Ординатура / Офтальмология / Английские материалы / Ultrasonography of the Eye and Orbit 2nd edition_Coleman, Silverman, Lizzi_2006

(isoechoic or hyperechoic with the iris). The B-scan ultrasonogram of a patient with a ciliary body cyst is shown in Figure 3.33. Often the origin of the cyst may be undifferentiable as to iris or ciliary body in nature. However, it is important to distinguish between solid and cystic masses (see Ciliary Body Tumors in later section).

Figure 3.33. Ciliary body retroiridal cyst can be demonstrated in this occult area as clear, usually rounded, single, or multiple cyst spaces. They are nearly always clear acoustically and may, at times, contact the lens and conceivably cause cataract formation.

Figure 3.34. A patient with iris bombé, demonstrating adhesions of the iris sphincter to a cataractous lens.

Iris Bombé/Plateau Iris/Post-glaucoma Surgery

A B-scan ultrasonogram of a patient with iris bombé is shown in Figure 3.34. This iris is pushed forward in a convex fashion. Other iris changes, such as plateau iris (Figure 3.35), have been described by Pavlin et al. (65)

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and by Pavlin and Foster (80). These anatomic changes are best seen with 50-MHz ultrasound. The cause of plateau iris has been established by ultrasound to be the result of an anterior positioning of the ciliary processes that prevents the iris from falling away from the trabecular meshwork following iridotomy.

Figure 3.35. A patient with plateau iris. In plateau iris, the relation of iris to ciliary body and lens as well as corneoscleral angle can be shown and the ciliary processes demonstrated as anteriorly placed. (Top figure: Courtesy of Charles Pavlin, MD.)

The angle between the iris and the cornea can be accurately measured, providing a quantitative gonioscopy to complement visual gonioscopy (Figure 3.36). This can be useful in cases where visualization of the angle is compromised for whatever reason.

Postsurgical evaluation of glaucoma patients includes examining bleb configuration postfiltration surgery and examination of the position of filtration devices, such as an Ahmed valve (Figure 3.37). Iris adhesions may develop, as in Figure 3.38, of a patient with a displaced haptic. The iris remained adherent to the cornea even after the lens had been repositioned (Figure 3.38). The patient's visual symptoms disappeared following lens repositioning.

Figure 3.36. 50-MHz scans demonstrate single planes through the anterior segment that allow the cornea-iridal angle to be measured. Top: This scan shows a patient with closed angle glaucoma. Middle: This scan shows a patient with narrow angle glaucoma. Bottom: This scan demonstrates how lines can be used to actually

measure the angle in different meridians. This is termed digital gonioscopy.

Figure 3.37. Left: 50-MHz scan of a filtering bleb showing the bleb space as well as possible anatomic

changes of underlying sclera, which may include hypotonus changes of separation of the ciliary body from the sclera, as is shown in this figure (arrow).Right: Position of an Ahmed Glaucoma Valve, which

is used to control intraocular pressure, lowering the chance of hypotony.

Figure 3.38. Top: A patient with iris touch noted superiorly and a partially dislocated lens. Middle: This pair of ultrasonograms show the lens and haptic positions. Bottom: These scans show the same eye following lens repositioning. The iris remains adherent to the cornea. (see color image)

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Figure 3.39. A cross section at 50 MHz of the eye demonstrating the variation of ciliary process morphology and position as distinct from the ciliary muscle. The arrow points to the ciliary body, whereas the arrowhead indicates the ciliary processes. Note an anterior vitreal strand (VS), often seen as part of the zonular suspension.

Ciliary Body

The ciliary body can be well defined at higher frequencies. Although there are three muscle groups anatomically, only two are characteristically seen with ultrasound, that is, the sphincter component (Mueller's muscle) and the longitudinal component. In scanning, it is important to distinguish the muscle from the ciliary processes (Figure 3.39), which take various morphologic patterns. The ciliary processes are best distinguished with serial or 3-D scans that allow the base to be identified most easily (Figures 3.40 and 3.41; see also DVD). The processes tend to vary with globe dimensions (i.e., myopic or hyperopic eye) and with age and/or pressure of the crystalline lens or intraocular lens.

Figure 3.40. Serial scans made coronally through the ciliary body, demonstrating ciliary processes in cross

section. Note the cyst in the scan in the upper right. (See also DVD.)

Clinically, we have found several conditions or situations where it is important to distinguish the ciliary

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muscle anatomically. These are tumors, hypotony, accommodation, and glaucoma management. Tumors will be discussed later in the section on ocular tumor, where it is essential to distinguish an iris melanoma from a ciliary body melanoma or to recognize extension of an iris tumor into the ciliary body.

Figure 3.41. A color rendering and 3-D animation of the scan seen in Figure 3.40, further demonstrating the difference of the anatomy of the ciliary body and the processes. (see color image)

Figure 3.42. Separation of the iris from the sclera (iridodialysis) in a patient with an iridotomy and narrow angle.

Hypotony will be discussed later in the section on ocular trauma. It bears pointing out that the separation of the ciliary body from the sclera is a clinically important distinction, whether it be from iridodialysis (Figure 3.42) or an isolated separation (Figure 3.43). The movement of the ciliary body is an important measurement observation as it relates to production of accommodative changes in the lens. Thus, good visualization and measurement of the anatomy are required for both lens implantation, particularly with intraocular contact lenses (ICL) or accommodating lenses, and placement of surgical incisions for presbyopic surgery, whether with implants (Figure 3.44) or by laser (Figure 3.45).