Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmic Echography_Harrie_2008

SF is a 42-year-old woman who was noted on a routine eye examination to have peripapillary hemorrhage just inferior to her left optic disc. Visual field testing showed a focal arcuate defect superior to the blind spot. A fluorescein angiogram did not reveal any subretinal neovascularization.

B-scan demonstrated a tiny druse buried in the optic nerve head (Fig. 20) that was assumed to be the source of the hemorrhage and the patient was told to follow-up in 4 months unless any symptoms of visual loss or distortion occurred.

Echo spikes from calcium within the nerve substance, such as with calcified drusen, stand out in contrast to the relatively lower reflective nerve parenchyma. The same explanation applies to high reflective material within the optic nerve vasculature as sometimes found in central retinal artery emboli. Sergott and colleagues7 reported that 31% of patients with central retinal artery occlusions were found to have embolic material posterior to

the lamina cribrosa on B-scan evaluation with a color Doppler unit. These can also be demonstrated on a standard grayscale B-scan unit.

FIG. 20. B-scan of tiny buried druse (arrow)

CL is a 70-year-old man who presented with the history of marked reduction of vision in his left eye several days ago. Examination found vision 20/30 OD and OS of hand motions at 1 meter. He had a 3+ afferent papillary defect in this eye. Slit-lamp examination was normal and fundus examination found some narrowing of the retinal arterioles and a faint reddish appearance to the central macula. It was assumed that a vascular event had occurred and a workup was done including erythrocyte sedimentation rate, C-reactive protein, complete blood count (CBC) with platelet level, antiphospholipid antibodies, plasma homocysteine, and a carotid duplex scan. These tests were unremarkable except for 50% stenosis of both carotid arteries.

He was referred for orbital color Doppler testing. The grayscale B-scan part of the study showed a small high reflective signal in the optic nerve posterior to the lamina cribrosa in the area of the central retinal artery (Fig. 21). This was consistent with embolic material within the artery most likely originating from an atheromatous plaque in the carotid artery, but a cardiac source could not be ruled out so an echocardiogram was performed and interpreted as normal. A carotid angiogram confirmed an ulcerated atheroma from which the embolus had most likely come. The patient was given the option of medical antiplatelet therapy with aspirin or a surgical endarterectomy.

The sensitivity of echography in detecting intraocular calcification with optic nerve drusen is equally important in the evaluation of leukocoria to eliminate retinoblastoma. The detection of a

mass in a small child has ominous implications regarding morbidity and mortality. There is a long differential diagnosis for leukocoria, but the presence of calcium in a mass found within a child’s eye is almost pathognomonic for retinoblastoma. However, according to Bullock et al.,8 it is absent in about 10% of retinoblastomas so any intraocular mass in a child must be viewed with suspicion. CT scans accurately detect calcium when it is present in a moderate amount, but can miss it when only small scattered deposits are present within the tumor. Wilson states, “more than one imaging modality should be used in the evaluation of suspected retinoblastoma, as calcification may be absent on the computed tomography but present on B-mode ultrasound.”9 MRI scans are not able to detect calcium in these tumors.

FIG. 21. B-scan of embolic material in central retinal artery (arrow). (Photo courtesy of Dr Robert Sergott)

TM is a 2-year-old child who was noted by his parents to have a “wandering” left eye that worsened over several months. They consulted with an ophthalmologist who documented an esotropia of 30 prism diopters and found leukocoria on testing the right red reflex. She noted a whitish pink intraocular mass encroaching on the temporal macula on fundus examination. She suspected a retinoblastoma and obtained a CT scan for confirmation. No calcium was detected on the scan (Fig. 22) so she referred the child for echography.

B-scan demonstrated a subretinal mass in the temporal fundus that measured 4.6 mm thick by 8 mm by 7mm in basal dimensions (Fig. 23). Multiple tiny high reflective signals were seen within the lesion consistent with fine calcification. The diagnosis of retinoblastoma was established and the child was referred to an oncologist for further workup and treatment.

Some pediatric ophthalmologists are now referring children suspected of having retinoblastoma directly for echography and bypassing CT. The optic nerve and brain are then imaged by MRI to rule out intracranial extension of the lesion.10

Echography is an excellent screening tool in the office for orbital problems such as proptosis. The most common cause of both bilateral and unilateral proptosis is Graves’ disease and echography is a very sensitive and specific modality to evaluate the extraocular muscles. B-scan can demonstrate qualitative muscle enlargement although not to the degree achievable on CT and MRI scans. A-scan adds a quantitative dimension by providing a means to accurately measure muscle thickness. In addition, the analysis of the A-scan spikes within the muscle

FIG. 22. Computed tomography scan of retinoblastoma (arrow)

gives tissue signatures that are characteristic for Graves’ as contrasted to other causes of muscle thickening, such as myositis.

FIG. 23. B-scan of retinoblastoma (arrow)

JC is a 32-year-old woman who noted increasing prominence of her right eye over several months. She presented to her primary care doctor, who ordered thyroid tests (TSH and T4) that were normal. He then ordered a CT scan that was interpreted as normal by the radiologist with no mass lesions detected and extraocular muscle thickness “within normal limits.” She was referred to an ophthalmologist who documented possible lid lag on the right side and exophthalmometry readings of 19 mm OD and 16 mm OS. She was referred for echography. A-scan revealed several muscles in both orbits that were greater than upper limits of normal for muscle thickness. The internal reflectivity pattern of these muscles was heterogeneous and consistent with Graves’ disease (Fig. 24). Thyroid antibody testing was performed and was moderately positive. She was instructed about her disease and how to manage any symptoms that may occur, such as puffy lids and dry, scratchy eyes. She was scheduled for a follow-up examination in 6 months and warned about symptoms of optic nerve compression, and was specifically told to check her color sensitivity to a red object at home.

The extraocular muscles may also be thickened in cases of orbital myositis but the A-scan is quite helpful in viewing the internal structure, which can clarify the differential diagnosis of the enlarged muscle. This capability of internal analysis is especially valuable in cases where the muscle is not abnormally enlarged.

FIG. 24. A-scan of extraocular muscle involved by Graves’ disease (vertical arrows)

CJ is a 26-year-old man who noted the rapid onset of painful swelling of his right upper and lower eyelids. He was seen at the emergency room and a CT scan was felt to be consistent with mild sinusitis and a preseptal cellulitis and he was given intravenous (IV) antibiotics and sent home on an oral agent. His symptoms improved over several days but then similar symptoms occurred in his left eye. He was seen again at the emergency room and the ophthalmologist on call was asked to come in.

Examination showed slight left upper lid swelling and two prism diopters of left esotropia with some pain on abduction. The CT scan was reviewed and the extraocular muscles appeared subjectively normal in thickness. Echography was later performed and the A-scan measured normal muscle thickness, but the left lateral rectus was low to medium and regular reflective compared to the higher and more irregular reflectivity of the right lateral rectus. This was interpreted as being consistent with inflammatory infiltration (Fig. 25). The patient was started on indomethacin with resolution of his symptoms over the next several weeks.

Orbital tumors usually present with proptosis and/ or globe displacement in the vertical plane. Also, the presence of choroidal or retinal folds is sometimes associated with a retrobulbar mass although they are often idiopathic and these patients can be spared unnecessary CT or MRI scanning by a brief screening ultrasound examination in the office.

FIG. 25. A-scan of extraocular muscle involved by myositis (vertical arrows)

PR is a 26-year-old man who noted some blurring of the vision in his right eye and scheduled an evaluation by his optometrist. Examination found vision 20/25 OD and 20/15 OS. There was mild distortion of the vision in the OD to amsler grid testing. The slit-lamp examination was unremarkable, but the fundus examination showed moderate choroidal folds in the right eye. An orbital tumor was suspected and the patient underwent CT scanning that did not demonstrate a mass and was reported as normal. The patient sought a second opinion from the oculoplastic service at the university medical center.

Ultrasound was performed and no orbital mass was detected by either A- or B-scan. However, there was some subtle flattening of the globe consistent with idiopathic choroidal folds (Fig. 26).

However, choroidal folds can be the result of compression of the posterior wall of the globe by an orbital mass. Such lesions can be detected and characterized at the time of the initial examination with

timely referral of the patient for directed follow-up studies and optimal management by a specialist.

FIG. 26. B-scan of flattening of posterior globe wall (arrows)

RJ is a 56-year-old woman who was told by her daughter that her right eye “looked bigger than her left.” She consulted her primary care doctor who told her she probably had Graves’ disease because of a history of thyroid problems, including treatment for hyperthyroidism with radioactive iodine 131 a number of years ago. An ophthalmologist was consulted who performed an examination and confirmed the presence of 5 mm of proptosis in her right eye. The remainder of the examination was normal including visual acuity in both eyes of 20/20.

B-scan showed an oval encapsulated intraconal mass of over 20mm in diameter. A-scan demonstrated

high internal reflectivity in the anterior part of the lesion with a progressive decrease in spike height towards its posterior aspect (Fig. 28). No spontaneous vascularity was noted and the tumor decreased in size about 20% when moderately firm pressure was applied with the ultrasound probe against the globe. These findings were highly consistent with a cavernous hemangioma and subsequent surgical excision confirmed this diagnosis.

Lacrimal gland enlargement by inflammatory or neoplastic involvement is a relatively common cause of temporal lid swelling in mild cases with inferior displacement of the globe in moderate-to- severe involvement of the gland.

KR is a 28-year-old man who noted some fullness in the outer part of his left upper lid. He thought he could feel some firmness and mild tenderness just below the upper outer rim of the orbital bone. Examination by his ophthalmologist confirmed these findings with inferior displacement of the globe by 2 mm. Echography was performed in the office and showed enlargement of the left lacrimal gland to 18.5 mm and high internal reflectivity, which became lower as the spikes traveled across the gland (Fig. 29). This was suspicious for a benign mixed cell tumor and he was referred for CT scanning and then to an orbit surgeon for an en bloc excision of the lacrimal gland.

Anterior orbital lesions can involve the eyelids with resultant swelling. Echography is a very useful office test to quickly screen for such lesions with some posterior extension back into the orbit. A relatively common tumor in children with such presentation is the infantile or capillary hemangioma.

This can grow rapidly with a doubling time of weeks and must be differentiated from more serious tumors such as rhabdomyosarcoma.

FIG. 29. A-scan of pleomorphic adenoma of the lacrimal gland (vertical arrows)

SF is a 6-month-old girl who was noted by her parents to have a fullness of her left lower lid that increased when she was crying. This had become more prominent over a few weeks to the point that several relatives had commented on it. The pediatrician was consulted and he ordered a CT scan that showed some nonspecific fullness of the lid but no distinct mass was seen. The child was referred to an ophthalmologist who performed an ultrasound.

A-scan showed a moderately soft lesion measuring 15.5 mm in anterior-to-posterior dimensions with irregular internal reflectivity (Fig. 30). An obstetrical acoustic Doppler unit with a small probe adapted for the orbit demonstrated rapid arterial blood flow within the more central part of the lesion. These findings were highly consistent with an infantile or capillary hemangioma and she was referred to a pediatric ophthalmologist for steroid injection into the tumor.

Echography has the highest specificity of all the imaging studies for the diagnosis of infantile hemangioma. The irregular internal reflectivity on A-scan is a result of the tissue architecture of these lesions with cellular areas (lower reflectivity) interspersed with vascular channels (Fig. 31). They typically demonstrate relatively high arterial blood flow on Doppler studies as opposed to the stagnant venous flow of the cavernous hemangiomas seen in older children and adults. They may be found in the posterior orbit but more commonly present as a “strawberry” lesion visible under the eyelid skin.