Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Five The Skull 655
Fig. 5-57 Transverse sonograms of
the eyes of a 5-year-old mixed breed
male dog brought in for evaluation
of glaucoma (A), and of a 3-year-old
spayed female mixed breed dog
brought for evaluation of cataract
with poor light response (B). A
curvilinear echogenic structure is
visible in the vitreous chambers in
both dogs. This structure can be
traced caudally to the region of the
optic disc. This represents a detached
retina. Diagnosis: Retinal detachment.
A
B
A
B
Fig. 5-58 Longitudinal (A, C, and
D) and transverse (B) sonograms of
the right eye of a 12-year-old spayed
female mixed breed dog with a history
of exophthalmos and retrobulbar
swelling of 3 weeks duration.
There is a hypoechoic, irregularly
shaped mass in the retrobulbar space
(black arrows). This represents a
retrobulbar tumor or abscess. There
is irregularly shaped echogenic
material in the vitreous chamber
(white arrows). This is indicative of
asteroid hyalosis. Diagnosis:
Retrobulbar carcinoma.
C
D
U LT R A S O N O G R A P H Y O F T H E R E T R O B U L B A R A R E A
Ultrasonography is useful for examining the retrobulbar area. 34,167 Bony masses arising from
the skull in this area may not be delineated fully by ultrasonography. 168 The examination may
be performed by placing the transducer on the cornea and imaging the retrobulbar area
through the eye. The transducer also may be positioned dorsal to the zygomatic arch and
caudal to the eye to examine the retrobulbar area directly. Both transverse and longitudinal
planes should be used. The area behind the eye usually is well defined with structures (e.g.,
optic nerve, extraocular muscles, and fat) in the orbital cone and a uniformly heteroechoic
tissue around the orbital cone. Lesions may be hyperechoic or hypoechoic and diffuse or well