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Video Report

Dynamic Ultrasound Movements of the Eye and Orbit

¹The New York Eye & Ear Infirmary, New York, NY
²New York Medical College, Valhalla, NY
³New York University School of Medicine, New York, NY

Correspondence: Julian PS Garcia Jr, MD, The New York Eye & Ear Infirmary Retina Center, 310 East 14th St, New York, NY 10003, USA
Tel: +001 (212) 614 8343 Email: jgarcia{at}nyee.edu

Date of acceptance: 1st February 2006

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Introduction

Ophthalmic ultrasound instruments display echo-generated B-scan images almost instantaneously. Therefore, "real-time" movements of, within or around a lesion can be accurately depicted.[1] Traditionally, A-scan ultrasonography used to be the diagnostic test of choice for differentiating intraocular tissues, displaying spikes distinct from each other. In practice, these spikes are affected by the position of the probe and can be modified by debris that may be adjacent to its surface, rendering tissue distinction ambiguous. Rather than using A-scan where one does not actually see what tissue interfaces are being encountered by the ultrasound waves, dynamic B-scan imaging reveals the sequence of tissue movement in a more direct, visual and logical way.

Dynamic 2D B-scan ultrasound recording brings the element of motion within the realm of digital image capture, playback, storage, retrieval and analysis.[2] Consequently, recorded dynamic 2D images of ocular pathologies can be reviewed by others in the ophthalmic team, even in the absence of the patient, for diagnostic verification or surgical planning.[3] This prospective case series demonstrates the unique diagnostic value of dynamic 2D B-scan ultrasound recording in selected cases of ophthalmic disease.

Methods

Anterior ocular 2D B-scan ultrasound recording was performed with a water-immersion technique using a 35-50 MHz high frequency probe. Posterior segment and orbital disease was imaged through the lids or directly on the eye using a 12 or 20 MHz B-scan probe. These probes were attached to the OTI-Scan 1000 Ultrasound Tomography System (Ophthalmic Technologies Inc. [OTI], Toronto, Ontario, Canada). For each case, two to three sequences of real-time digital video recordings were obtained, analyzed and correlated with clinical records.

Comments

Dynamic ultrasound recording vividly captures the three basic forms of motion described in literature, namely convection, aftermovement, and vascularity. In addition, we present gravity-dependent and reflex movements in this study.

Convection is slow, spontaneous motion representing convection currents of fine particles within a cavity. This is observed in hemorrhagic cyst, as well as in long-standing vitreous hemorrhage (Video 1) and endophthalmitis.

Aftermovement is motion following cessation of eye movement. Here, we examine the quality of vitreous, retinal and choroidal movements.

The vitreous and posterior hyaloid typically display a wave-like, undulating aftermovement. This is seen in asteroid hyalosis, as well as in partial or complete posterior vitreous detachment. It is interesting to note that the posterior hyaloid is clearly visible when serous fluid is behind it (Video 2), and becomes indistinct in the presence of subhyaloid hemorrhage. Aftermovement of the posterior hyaloid becomes shaky rather than undulating in chronic uveitis, and can even be absent in some cases.

The retina generally exhibits varying degrees of mobility. It can be relatively shaky and jiggly (Video 3), or may exhibit gradually shifting (Video 4) aftermovement. These findings are evident in open funnel retinal detachment (RD) of recent or chronic onset, rhegmatogenous RD, and tumor-induced RD. Chronic close funnel RD shows no retinal aftermovement.

Retinal aftermovement can also mimic the undulating aftermovement of the vitreous. This may be observed in a retinal flap tear or in a detached retina secondary to a hole, where vitreous still adheres to the tip of the retinal break.

In contrast to the vitreous and retina, the choroid is less sinuous. Dome-shaped choroidal detachments usually have no aftermovement, be it serous or hemorrhagic type. Rarely do they show motion, resembling the jiggly aftermovement of the retina. In kissing choroidal detachments, aftermovement of blood within the choroid may be appreciated (Video 5). One should beware of this variety as kissing choroidals may mask the presence of a tumor eg, choroidal melanoma.

Not all choroidal detachments are dome-shaped. There are low-lying ones secondary to serous or hemorrhagic choroidal effusion. Typically peripheral in location, these may or may not exhibit the jiggly aftermovement of the retina.

Vascularity is rapid, spontaneous motion signifying blood flow within vessels. This feature is sought after in ophthalmic tumor assessment. Large choroidal melanomas demonstrate a distinctive type of shimmering, twinkling motion within the mass (Video 6), which usually disappears months to years following successful radioactive plaque therapy. In contrast, a more pulsatile type of internal vascularity is observed in orbital aneurysms (Video 7). Gravity-dependent movement is induced by eye or head motion following gravity. An orbital varix enlarges dramatically as the patient bends his head at the waist, and shrinks dramatically as the patient straightens up (Video 8). This can also be elicited by Valsalva maneuver.

Last, but not least, is reflex movement triggered by exposure to light or dark in tests performed for evaluation of the anterior chamber angle. In narrow angle glaucoma, the angle between the cornea and iris is narrow and slit-like in a lighted room. As light is turned off, the iris shortens as the pupil dilates, and the angle becomes occluded (Video 9). In pigmentary dispersion syndrome, the angle is wide open. The degree of contact between the posterior iris surface and the anterior lens surface is minimal in a dark room. As light is switched on, the iris lengthens as the pupil constricts, and the iris sags rubbing against the zonules at the peripheral surface of the lens (Video 10).

Overall, dynamic ultrasound recording offers distinct advantages that "still" B-scan images cannot provide. Specifically, the element of motion reveals what intraocular structures were involved, the nature of tissue movement, its flexibility and patterns of internal vascularity. Movies allow for a unique ability to observe minute details of motion, playing a major role in the differential diagnosis of ophthalmic disease. Among the ophthalmic imaging armamentarium to date, only dynamic 2D B-scan ultrasound recording has the sole capacity for repetitive analysis, storage and subsequent reporting of various tissue movements observed in the eye and orbit.

Conflict of Interest Statement

The authors have no proprietary interest in the study.

This study is supported (in part) by The New York Eye & Ear Infirmary and The EyeCare Foundation Inc., Research to Prevent Blindness, New York City.

References

• Greene R, Byrne SF. Ultrasound of the Eye and Orbit, ed 2. Philadelphia, Mosby, 2002, pp.35-37.
• Rosen RB, Dunne S, Garcia JPS. 3D-Ultrasound Tomography. In: Ciulla T, Regillo C, Harris A, eds. Retina and Optic Nerve Imaging. Philadelphia: Lippincott Williams & Wilkins; 2003: 137-162.
• Coleman DJ, Jack RL. B-scan ultrasonography of the retina and vitreous. Int Ophthalmol Clin 1976;16(1):31-43.