Download Orbital Fat Decompression for Thyroid Eye Disease: Retrospective

Original Investigation
Orbital Fat Decompression for Thyroid Eye Disease:
Retrospective Case Review and Criteria for
Optimal Case Selection
Marta Calsina Prat, M.D.*†, Alexandra L. Braunstein, M.D.*, Lora R. Dagi Glass, M.D.*,
and Michael Kazim, M.D.*
*Department of Ophthalmology, Columbia University Medical Center, New York-Presbyterian Hospital, New York,
New York, U.S.A.; and †Oculoplastics and Orbital Surgery Service, Department of Ophthalmology, Hospital del
Mar-Esperanza, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain
Purpose: The purpose of this study is to identify the
subgroups of thyroid eye disease (TED) patients most likely to
benefit from orbital fat decompression.
Methods: This retrospective study reviews 217 orbits of 109
patients who underwent orbital fat decompression for proptosis
secondary to thyroid eye disease. Charts were reviewed for
demographic, radiographic, clinical, and surgical data. Three groups
of patients were defined for the purposes of statistical analysis:
those with proptosis secondary to expansion of the fat compartment
(group I), those with proptosis secondary to enlargement of the
extraocular muscles (group II), and those with proptosis secondary
to enlargement of both fat and muscle (group III).
Results: Groups I and II, and those patients with
greater preoperative proptosis and those with a history of
radiation therapy were most likely to benefit from orbital fat
decompression. However, even those in group III or with lesser
proptosis appreciated significant benefit.
Conclusions: While orbital fat decompression can and, at times,
should be combined with bone decompression to treat proptosis
resulting from thyroid eye disease, orbital fat decompression
alone is associated with lower rates of surgical morbidity, and is
especially effective for group I and II patients, those with greater
preoperative proptosis, and those with a history of radiation.
(Ophthal Plast Reconstr Surg 2015;31:215–218)
T
hyroid eye disease (TED) produces soft-tissue inflammation, expansion, and scarring. During the acute phase of the
disease, orbital fat, extraocular muscles, and the lacrimal gland
may become infiltrated with lymphocytes and glycosaminoglycans.1,2 Both the extraocular muscle and orbital fat compartment
expand to variable degrees.1,2 The acute phase of TED typically
resolves after a period of 6 months to 2 years, followed by the
stable phase of TED.2
Clinical signs of soft-tissue infiltration, fibrosis, and
fat proliferation include diplopia, eyelid retraction, proptosis, orbital pain, and optic neuropathy. Axial proptosis may
result in functional deficit due to corneal exposure, significant
Accepted for publication June 11, 2014.
Presented in part at the American Society of Ophthalmic Plastic and
Reconstructive Surgery 42nd Annual Fall Symposium in 2011 in Orlando, FL.
The authors have no financial or conflicts of interest to disclose.
Address correspondence and reprint requests to Michael Kazim, M.D., 635 W.
165th St, Room 207, New York, NY 10032. E-mail: [email protected]
DOI: 10.1097/IOP.0000000000000260
Ophthal Plast Reconstr Surg, Vol. 31, No. 3, 2015
disfigurement, and more rarely stretch optic neuropathy. The
goal of fat and bone decompressive surgery is to alleviate these
signs and symptoms.3–6
Decompression surgery produces its effects by normalizing the ratio of orbital bony volume to orbital soft-tissue volume. This has traditionally been achieved by removing one or
more of the orbital walls to enlarge the socket volume. Orbital
bone decompression was first reported in 1911; the procedure
has subsequently been modified but continues to be associated
with postoperative strabismus, sinusitis, infraorbital anesthesia,
globe ptosis, loss of vision, and cerebrospinal fluid leakage.1,7–10
To decrease the incidence of postoperative complications, orbital fat decompression was introduced in 1984.5,6 Its
conception was aided by the advent of modern orbital imaging
techniques. CT and MRI have elucidated the contribution of the
enlarged orbital fat compartment in TED.4,11 Image analysis and
patient selection coupled with a technique for surgically debulking the orbital fat compartments have provided a safe and effective additional method of orbital decompression.5 While recent
literature linearly correlates retrobulbar volume change on CT
with reduction in proptosis and the amount of fat removed in
decompression surgery,12 limited literature exists regarding the
best candidates for orbital fat decompression.
The purpose of this study is to identify the subgroups of
TED patients most likely to benefit from orbital fat decompression. The primary outcome was change in Hertel measurement
after fat decompression. This outcome was secondarily analyzed
with respect to smoking history, radiation history, fat removed
intraoperatively, and postoperative complications.
METHODS
This study was approved by the authors’ Institutional Review
Board. A retrospective review of 217 orbits of 109 patients who had undergone solely orbital fat decompression over a 19-year period (1990–
2010) by a physician (M.K.) was performed. Patients were offered this
surgery if they were determined to be in the stable phase of TED by
the senior investigator (based on clinical history, physical examination,
serology, and radiographic findings), and suffered from disfiguring proptosis, recalcitrant corneal exposure, or complaints of persistent deep
orbital pain. Patients were excluded if they had orbital fat decompression for compressive optic neuropathy or bony decompression prior to
or in conjunction with orbital fat decompression.
Charts were reviewed for demographic data and for the following clinical parameters: history of tobacco use, prior radiotherapy,
CT or MRI classification of extraocular muscle size, preoperative and
3-month postoperative Hertel exophthalmometry, formal orthoptics
measurements using cover–uncover testing and prism measurements in
215
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Ophthal Plast Reconstr Surg, Vol. 31, No. 3, 2015
M. C. Prat et al.
all 9 cardinal fields at near and at distance (performed for those patients
reporting preoperative diplopia in primary or reading positions), surgical techniques (superior and inferior, inferior, transcutaneous, or transconjunctival approach), quantity of fat removed per orbit ( ml) when
available, and surgical complications including loss of vision, optic neuropathy, hemorrhage, diplopia, infection, poor wound healing, and reactivation. Fat removed was measured via displacement of saline in a 3-ml
syringe. Three groups of patients were defined by qualitative analysis of
CT/MRI. Group I demonstrated proptosis due to expansion of the fat
compartment, with normal extraocular muscles (Fig. 1). Group II demonstrated exclusive enlargement of the extraocular muscles, defined as at
least 3-fold enlargement in at least 3 muscles (Fig. 2). Group III demonstrated enlargement of both muscle and fat compartments, with muscle
enlargement defined as at least 2-fold enlargement of at least 1 muscle
(Fig. 3). Statistical analysis was performed using bivariate Student t test,
one-way analysis of variance, bivariate χ2 test, and Pearson correlation.
Surgical Procedure. Orbital fat decompression was performed under
general anesthesia. Patients received preoperative intravenous antibiotics and corticosteroids, and postoperative intravenous antibiotics for 24
hours. Oral corticosteroids were continued for 5 to 7 days postoperatively to minimize swelling.
A lower eyelid transconjunctival approach was routinely taken,
though 7% had a transcutaneous approach. In the rare cases where the
FIG. 3. Group III. Enlargement of both muscle and fat
compartments.
lower eyelid was tightly opposed to the globe, a lateral canthotomy and
inferior cantholysis were performed to facilitate access to the inferior
fornix and the lateral orbital compartment. The conjunctiva and lower
eyelid retractors were incised approximately 5 mm below the inferior
boarder of the tarsal plate. The septum was opened with a unipolar
needle-tipped cautery, and the underlying fat pads were identified. The
intra- and extraconal fat was removed using malleable retractors to protect the lower eyelid and the globe. When hemostasis was assured, the
conjunctiva was closed with two absorbable sutures. If a canthotomy
and a cantholysis were performed, the canthal structures were repaired.
On occasion, a concurrent superior approach was felt to be appropriate
based on the presence of prolapsing orbital fat. In this approach, the superonasal fat pad was accessed through a eyelid crease incision limited
to the nasal and one-third of the eyelid.
To measure the volume of fat removed, the specimen was placed
in a 3-ml syringe partially filled with normal saline, and the volume of
fat excised was estimated by the displacement of the saline. The volume
of fat removed was routinely within 0.5 ml of symmetry bilaterally.
RESULTS
FIG.1. Group I. Proptosis due to expansion of the fat compartment, with normal extraocular muscles.
FIG. 2. Group II. Exclusive enlargement of the extraocular
muscles.
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A total of 217 orbits of 109 patients with TED who underwent
solely orbital fat decompression were reviewed.
One hundred eighty-four orbits (85%) were female and 33
(15%) were male. The average age was 44 years (range 15–73). Sixteen
orbits of 154 patients with documented smoking patterns had a history
of tobacco use (10%).
One hundred twenty-nine orbits (59%) were included in group I
(fat expansion), 12 orbits (6%) in group II (muscle expansion), and 76
patients (35%) in group III (fat and muscle expansion).
Fifty-one patients had preoperative diplopia and therefore underwent formal motility measurements prior to surgery (47%).
Eighty-one orbits (37%) underwent 2-compartment orbital fat
decompression (superior and inferior) and 136 (63%) underwent inferior orbital fat decompression alone.
Twenty-seven orbits (12%) received fractionated orbital radiotherapy to treat active TED prior to the stabilization of TED and ultimate
surgery; these patients were equally divided between groups I, II, and III.
When the results were analyzed based on the preoperative assessment of soft-tissue expansion, the largest proptosis reduction was
appreciated in group I (fat compartment expansion) and group III (both
muscle and fat expansion) patients (mean 3.27 mm and 3.47 mm proptosis reduction, respectively). Less proptosis reduction was achieved
in group II patients (enlargement of the extraocular muscles; mean
2.83 mm). See Table for preoperative and postoperative measurements
according to group. One-way analysis of variance testing found no statistically significant differences between groups regarding proptosis reduction in millimeters.
© 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.
Copyright © 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc. Unauthorized reproduction of this article is prohibited.
Ophthal Plast Reconstr Surg, Vol. 31, No. 3, 2015
Fat Decompression in Thyroid Eye Disease
Preoperative and postoperative Hertel
exophthalmometry
Group
Group I
Group II
Group III
Preoperative
Postoperative
Mean (SD)
23.5
23.1
23.9
20.3
20.2
20.4
3.3 (1.5)
2.8 (1.5)
3.5 (1.6)
Results are divided according to group.
SD, standard deviation.
Proptosis was reduced by an average of 3.1 mm in patients who
underwent inferior decompression alone. In comparison, proptosis was
reduced by an average of 3.63 mm in patients who underwent combined
superior and inferior decompression. This difference was statistically
significant (p < 0.001).
Positive Pearson correlation (r = 0.51, p < 0.001) was found between preoperative degree of proptosis and postoperative proptosis reduction (Fig. 4). It is notable that there was an approximately 1:1 ratio of
fat removal (mean 3.2 ml) to difference in pre- and postoperative Hertel
measurement (mean 3.3 mm) in the 35 patients in whom the amount of
fat removed was quantified (r = 0.42, p < 0.015).
A history of smoking did not affect the amount of proptosis reduction (p = 0.6). However, a history prior to radiation therapy did appear to be of import; those with no history of radiation had an average of
3.23 mm ± 1.54 mm reduction, whereas those with a history of radiation
had an average of 3.95 mm ± 0.78 mm reduction (p = 0.046).
None of the study patients suffered surgically induced optic neuropathy. An improvement in diplopia and motility was observed in 15
of 51 patients (29%) with formal pre- and postoperative orthoptics measurements. Ocular motility worsened temporarily in 2 of the 51 patients
(4%), but improved spontaneously to the preoperative level. There were
no cases of new onset diplopia, loss of vision, hemorrhage, optic neuropathy, reactivation, poor wound healing, or infection postoperatively.
DISCUSSION
After retrospectively examining the preoperative indications and postoperative outcomes of patients in practice undergoing orbital fat decompression technique, the authors found
that patients with fat or both fat and muscle expansion, as well
as greater amounts of proptosis, were more likely to enjoy
greater reduction in proptosis postoperatively, independent of
FIG. 4. Correlation between preoperative degree of proptosis
and postperative reduction in proptosis. Positive Pearson correlation was found.
their smoking history. However, even those with muscle expansion or smaller amounts of proptosis appreciated significant
benefit. A history of radiation therapy was not detrimental, and
was perhaps even of benefit.
Orbital fat decompression has traditionally been accomplished through a variety of surgical approaches; the 2 most
commonly employed are transconjunctival (with upper or lower
eyelid) or transcutaneous subciliary incisions. Inferiorly, the largest volume of orbital fat is removed from the nasal and temporal
quadrants, as removal of the central fat pad has minimal effect on
orbital volume, and aggressive resection in this zone can result in
a hollowed appearance of the eyelid with accentuation of residual
proptosis. Superiorly, the largest volume of orbital fat is removed
from the nasal quadrant, although this tends to be less effective
than inferonasal fat pad resection, and the authors reserve surgery in this quadrant to those patients with significant prolapsing
fat. While superolateral fat removal has been described,6 these
attempts risk damaging the lacrimal gland itself or its neurovascular supply. The authors therefore avoid the superotemporal
quadrant in their surgical technique, as do Adenis et al.13 In cases
in which there is an asymmetry of greater than 2 mm in preoperative Hertel measurements, the authors achieve additional decompression via bone thinning or removal in the more proptotic
orbit, rather than attempting an asymmetric fat decompression.
It is of note that while the definition of intra- and extraconal fat
would seem anatomically clear, in their experience, the separation between these 2 areas is blurred, with absolute knowledge
of intraconal fat removal defined by direct visualization of the
extraocular muscles. Given the redistribution of fat occurs both
intra- and postoperatively after decompression, the authors find
that the conceptual distinction between intra- and extraconal fat
removal may not be of practical significance.
This study has several limitations. Ideally, surgical success would be related to pre-TED Hertel measurements, rather
than preoperative Hertel measurements. Pre-TED Hertel measurements are not routinely available and in the authors’ practice
are only estimated by inspection of premorbid photographs. It
is possible that the degree of preoperative proptosis influenced
the surgeon’s choice as to how much fat was removed, such
that those with greater proptosis would have more fat removed.
However, the authors remove as much fat as considered safe in
all patients, rather than basing the amount of fat removed on the
amount of preoperative proptosis. Moreover, using this approach
they have not produced an overcorrection in any patient.
The authors did not anticipate the 29% objective improvement in preoperative diplopia as a result of the surgery. In their
practice, orthoptics measurements are only routinely obtained
in patients who complain of diplopia. As a consequence, orthoptics were recorded in 51 of 109 cases. Though limited by the
retrospective nature of this study and lack of quality of life
surveys postoperatively, this result suggests that the effect of
orbital fat decompression goes beyond reduction in proptosis.
The authors speculate that attendant to the mobilization and
removal of orbital fat is the lysis of pathologically fibrosed
intramuscular septations, described by Koornneef,14 which in
turn is responsible for improvement in ocular rotations. While
they did examine muscle balance by orthoptics measurement in
a subset of patients, it would be of interest to obtain the same
measurements in all cases and to more carefully assess the effect
of orbital fat decompression surgery on ocular rotations.
The authors did not quantify the volume of muscle enlargement or fat enlargement on preoperative imaging; rather they
used a qualitative assessment of fat expansion, muscle expansion,
or a combination thereof to guide the placement of patients into
group I, II, or III. In addition, because of the nature of largely
© 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.
217
Copyright © 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc. Unauthorized reproduction of this article is prohibited.
Ophthal Plast Reconstr Surg, Vol. 31, No. 3, 2015
M. C. Prat et al.
referral-based practice, imaging did not have consistent slice
thickness. This correlates with everyday practice. The authors
hope that this relatively efficient qualitative analysis will serve as
a general framework when examining TED patients.
Finally, this study is limited by the nature of the authors’
practice, a university-based tertiary referral that sees more severe
TED than average. It is of note that in the most severe cases, fat
decompression alone would not generally be considered.
In summary, while fat decompression can and, at times,
ought to be combined with bone decompression, fat decompression
in and of itself results in reliable proptosis reduction in the properly selected patients, reduced surgical morbidity, and occasionally
improvement in diplopia in patients with restrictive strabismus.
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© 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.
Copyright © 2014 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc. Unauthorized reproduction of this article is prohibited.