Keywords
orbit - skull base - neuro-ophthalmologist - optical coherence tomography - orbital
echography - orbital - surgery
Introduction
Each patient deserves our attention and our best risk–benefit analysis to assist them
in decision making—this is the process of informed consent. The clinical evaluation
is the first step of the process, during which the physician–patient relationship
begins, based on a foundation of knowledge, respect, and trust, and through which
optimal therapeutic plans may be constructed.
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“It takes a village” - include medical and surgical neuro-ophthalmology and/or oculoplastic
surgery in your multidisciplinary skull base team.
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Meet with your team to develop a standardised methodology of evaluation a standardized
methodology of evaluation.
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Valuable ancillary testing includes, but is not limited to, automated perimetry, optical
coherence tomography, fundus photography and orbital echography.
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In some cases, orbital fine needle aspiration biopsy (FNAB) may obviate the need for
open surgery, or may aid in surgical planning.
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Not every orbital disease calls for a surgical “solution”.
It Takes a Village
We often “share” patients with colleagues, depend on our colleagues' expertise, and,
at times, work together in multidisciplinary clinics and/or in the surgical theaters.
The initial evaluation of the “orbital patient” may be in an emergency department,
an urgent care facility, a primary care physician's office, or in the office of an
internal medicine subspecialist, a neurologist, an ophthalmologist, an otolaryngologist,
a plastic surgeon, or a neurosurgeon. Any patient with orbital disease requires a
complete evaluation by an orbital specialist, and the subsequent communication of
these findings to the referring physician and to the other members of the multidisciplinary
team.[1]
[2]
Chief Complaint
Orbital disease may first be evident to the patient, to others who may notice a change
in the patient's appearance, to a physician during examination for unrelated reasons,
or may be an “incidental finding” in an imaging study. The patient may complain of
a change in his or her appearance or discomfort. The patient may have had changes
in vision—“My vision is blurry … When I stand up, my vision blacks out for a second
or two … When I look to the side, my vision blacks out … My peripheral vision is bad
… I have double vision.” On occasion the chief complaint is, “I had a (CT/MRI) done
for (headache/injury/weakness/etc.) and they found a tumor behind my eye.”
History of Present Illness
History of Present Illness
Onset, progression, and variability are important in the history. It is sometimes
helpful to compare appearance with old photos. If prescription lenses have been in
use, the history of initiation of use and stability or instability of the power of
lenses needed may be helpful clues.
Medical History
Specifically, history of hypertension, diabetes, sinonasal disease, cranial or intracranial
disease, cancer, thyroid disorder, autoimmune disease, immunosuppression, injuries,
surgeries, complications of anesthesia or surgery, bleeding diatheses, tumors, and
vascular malformations will be instructive family history of genetic disorders, bleeding
disorders, tumors, and complications of anesthesia should be noted, and a proper social
history should also be taken.
Review of Records
Of course, personal review of records, reports, and “films” (today known as images)
by the orbital surgeon and/or neuro-ophthalmologist is invaluable.
Clinical Examination and Ancillary Tests
Clinical Examination and Ancillary Tests
The examination rightly begins with inspection of eyewear, with determination of prescriptive
power, including measurement of any prism correction within the spectacles, and/or
notation of fit of contact lenses, if in use. Sometimes refraction is required as
a diagnostic test.[3] Visual acuity, with best possible lens correction, should be measured at distance
in Snellen notation. Near vision may also be measured but is not a substitute for
determination of distance acuity. Establishment of “20/20 vision” does not indicate
the absence of optic nerve compromise by an orbital process.[4] Vision may also be assessed with aid of contrast sensitivity testing, color vision
testing, and perimetry (visual field analysis). Not every orbital patient requires
formal contrast sensitivity and color plate testing, but it is helpful to hold a red
target before the patient and to alternately occlude the eyes, inquiring if one eye
perceives the red to be more or brighter red, as red desaturation may be an early
sign of optic nerve compromise.
Perimetry should be done prior to instilling diagnostic eyedrops. Most often this
is accomplished via quantitative static perimetry, such as Humphrey 24-2 or 30-2,
but may be performed by other means, such as Goldmann perimetry, Octopus perimetry,
or others. One strives to utilize testing which is standardized and may be performed
in another part of the world on similar apparatus, allowing reliable comparisons of
test results.
Inspection of eyelids and orbits follows. Is there asymmetry, eyelid edema, erythema,
ecchymosis, tenderness? Is the eyelid contour normal? A lateral flared retraction
of the upper eyelid is suggestive of thyroid eye disease or TED,[5]
[6] while an “S-shaped ptosis,” with lateral depression of the upper eyelid, is suggestive
of a lacrimal gland mass or inflammatory process. The margin reflex distance (MRD)[7] of the upper (MRD-1) and lower (MRD-2) eyelids is measured and recorded ([Fig. 1]). An exophthalmometer is used to record the anterior projection of each globe in
reference to the lateral orbital rim, while also recording the base setting, so as
to use the same base setting at subsequent visits to allow accurate assessment of
change, if any. Globe displacement may also be horizontal or vertical and this relative
position of one globe to the other should also be assessed and recorded. Taking and
including photographs in the medical record is also useful.
Fig. 1 A millimetric rule may be used to measure the distance from the upper eyelid margin
to the light reflex (MRD-1) and from the lower eyelid margin to the light reflex (MRD-2),
which in this case will demonstrate a relative 0.5 mm ptosis or the right upper eyelid.
MRD, margin reflex distance.
Facial motor function is assessed and recorded. Unilateral orbicularis weakness may
present with a complaint of “bulging” of the eye, due to a “wide-eyed” appearance,
and/or a complaint or finding of “ptosis” on the opposite side. There may be attendant
complaints of eye pain, redness, or tearing. Patients with a remote history of “recovered”
facial palsy may have a combination of orbicularis weakness and spasm, sometimes accompanied
by orbicularis “tics” or fasciculations.
Comparative sensitivity to light touch in the distribution of the first, second, and
third branches of the trigeminal nerve is assessed and recorded. Pupils should be
assessed and measured. The diameter of each should be measured and recorded under
conditions of both dim and bright illumination, and if there is anisocoria in one
or both circumstances, the cause of the anisocoria[8] should be determined before the patient leaves the examination suite, as this may
be a sign of neurosurgical emergency in the case of an acute Horner's or third nerve
palsy. Of course, there are many nonurgent causes of anisocoria, including, but not
limited to, congenital anomaly, prior trauma or intraocular surgery, prior or active
iritis, pseudoexfoliation syndrome, diabetic iridoplegia, or Adie's pupil. The presence
or absence of a relative afferent pupil defect (RAPD) is critical in consideration
of unilateral or asymmetric optic neuropathy.
Sensorimotor examination[9] is vital in assessing and measuring eye movement abnormalities in patients with
orbital disorders. Even in patients with no complaint of diplopia, there are often
abnormalities. A simple screening tool is the “alternate cover test”: the patient
is instructed to fixate on a distant target, such as one letter in the eye chart,
and the eyes are alternately occluded, moving the cover from one eye to the other
([Fig. 2]). If there is an inherent “imbalance,” you may see a refixation movement as the
uncovered eye reacquires the target; in cases of small angle deviations, you may not
see a refixation movement, and it is helpful to ask the patient, “As I go from one
eye to the other, does the letter seem to move side-to-side or up or down?” If there
is misalignment,[10] it should be measured quantitatively by means of neutralization with a prism ([Fig. 3]). The assessment and measurement should be made in different fields of gaze. Following
these measurements, ductions (movement of each eye individually) should be evaluated,
noting, measuring, and recording the range of motion of each eye in all directions,
either by lateral and vertical version light reflex testing or qualitative (0–4 scale)
recording of under or overaction ([Fig. 4]). If there is a ductional deficit, it should be determined if this is on the basis
of weakness of an extraocular muscle, or a mechanical restriction of eye movement.
A forced duction test[11] may be helpful, in which a toothed forceps is utilized to grasp the topically anesthetized
globe while the patient attempts to look in the direction of deficit. If the examiner
is able to rotate the eye farther than the patient can, the deficit is attributed
to weakness rather than restriction. Determination of ductional deficits due to paresis
or restriction may alternatively be made by measurement of intraocular pressure (IOP)
in different gaze positions.[12] If the IOP remains stable in attempted gaze at the limit of the ductional deficit,
this is due to weakness. In the case of restriction, the effort of contraction of
the functional but restricted extraocular muscle leads to momentary compression of
the globe and elevated IOP. The sensorimotor testing is then completed with assessment
of the character of saccadic and smooth pursuit eye movements and notation of the
presence or absence of nystagmus.
Fig. 2 A cross cover test will reveal misalignment (tropia) or potential misalignment when
fusion is interrupted (phoria).
Fig. 3 Prism neutralization should be done to measure and record strabismic deviation in
all gaze positions. This is useful diagnostically as well as to assess change over
time.
Fig. 4 Ductions.
Slit lamp biomicroscopy is performed, with further assessment of the eyelid margins
and the conjunctiva[13] ([Figs. 5] and [6]). The cornea, anterior chamber, iris, pupil, and crystalline lens or intraocular
lens implant are inspected. The tear film and cornea are stained with fluorescein
and examined with a cobalt blue filter, allowing assessment of tear film adequacy
and tear flow; adherent staining of the cornea is indicative of corneal epithelial
disturbance. If there is blockage of egress of fluorescein, the lacrimal sac is compressed
to assess presence or absence of reflux to assess patency of the nasolacrimal drainage
system. IOP is then measured.
Fig. 5 An elderly woman presented with complaint of “pressure” behind her eyes, redness
of the eyes, and horizontal diplopia. Examination revealed bilateral sixth cranial
nerve weakness and arterialization of conjunctival veins, leading to suspicion of
unilateral or bilateral dural cavernous sinus fistula (or dural arteriovenous malformation).
Fig. 6 Vertically oriented B-mode echography of the left orbit revealed dilation of the
superior orbital vein, seen in cross section above the optic nerve and below the superior
rectus.
Dilating drops are instilled (providing the patient does not have narrow, occludable
angles) and ophthalmoscopy is performed with assessment of the vitreous, retina, and
optic nerve head. Mid-orbital tumors may be accompanied by optic nerve swelling, whereas
small orbital apex tumors may cause progressive optic atrophy in the absence of swelling.[14] A cilioretinal shunt vessel may be indicative of optic nerve sheath infiltration
([Fig. 7]).[15]
[16] The appearance of the optic nerve and retina may be documented by fundus photography.
Fig. 7 Fundus photos demonstrate normal appearance of the left optic nerve head, but right
optic atrophy and a prominent cilioretinal shunt vessel in this patient with a history
of progressive loss of vision of the right eye found to be secondary to optic nerve
sheath meningioma (This image is provided courtesy of Steven A. Newman, MD).
Optical coherence tomography (OCT) is an extremely helpful ancillary test. OCT is
customarily performed for quantitative measurement of retinal nerve fiber layer (RNFL)
thickness ([Fig. 8]), retinal ganglion cell (RGC) layer thickness ([Fig. 9]), and qualitative and quantitative assessment of macular health. In the presence
of optic nerve damage, the RNFL and RGC layers will be thinned and the quantitative
measurement is a reliable indicator of stability or progression of damage over time.
In the presence of orbital disease, RGC layer thickness is a more reliable indicator
than RNFL thickness because the RNFL thickness may be increased by venous congestion.
So, as a consequence, one may view increasing RNFL thickness over time as an objective
measurement of increasing venous congestion, and/or an indication of optic nerve head
inflammation, infiltration, or ischemia. The OCT is more sensitive in the assessment
of change over time than is ophthalmoscopy, serial fundus photography, or magnetic
resonance imaging (MRI). A change of +/− 4 microns in average or regional RNFL or
RGC layer regional thickness is often clinically significant, as compared with changes
of +/− 500 microns for 3T MRI or +/− 100 microns for 7T MRI.
Fig. 8 Optical coherence tomography of normal optic nerve heads (ONH) and retinal nerve
fiber layer (RNFL)—the cross-sectional thickness of the RNFL is measured in microns,
360 degrees around each optic nerve head.
Fig. 9 Optical coherence tomography of normal maculae, with measurement of the retinal ganglion
cell layer thickness in microns.
Ophthalmic echography, performed by a skilled echographer, may also be a useful adjunctive
test. It is more sensitive than computed tomography (CT) or MRI in the assessment
of intraocular, retinal, or subretinal disease processes, and is additive to CT or
MRI of the orbit in characterization of orbital disease. If CT or MRI has been used
in the initial evaluation of an orbital abscess or mid- or anterior orbital inflammatory
disease, such as posterior scleritis, serial B-mode echography is adequate in assuring
response to treatment, thus minimizing the need for serial CT or MRI.[17] If CT or MRI has identified a mid- or anterior orbital tumor or infiltrative process,
adjunctive echography is helpful in assessment of the internal acoustic characteristics
of the lesion, in that lymphoma, melanoma, and cysts have no or low internal reflectivity,
and other processes have mid- (such as schwannoma) to high internal reflectivity (such
as many carcinomas or cavernous hemangioma).[18] Echography also allows for real-time dynamic assessment of adherence or infiltration
of tumorous processes to adjacent tissues. B-mode echography is also a useful tool
for image-guided fine needle aspiration biopsy (FNAB) of mid-orbital tumors, which
is especially useful in the identification of metastatic tumor deposits, allowing
definitive diagnosis without necessity of open biopsy. FNAB may also aid in evaluation
of lacrimal gland masses, often allowing a cytopathologic diagnosis of inflammation,
lymphoma, pleomorphic adenoma, or carcinoma, allowing planning of more definitive
treatment without the need for an incision biopsy.
The Multidisciplinary Team
The Multidisciplinary Team
FNAB should be conducted by an experienced orbital specialist, ideally with the team
cytopathologist at his or her side to immediately handle and microscopically evaluate
the aspirate, and to guide whether or not additional passes may be required to best
arrive at a tissue diagnosis. Some pathologists may not be well acquainted with typical
orbital pathologic processes and may benefit through a closer clinical relationship
with the orbital surgical team, and/or solicitation of tissue evaluation by more experienced
colleagues; this holds true for incisional and excisional biopsies, as well as FNABs.
TED is the number one cause of proptosis, unilateral or bilateral. In most cases,
a confident clinical diagnosis may be made without the need of an orbital imaging
study ([Fig. 10]). In severe TED with compressive optic neuropathy, or in stable, fibrotic TED with
residual proptosis, noncontrast orbital CT is useful for surgical planning of orbital
decompression. TED patients should be comanaged by an ophthalmologist and an endocrinologist
who will maintain euthyroidism and avoid use of radioactive iodine.
Fig. 10 These three unrelated patients presented with histories and findings allowing secure
diagnoses of thyroid eye disease, without need for orbital echography, computed tomography,
or magnetic resonance imaging.
Lesions which displace the globe or extend to the mid- or posterior orbit should be
assessed by orbital MRI with and without contrast. If the orbital MRI reveals associated
sinonasal or intracranial disease, appropriate otolaryngologic and/or neurosurgical
consultations should be obtained, following which further evaluation and management
should be team based.
Whether the orbital disorder will be observed, treated medically, and/or operated,
the orbital specialist's service does not end at the completion of any surgery. Acute
and convalescent postoperative care is important to minimize complications and optimize
outcomes. Continued involvement in the monitoring and treatment of the patient is
of benefit to the whole team, and, ultimately, to the patient.
Assessment and Plan
An adequate clinical neuro-ophthalmologic examination narrows the differential diagnosis
for a given patient, facilitating a more focused selection of diagnostic testing.
For example, most patients with a secure clinical diagnosis of TED, with no clinical
evidence of compressive optic neuropathy do not require orbital imaging; the focus
of medical attention may remain on assessment and treatment of associated thyroid
disorders and management of the orbital disease, which may include treatment with
teprotumumab.[19]
Illustrative Cases
Case 1
A 39-year-old woman visited an optometrist with a complaint of 1 year of progressive
left frontal headache and left cheek pain. Uncorrected visual acuity was 20/20 oculus
dexter (OD) and 20/80 oculus sinister (OS). Refraction was plano (zero) OD and +3.00
OS, which improved the visual acuity to 20/25. The headache and periorbital pain were
attributed to the refractive difference; a contact lens was prescribed for the left
eye, and the patient's symptoms were resolved. At follow-up, 1 year later, the optometrist
noted mild anisocoria and “indistinct borders” around the left optic nerve, and the
patient was referred for neuro-ophthalmic consultation; 3 mm of left axial proptosis
was measured by exophthalmometry, as well as mild anisocoria, left pupil larger than
right ([Fig. 11]). A left RAPD was found. There was mild discomfort and diplopia in upgaze, in association
with mild restriction of left supraduction. Quantitative perimetry (visual field testing)
demonstrated mild relative generalized depression of sensitivity of the left eye (OS)
([Fig. 12]). Ophthalmoscopy revealed normal findings OD and swelling of the left optic nerve
([Fig. 13]). OCT demonstrated moderate thickening of the RNFL OS, secondary to optic nerve
head edema ([Figs. 14] and [15]). OCT of the RGC layer demonstrated normal findings ([Fig. 16]), suggestive of a good prognosis for recovery of good vision with effective treatment,
as well as choroidal folds ([Fig. 17]). MRI ([Fig. 18]) revealed an enhancing 2 cm diameter left intraconal mass, inferior to the optic
nerve, isointense with brain on T1, and bright on T2. There was expansion of the left
bony orbit, consistent with and suggestive of chronicity. Dynamic B-mode echography
in office demonstrated high internal reflectivity, and easy mobility of the rectus
muscles and optic nerve over the surface of the mass, consistent with a noninvasive
and nonadherent nature. The mass was removed by lateral orbitotomy with no postoperative
morbidity. Tissue diagnosis was cavernous hemangioma.
Fig. 11 The patient had been unaware of mild left proptosis and anisocoria.
Fig. 12 Quantitative perimetry demonstrated (a) visual field of the left eye; (b) mild relative generalized depression of sensitivity of the left eye.
Fig. 13 Ophthalmoscopy revealed normal findings OD (a) and swelling of the left optic nerve (b).
Fig. 14 Optical coherence tomography demonstrated moderate thickening of the retinal nerve
fiber layer (RNFL) OS, secondary to optic nerve head edema.
Fig. 15 Optical coherence tomography demonstrated the cross-sectional swelling of the left
optic nerve head, as well as thickening of the retinal nerve fiber layer (RNFL).
Fig. 16 Optical coherence tomography of the retinal ganglion cell layer demonstrated normal
findings, suggestive of a good prognosis for recovery of good vision with effective
treatment.
Fig. 17 Optical coherence tomography (OCT) further revealed choroidal folds OS, consistent
with compression of the posterior aspect of the globe. The choroidal folds were more
evident in OCT than in ophthalmoscopy or fundus photography.
Fig. 18 Magnetic resonance imaging revealed a large left intraconal mass, inferior to the
optic nerve, isointense with brain on T1 and enhancing homogenously. There was expansion
of the left bony orbit, consistent with and suggestive of chronicity.
Case 2
A 47-year-old woman was aware of diminishing vision of the left eye for 1 year, which
was rapidly worsening over 3 months prior to presentation. She noted intermittent
mild pain of the left eye, especially when flying ([Fig. 19]). Visual acuity was 20/25 OD and 20/50 OS. There was no proptosis, no enophthalmos,
and no hyper- or hypoglobus. She was orthophoric in all gaze positions and ductions
were full. There was a moderate left RAPD. Findings on slit lamp biomicroscopy and
ophthalmoscopy were normal, with neither optic atrophy nor optic nerve head edema
evident. Quantitative perimetry ([Fig. 20]) revealed marked depression of sensitivity OS, especially in the temporal visual
field. Although OCT revealed the RNFL thickness ([Fig. 21]) to be “normal,” there was a significant relative thinning OS in comparison to OD.
MRI ([Fig. 22]) demonstrated an intraconal posterior orbital apex mass, inferior to the optic nerve,
avidly enhancing with contrast. The mass ([Fig. 23]) was removed in entirety by a transnasal endoscopic route and found to be a cavernous
hemangioma. There was a near complete recovery of vision, with only mild generalized
depression of sensitivity evident in quantitative perimetry performed 2 weeks postoperatively
([Fig. 24]).
Fig. 19 A 47-year-old woman complained of progressive loss of vision, OS.
Fig. 20 Quantitative perimetry revealed marked depression of sensitivity OS, especially in
the temporal visual field.
Fig. 21 Although the retinal nerve fiber layer (RNFL) thickness was “normal,” there was a
significant relative thinning oculus sinister (OS) in comparison to oculus dexter
(OD). ONH, optic nerve heads.
Fig. 22 Magnetic resonance imaging demonstrated an intraconal posterior orbital apex mass,
inferior to the optic nerve, avidly enhancing with contrast.
Fig. 23 The mass was removed in entirety and found to be a cavernous hemangioma.
Fig. 24 There was a near complete recovery of vision, with only mild generalized depression
of sensitivity evident in quantitative perimetry performed 2 weeks postoperatively.
Conclusion
Many—perhaps most–patients with orbital disease do not require surgery. Even for those
for whom surgery is the best course of action, adequate clinical evaluation by a neuro-ophthalmologist
or orbital surgeon narrows the differential diagnosis, aids in surgical planning,
and is of great value in improving the accuracy of the preoperative risk–benefit analysis
associated with informed consent. The preoperative clinical evaluation also establishes
baseline for a variety of measures which may be quantitatively and objectively reassessed
postoperatively. In those cases where decline in form or function is documented over
time, an objective impetus for intervention by surgical, radiotherapeutic, or medical
means may be established.
