)
5 (56%)
.64
Foreign bodies
7 (41%)
1 (13%)
6 (67%)
.05
Total hyphema
3 (18%)
1 (13%)
2 (22%)
.99
Traumatic cataract
11 (65%)
5 (63%)
6 (67%)
.99
Traumatic aphakia
4 (24%)
2 (25%)
2 (22%)
.99
Dense vitreous hemorrhage
10 (59%)
4 (50%)
6 (67%)
.64
a
LogMAR
20/200 or better BCVA
P
Corneal opacitiesb
Vitreous foreign bodies
7 (41%)
2 (25%)
5 (56%)
.34
Retinal foreign body damage
6 (35%)
3 (38%)
3 (33%)
.99
Traumatic maculopathy
7 (41%)
4 (50%)
3 (33%)
.64
Traumatic optic neuropathy
4 (24%)
1 (13%)
3 (33%)
.58
Retinal tears
13 (76%)
7 (88%)
6 (67%)
.58
Retinal detachment
10 (59%)
7 (88%)
3 (33%)
.15
Involving macula
7 (41%)
6 (75%)
1 (11%)
.015
Grade C PVR
9 (53%)
5 (63%)
4 (44%)
.64
Suprachoroidal hemorrhage
5 (29%)
3 (38%)
2 (22%)
.62
LogMAR = logarithm of the minimum angle of resolution; BCVA = best-corrected visual acuity; PVR = proliferative vitreoretinopathy.
a
Median (range).
b
Central 4 mm.
in the keratoprosthesis group improved from 20/400
at 3 months to 20/60 at 6 months with the removal
of a dense lens capsular membrane. All of the eyes in
the endoscopy group with 20/200 or better BCVA at
3 months maintained this level of vision at 6 months.
The causes of visual acuity worse than 20/200 at 3
months in the keratoprosthesis group were failed graft
with recurrent retinal detachment in two eyes and unrelated to the cornea in four eyes (maculopathy, recurrent retinal detachment, or lens capsule opacity). In the
endoscopy group, visual acuity worse than 20/200 at 3
months was accounted for by corneal opacities alone in
one eye, corneal opacities with maculopathy, neuropathy, or retinal detachment in three eyes, and maculopathy alone in one eye. At 6 months, visual acuity worse
than 20/200 in the keratoprosthesis group was accounted for by corneal opacities alone in two eyes, corneal opacities with maculopathy, neuropathy, or retinal
306
detachment in three eyes, and unrelated to the cornea
in two eyes (maculopathy or retinal detachment). In
the endoscopy group, this level of vision was accounted
for by corneal opacities in one eye and corneal opacities
with maculopathy or neuropathy in four eyes.
Only one repeat penetrating keratoplasty was performed during the study period and this occurred before
the 3-month visit. A total of four eyes underwent repeat
retinal detachment repair. In the keratoprosthesis group,
this was performed after the 3-month visit in one eye and
shortly after the 6-month visit in another eye. Two eyes
with recurrent retinal detachment in the keratoprosthesis group were not repaired due to poor visual prognosis
(NLP and bare light perception). In the endoscopy group,
repeat retinal detachment repairs were performed before
the 3-month visit in one eye and before the 6-month visit
in another eye. No surgical complications occurred in any
of the eyes during the study period.
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TABLE 4
Surgical Data
Characteristic
Overall (n =17)
a
Days from injury
Keratoprosthesis (n = 8)
Endoscopy (n = 9)
P
18 (7–96)
38 (11–87)
14 (7–96)
.034
Surgical time in hoursa
3.8 (1.8–10.5)
8.4 (5.8–10.5)
2.8 (1.8–3.8)
< .0005
Pars plana lensectomy
11 (65%)
5 (63%)
6 (67%)
.99
Membrane stripping
9 (53%)
4 (50%)
5 (56%)
.99
4 (24%)
4 (50%)
0 (0%)
.029
IOFB removal
Involving macula
10 (59%)
3 (38%)
7 (78%)
.15
Relaxing retinectomy
4 (24%)
2 (25%)
2 (22%)
.99
Perfluoro-n-octane
9 (53%)
8 (100%)
1 (11%)
< .0005
Laser or cryoretinopexy
15 (88%)
7 (88%)
8 (89%)
.99
Endotamponade
15 (88%)
8 (100%)
7 (78%)
.47
Air
2 (12%)
1 (13%)
1 (11%)
.99
SF6
2 (12%)
0 (0%)
2 (22%)
.47
C3F8
8 (47%)
6 (75%)
2 (22%)
.057
Silicone oil
3 (18%)
1 (13%)
2 (22%)
.99
5 (29%)
3 (38%)
2 (22%)
.62
Encircling buckle
IOFB = intraocular foreign body; SF6 = sulfur hexafluoride; C3F8 = perfluoropropane.
a
Median (range).
TABLE 5
3–Month Postoperative Outcomes
Variable
Overall (n =17)
Keratoprosthesis (n = 8)
Endoscopy (n = 9)
P
3.0 (0.2–4.0)
3.0 (1.0–4.0)
2.0 (0.20–4.0)
.34
6 (35%)
2 (25%)
4 (44%)
.62
Corneal graft failure
–
2 (25%)
–
–
Retinal detachment
5 (29%)
4 (50%)
1 (11%)
.13
Involving macula
4 (24%)
3 (38%)
1 (11%)
.29
a
LogMAR
20/200 or better BCVA
LogMAR = logarithm of the minimum angle of resolution; BCVA = best-corrected visual acuity.
a
Median (range).
TABLE 6
6-Month Postoperative Outcomes
Variable
Overall (n =17)
Keratoprosthesis (n = 8)
Endoscopy (n = 9)
P
2.0 (0.2–5.0)
3.0 (1.0–5.0)
1.3 (0.20–3.0)
.093
5 (29%)
1 (13%)
4 (44%)
.29
Corneal graft failure
–
3 (38%)
–
–
Retinal detachment
3 (18%)
3 (38%)
0 (0%)
.082
Involving macula
3 (18%)
3 (38%)
0 (0%)
.082
a
LogMAR
20/200 or better BCVA
LogMAR = logarithm of the minimum angle of resolution; BCVA = best-corrected visual acuity.
a
Median (range).
OPHTHALMIC SURGERY, LASERS & IMAGING · VOL. 43, NO. 4, 2012
307
DISCUSSION
The results of this study suggest that vitrectomy
may be safely performed with either a temporary keratoprosthesis or endoscopy in eyes with opaque cornea
following ocular trauma with comparable visual and
anatomic outcomes. Both techniques can be used to
view intraocular contents while maintaining a closed
system, which should reduce the risks associated with
“open sky” vitrectomy including intraocular hemorrhage, prolapse of intraocular tissues, and difficulty of
globe manipulation.9,11,28 The major differences observed between the two techniques are that endoscopy
allows earlier intervention and shorter surgical times
than does the temporary keratoprosthesis.
Earlier vitrectomy in the endoscopy group can
be attributed to differences in the management options available with each technique. Although the eyes
in each group sustained similar degrees of injury and
shared similar baseline characteristics, the decision to
perform vitrectomy in the endoscopy group was made
at the discretion of the surgeon when an indication
for vitrectomy was identified. The eyes in the keratoprosthesis group preceded the arrival of the endoscope
at WRAMC and were thus managed conservatively
with serial ultrasonography. The decision to perform
vitrectomy was made only after ultrasonographic evidence of a retinal detachment developed or if another
indication for vitrectomy was present in an eye with
a nonclearing cornea. Conservative management of
eyes without clinical evidence of a retinal detachment
is generally preferred over exploratory vitrectomy with
a keratoprosthesis because opaque corneas often gradually clear with time and the risk of corneal graft failure
is increased if penetrating keratoplasty is performed
during the first 2 months of ocular trauma.21 Severely
injured eyes are also more likely to require additional
procedures or silicone oil, which may stress the donor
endothelium and ultimately result in decompensation
or failure of the graft.21,29,30 In our study, corneal graft
failure was observed in two eyes (25%) at 3 months
and three eyes (38%) at 6 months. These eyes may have
been able to retain their native corneas if endoscopy
had been available at the time of their vitrectomy. If
their corneas failed to clear sufficiently with time, delayed allografting could have then been performed several months later when the eye was quiet and the risk
of graft failure was lower.
308
A major limitation of conservative management of
severe eye injuries is the difficulty of accurately diagnosing retinal tears and detachments ultrasonographically,
particularly in the presence of significant vitreous hemorrhage and organizing membranes. Latent retinal breaks
and detachments may be missed due to the presence of
media opacities and frequent anterior location of retinal
pathology.31,32 Many of the eyes in the endoscopy group
were found to have occult retinal tears and detachments
that would certainly have progressed to more extensive
pathology if the eyes had been managed conservatively.
Conversely, the pathology in the keratoprosthesis group
would have been less extensive if prompt vitrectomy
could have been performed before a retinal detachment
became evident ultrasonographically.
The benefit of early intervention is reflected in the
lower rates of macular involvement by retinal detachments and posterior grade C PVR in the endoscopy
group. Preretinal traction and PVR are the leading
cause of surgical failure in penetrating and perforating injuries and their early removal is known to reduce
late complications such as retinal tears and detachments.33-38 There is no consensus regarding the timing of vitrectomy following ocular trauma, but several
studies have reported better outcomes when surgery is
performed within the first 2 weeks.35,38-40 In our opinion, high-risk conditions predisposing to vitreoretinal
traction should undergo prompt vitrectomy even in the
absence of a frank retinal detachment. Conditions for
which early vitrectomy has been advocated include perforating injuries, lens disruption, ciliary body epithelial
damage, dense vitreous hemorrhage, significant vitreous loss, tractional complications, and endophthalmitis.1,28,41 IOFBs should also be removed promptly to
reduce the risk of retinal toxicity when their composition is unknown.36 Early IOFB removal also prevents
encapsulation, which may otherwise complicate their
safe removal.36,42
An indirect benefit of the early treatment of occult pathology and the prevention of its progression is
shorter surgical time. The management of more extensive retinal detachments and PVR in the keratoprosthesis group required additional procedures such as
macular membrane stripping and the instillation and
removal of perfluorocarbon liquids for intraoperative
tamponade and countertraction during membrane dissection. The shorter surgical times in the endoscopy
group are also directly related to differences in the pro-
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cedures required to implement each viewing system.
Whereas endoscopy was performed through standard
20-gauge sclerotomies and required no additional time
or invasive procedures to implement, the temporary
keratoprosthesis required additional time to remove
glue, revise sutures, trephinate the cornea, suture and
remove the keratoprosthesis, and graft corneal tissue at
the conclusion of vitrectomy. Although such data were
not available for this study, additional time may have
been incurred waiting for the corneal and retinal surgeons to prepare for their respective procedures. Prolonged surgery and additional invasive procedures may
be associated with higher operating costs and increased
risk of surgical and anesthetic complications.
The ease of creating surgical access for endoscopy
and its ability to be employed shortly after ocular trauma also allows it to be used for diagnostic purposes in
cases where the viability of the retina or optic nerve
are uncertain. With endoscopy, these structures may
be examined directly and help guide decisions for additional intervention.10 Direct examination of anterior
structures also allows the treatment of far peripheral
pathology such as cyclitic membranes and anterior
loop traction without requiring scleral depression or
globe manipulation.13,43 This is particularly helpful in
severe ocular trauma where closed but friable wounds
and suprachoroidal hemorrhage may be exacerbated
by excessive globe manipulation. The smaller incisions
required for endoscopy should also further reduce the
risk of hemorrhagic complications and prolapse of intraocular contents compared to those of the temporary
keratoprosthesis.
The limitations of endoscopy are related to its inferior image quality, changing intraocular perspective,
and steep initial learning curve. Video images obtained
through small-gauge endoscopy probes are inherently
of low resolution. The absence of stereopsis and the
dynamic intraocular perspective and field of view may
be disorienting, particularly in an eye with dense vitreous hemorrhage or disorganized intraocular contents.
Complex bimanual surgery, which may be required in
cases of extensive PVR, is also difficult to perform with
endoscopy. Other factors include the cost of the endoscopy system and its probes, which have a limited
lifespan.
In summary, vitrectomy may be performed safely
in eyes with opaque cornea following ocular trauma either with a temporary keratoprosthesis or endoscopy
OPHTHALMIC SURGERY, LASERS & IMAGING · VOL. 43, NO. 4, 2012
with similar visual and anatomic outcomes. Endoscopic vitrectomy requires less surgical time to use and facilitates the early diagnosis and treatment of occult retinal
tears and detachments. For these reasons, endoscopy
should be considered for use in most cases of ocular
trauma with opaque cornea and the temporary keratoprosthesis should be reserved for use in cases requiring
extensive bimanual surgery or for delayed vitrectomy
when the risk of graft failure is lower in eyes at low
risk of harboring occult retinal tears or detachments.
The limitations of this study are its small sample size,
its retrospective nature, and the difficulty of controlling for the complexities of ocular trauma. Additional
investigation comparing both techniques is required to
validate the findings of this study. A randomized, prospective, multicenter trial comparing the two viewing
systems may provide additional insight into the relative strengths and weaknesses of each and whether the
findings of this study can also be generalized to nontraumatic cases.
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