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AJR 2006; 187:1061–1072

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© American Roentgen Ray Society

M E D I C A L I M A G I N G

A C E N T U R Y O F

M E D I C A L I M A G I N G

A C E N T U R Y O F

Bedi et al.Sonography of the Eye

H e a d a n d N e c k I m ag i n g • P i c t o r i a l E s s ay

Sonography of the Eye

Deepak G. Bedi1

Daniel S. Gombos2

Chaan S. Ng1

Sanjay Singh3

Bedi DG, Gombos DS, Ng CS, Singh S

Keywords: eye sonography, ocular imaging, ocular melanoma, ocular sonography

DOI:10.2214/AJR.04.1842

Received December 3, 2004; accepted after revision August 31, 2005.

1Department of Radiology, The University of Texas M. D. Anderson Cancer Center, Box 57, 1515 Holcombe Blvd., Houston, TX 77030. Address correspondence to D. G. Bedi (dbedi@di.mdacc.tmc.edu).

2Department of Ophthalmology (Plastic Surgery), The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030.

3Department of Radiology, Methodist Hospital, Houston, TX 77030.

CMEThis article is available for 1 CME credit. See www.arrs.org for more information.

OBJECTIVE. The purpose of this study is to show how sonography can reveal pathologyof the eye and to highlight its usefulness as a simple and cost-effective tool in investigatingeye symptoms.

CONCLUSION. The cystic nature of the eye, its superficial location, and high-frequencytransducers make it possible to clearly show normal anatomy and pathology such as tumors, ret-inal detachment, vitreous hemorrhage, foreign bodies, and vascular malformations. Sonographyis useful as a treatment follow-up technique because it has no adverse effects. Sonography is welltolerated by patients and relatively easy to perform for those familiar with real-time sonography.

he superficial location of the eye,its cystic composition, and theadvent of high-frequency ultra-sound make sonography ideal

for imaging the eye [1]. MRI is favored byradiologists, so there are few reports on oc-ular sonography in the radiology literature[2, 3]. Sonography is used more commonlyby ophthalmologists to evaluate the eye,particularly when direct examination byslit-lamp and funduscopy is not sufficient.Detailed cross-sectional anatomy of the en-tire globe is possible with conventionalsonographic equipment [1–4]; anteriorchamber visualization requires a dedicatedsonographic biomicroscope [5]. Color Dop-pler and A-mode sonography [1, 6] are re-ported to be useful in characterizing masses.The sonography examination is rapid andcost-efficient, without the contraindica-tions, such as pacemakers, that MRI has.Sonography avoids the irradiation associ-ated with CT and the need for sedation inchildren [7]. Therefore, it can be used re-peatedly during treatment of tumors to as-sess response to therapy.

TechniqueConventional gray-scale sonographic equip-

ment (Elegra, Siemens Medical Solutions;ATL, Philips Medical Systems) and 7.5–15-MHz transducers were used by the radiol-ogy department, scanning through theclosed eyelid (Fig. 1A). The ophthalmologydepartment used a 10-MHz B-mode probe

and an 8–10-MHz A-mode probe (Innova-tive Imaging Systems), scanning throughthe open eye after paralyzing the blink re-flex (Fig. 1B). A dedicated ocular sono-graphic biomicroscope, using frequenciesup to 50 MHz (Fig. 1C), was available for alimited time.

In the illustrations shown here, the radiol-ogy transducers were linear and the imagesare axial in a traditional anterior-to-poste-rior orientation. Ophthalmology used sectortransducers, and their images are also axialbut rotated in a left-to-right orientation toshow the A-mode echo patterns. The term“reflectivity” is used in some figure legendsto describe A-mode echo patterns and issimilar to the term “echogenicity,” but in ad-dition describes amplitude of tissue inter-face reflection.

Normal AnatomyThe cornea, conjunctiva, anterior cham-

ber, posterior chamber. and iris (Figs. 2and 3) rarely require sonography and arenot well visualized with conventionalsonography, but they are excellently de-tailed with newer sonographic biomicro-scopes. The lens is best inspected directly,with no need for sonography. A mature cat-aract of the lens may obscure the retina onfunduscopy, necessitating sonography. Thevitreous body is gelatinous and anechoic,with loose attachments to the retina, and itstabilizes the eyeball. The choroid is partof the uveal tract, which also includes the

T

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A

Fig. 1—Technique for sonography of eye.A, Radiologists use compact “hockey-stick” linear transducer with patient’s eyelid closed. Small amount of gel is sufficient for posterior eye anatomy; standoff pad or abundant gel can be used for anterior chamber. B, Ophthalmologists perform examination after paralyzing blink reflex and scan open eye.C, Ultrasound biomicroscope transducer, operating at 50 MHz, scans through water bath (arrow), incorporated into transducer, which is placed on open eye.

B C

Fig. 2—Axial cross-section of eye and diagrammatic representation of pathology. C = cornea, A = anterior chamber, L = lens, V = vitreous body, CH = choroid, CB = ciliary body, I = iris, R = retina, S = sclera, CRA = central retinal artery, ON = optic nerve, PCA = posterior ciliary arteries. Sonographic anatomic correlation is shown in Figure 3; some vascular structures are seen only in Figures 3 and 16.

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ciliary body and iris, and is the site ofmany intraocular tumors. The choroid has

a rich vascular supply from the long andshort posterior ciliary arteries. Because

the retina is pigmented, direct inspectionof the choroid by funduscopy is limited,

A B

C

Fig. 3—Normal eye anatomy.A and B, Axial sonograms show normal anterior chamber (A), lens (L), choroid (CH), ciliary body (CB), iris (I), and sclera (S) in A and V = vitreous body (V) and optic nerve (ON) in B.C, Axial color Doppler sonogram shows normal central retinal artery (CRA).

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and sonography plays an important role indiagnosing choroidal melanoma and meta-

static tumors. The retina and choroid aresonographically perceived as one layer in

the normal eye; the sclera is a highly re-flective outer layer.

Fig. 4—34-year-old man with cystic lesion of iris (arrow), illustrated with use of standoff gel pad to visualize anterior eye anatomy. C = cornea, A = anterior chamber, P = posterior chamber, V = vitreous body.

Fig. 5—47-year-old man with iris melanoma. Ultrasound biomicroscopic image provides better anatomic detail of anterior portion of eye than conventional sonogram shown in Figure 4.

A B

Fig. 6—52-year-old woman with choroidal melanoma. A, Typical sonographic features include hypoechoic mass, lobular in shape, with marginal retinal elevation (large arrow). Hyperechoic rim is combination of elevated retina and peripheral blood vessels. Characteristic hypoechoic echotexture is also seen in A-mode scan (graph at bottom), which shows decreased reflectivity between two small arrows corresponding to margins of mass, a feature that sometimes helps distinguish it from other types of tumor (see Figs. 13–15).B, Funduscopy shows large dark melanoma (large arrows) with peripheral retinal elevation (small arrows), which appears translucent yellow because red color of underlying choroid, seen elsewhere, is lost.

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The retina has a rich blood supply from thecentral retinal artery, which is clearly seen oncolor Doppler sonography, as are the adjacentposterior ciliary arteries that supply the chor-oid and the optic disk. The optic nerve is vis-ible sonographically as a hypoechoic bandstarting at the scleral zone and extending pos-teriorly and medially.

PathologyLesions of the Iris

Cystic or solid lesions of the iris are difficultto show on conventional equipment (Fig. 4) butare well detailed on dedicated ultrasound biomi-croscopic imaging (Fig. 5). This equipment, op-erating at 50 MHz or sometimes higher, has aresolution of 30 µm, far in excess of CT or MRI.

Malignant MelanomaMalignant melanoma (Figs. 6–8) is the

most common primary intraocular tumorand occurs more often in the choroid than inthe iris or ciliary body. Iris melanomas cancause secondary glaucoma. Ciliary bodymelanomas may cause changes in accom-modation from lens displacement. Choroi-

Fig. 7—45-year-old woman with ciliary body melanoma. A, Sonogram shows tumor is large and round, which is common for melanoma. C = ciliary body, A = anterior chamber.B, Color Doppler sonogram shows blood vessels (arrows) encircling and penetrating tumor.C, Ophthalmoscopy shows dark tumor (arrows) partially obscuring normal “red reflex” of retinochoroidal pigmentation seen through dilated pupil.

A B

C D

Fig. 8—62-year-old man with melanoma (arrow) arising from ciliary body (C), which is small and buttonlike. Small melanoma of ciliary body can be missed because of its small size and location if funduscopy is performed without depressing sclera externally.

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dal tumors present with decreased visualacuity and visual field defects. A small mel-anoma of the ciliary body (Fig. 8) can bemissed if funduscopy is performed withoutdepressing the sclera externally. Melanomasof the eye are usually rounded, hypoechoic,and very vascular. They can be complicatedby retinal elevation and vitreous hemor-rhage (Figs. 9 and 10).

Vitreous HemorrhageVitreous hemorrhage spreads diffusely in

the gelatinous vitreous, obscuring the opticdisk, and does not form a fluid meniscus un-less the bleeding is in the space around thevitreous. The causes of vitreous hemorrhageinclude vitreous detachment, diabetic retin-opathy, retinal microaneurysm, trauma, andvascular tumors. The patient complains of“black rain” and has reduced visual acuity.The hemorrhage is absorbed slowly, and theclinical course depends on the exact cause.If choroid tumors are large or near the opticdisk (Fig. 11), enucleation of the eye issometimes necessary. However, brachyther-apy—that is, radiation plaques [8] placedoutside the sclera adjacent to the tumor—isthe preferred mode of treatment (Fig. 12).

Metastasis and LymphomaMetastasis to the choroid is most common

from the breast, lung, and unknown primary

Fig. 9—Complications of melanoma in 56-year-old man with blurred vision. Retinal elevation (small arrows) is caused by tumor mass (large arrow) or by possible transudation of fluid.

Fig. 10—Complications of melanoma in 69-year-old woman with diminished brightness of vision. Vitreous hemorrhage, seen as low-level echoes filling vitreous body (V), completely obscures direct view of tumor (arrow) by funduscopy.

Fig. 11—Complications of melanoma in 42-year-old man with severe loss of vision in one eye. Location of melanoma (large arrow) on and adjacent to optic disk (small arrows) may prevent radiation treatment and could necessitate enucleation of eye.

sites (Figs. 13 and 14). Metastatic tumors arediscoid in shape and hyperechoic comparedwith melanoma. A-mode sonography shows thedifference in echogenicity (also called “reflec-tivity” in ophthalmology literature; see Figs. 6and 13) between melanomas and metastases.Lymphoma can occur in isolation or as metasta-sis to the choroid or the vitreous body (Fig. 15).

RhabdomyosarcomaRhabdomyosarcoma is the most common

primary malignancy of the orbital cavity inchildren, presenting with proptosis, inflam-mation, and loss of vision. A combination ofradiation and chemotherapy makes a curepossible in many cases. Sedation for re-peated CT or MRI during follow-up was

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A B

Fig. 12—55-year-old man with choroidal melanoma.A, Sonogram shows melanoma (M) before brachytherapy (radiation plaque treatment). Melanoma is biconvex, with slight elevation of retina (arrow) at one margin because of serous fluid transudate. B, After radiation plaque treatment, tumor (M) shows significant decrease in volume. Apical tumor dimensions can be obtained using A-mode sonography (not shown).

Fig. 13—50-year-old woman with primary breast cancer metastasizing to eye. Although flat hyperechoic tumor (long arrow) is morphologically similar to lymphoma (Fig. 15) or treated melanoma (Fig. 12), its surface is more irregular, and A-mode sonography (tracing at bottom) shows high reflectivity (short arrows).

avoided in the child shown in Figure 16 byusing sonography.

HemangiomaHemangioma is the most common benign

tumor of the orbital cavity and can be capillary(in children) or cavernous (in adults, Fig. 17).

RetinoblastomaRetinoblastoma is the most common pri-

mary intraocular malignancy of childhood[9] (Fig. 18), often occurring before theage of 3 years, and presenting with a whitepupil (leukocoria) and strabismus. Retino-blastoma is quite vascular and can invade thevitreous body.

Microphthalmos and ColobomaMicrophthalmos and coloboma are con-

genital anomalies caused by incomplete fu-sion of the optic cup in the sixth week of preg-nancy. They cause a posterior eyeball defectwith a posterior orbital cyst and an abnor-mally short eye (Fig. 19).

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A B

Fig. 14—67-year-old man with metastatic adenocarcinoma from unknown primary site. A, Tumor is flat hyperechoic mass (arrows), well seen sonographically in nasal field of rotated eyeball. B, MR image shows subtle, isointense flat mass in nasal aspect of right eye (arrow), which is best seen on this T1-weighted image; T2-weighted images showed similar intensity for tumor and adjacent orbital fat.

Fig. 15—38-year-old woman with lymphoma. Sonography depicts rather flat mass of moderate echogenicity (long arrow). A-mode sonographic tracing, taken through black-line axis, shows moderate reflectivity (short arrows) that iSs greater than that of melanoma (low reflectivity) but less than that of metastasis (high reflectivity).

Foreign BodiesForeign bodies can be metallic, plastic, or

wood. The bodies usually lodge in the con-junctiva or cornea, and the diagnosis is madeby direct examination. Occasionally pene-trating through the cornea (Fig. 20), metallicforeign bodies may lodge anywhere up to theretina and can cause severe inflammationand infection.

Asteroid HyalosisAsteroid hyalosis (Fig. 21) is character-

ized by the presence of minute opacities dueto calcific deposits in the vitreous body,mainly in patients with diabetes and hyper-cholesterolemia. It is usually unilateral andrarely bothersome to the patient, but it canobscure the examiner’s view of the fundus. Ifvisual acuity is affected, the deposits are re-moved by vitrectomy.

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A BFig. 16—2-year-old boy with rhabdomyosarcoma of extraocular muscle. A, Hypoechoic, conical tumor (short arrows) is seen posterior to eye and slightly superior to optic nerve (long black arrow). Retinal detachment is also present (white arrow). Advantages of sonography in this infant outweigh those of MRI because sedation was avoided with minimal loss of anatomic information.B, Color Doppler sonogram shows that despite tumor infiltration around optic nerve (arrows), blood flow through central retinal artery (CRA) and posterior short ciliary arteries (PCA) is intact.

A

Fig. 17—37-year-old man with hemangioma of orbit. A, Nasal superior location is common, as seen on this sonogram, which shows superior ophthalmic vein (black arrow) draining hemangioma (white arrows). B, IV contrast-enhanced CT scan of orbits shows prominent draining vessels (arrows) more clearly than sonogram, but repeated irradiation from CT during follow-up was avoided by using sonography, which provided satisfactory images and flow information. C, Color Doppler sonogram shows blood flow of mixed color (arrows), indicating some turbulence in larger vessels of hemangioma in medial aspect of image. Draining ophthalmic vein seen on gray-scale images and CT is not visible, presumably because of low-velocity flow.

B C

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A BFig. 18—1-year-old girl with retinoblastoma. A, Irregular shape of tumor (short arrows) is hard to outline on this sonogram, but hyperechoic calcific foci (long arrow) are characteristic of retinoblastoma. B, Large retinoblastoma is cream-colored on funduscopic image and partly overlies optic disk (arrow).

A B

Fig. 19—37-year-old man with microphthalmos and coloboma. A, Axial left-to-right sonogram shows abnormally short length of eye (double arrow), posterior defect or coloboma (single arrow), and cyst (C) behind eye. B, Abnormality, particularly cyst (C), is better detailed on axial MR image although coloboma is clearer on sonography.

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Fig. 20—32-year-old male iron foundry worker with foreign body in eye, which appears as hyperechoic focus (arrow) in vitreous body of eye.

Fig. 21—72-year-old man with asteroid hyalosis. Sonogram shows scattered hyperechoic foci (arrow) in central vitreous body.

Fig. 22—58-year-old man with optic disk drusen. Sonography shows characteristically hyperechoic spots at fundus (arrow) and is particularly helpful in revealing drusen buried in optic nerve, which are otherwise invisible on funduscopy.

Fig. 23—42-year-old man with retinal detachment. Sonography shows severe posterior, central detachment (arrow). See Figures 6 and 9 for other examples of detachment.

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Optic Disk DrusenOptic disk drusen (Fig. 22) are calcified lob-

ular bodies in the tissues of the optic disk andnerve that are bilateral in most cases. Usuallyasymptomatic, optic disk drusen can cause vi-sual field defects if buried deep in the diskbecause of compressive atrophy of nerve fibers.

Retinal DetachmentRetinal detachment (Fig. 23) is a sepa-

ration of the neurosensory retina from theunderlying pigmented layer. This condi-tion can be asymptomatic for a long time,then presents with flashes of light, float-ers, “black rain” (if there is accompanyingvitreous hemorrhage), a dark shadow, orloss of visual acuity, depending on the ex-act location and severity of the detach-ment. The three types are based on thecause: Rhegmatogenous detachment—thatis, associated with a retinal tear—is themost common type and is seen with ad-vancing age, a familial disposition, and as-sociated myopia. Tractional detachment

originates in adjacent vitreous strands. Ex-udative detachment is due to fluid, blood,or lipids behind the neurosensory retinaand can be associated with tumors of thechoroid.

ConclusionSonography of the eye shows a variety

of diseases with remarkable clarity. Thetechnique is more cost-efficient than otherdiagnostic techniques and is well toleratedby the patient. We have experienced nolimitations and have received no com-plaints from patients. We do not advocatethe routine use of sonography in theasymptomatic eye, but it may serve as auseful extension of the initial investigationof the symptomatic patient.

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F O R Y O U R I N F O R M A T I O N

This article is available for 1 CME credit. See www.arrs.org for more information.