Full text of DOI:10.1007/s004170100370

Graefe’s Arch Clin Exp Ophthalmol
(2001) 239:968–971
S H O RT C O M M U N I C AT I O N
DOI 10.1007/s004170100370
Alexander Kirchhoff
Oliver Stachs
Rudolf Guthoff
Three-dimensional ultrasound findings
of the posterior iris region
Abstract Purpose: The aim of this
study was to assess the benefit of the i.e. iris cysts, ciliary body cysts and
three-dimensional ultrasound biomi- solid tumours of the ciliary body and
croscopy in examination of the pos-
terior iris and ciliary body.
terations of the posterior iris region,
Received: 14 February 2001
Revised: 15 May 2001
Accepted: 24 August 2001
Published online: 9 November 2001
© Springer-Verlag 2001
iris. Conclusions: The three-dimen-
sional ultrasound biomicroscopy
Methods: Three-dimensional visuali- yields extended diagnostic findings
sation of the anterior eye section was regarding iris and ciliary body pa-
achieved through extension of the
existing ultrasound biomicroscope
system (Humphrey Instruments).
thology. This method offers an im-
proved assessment of the posterior
surface of the iris and the volume of
Visualisation of posterior iris and cil- the ciliary body. Furthermore, these
A. Kirchhoff ( ) · O. Stachs · R. Guthoff
✉
iary body pathologies in three pa-
tients was performed with a three-
dimensional reconstruction tech-
nique of B-scans. Results: The ex-
tended ultrasound system provided
three-dimensional visualisation of al-
data can be useful for procedures in
computer simulation and calculation
for a better understanding of the
function of the ciliary body in the ac-
commodation process.
Universitätsaugenklinik Rostock,
Doberaner Strasse 140, 18057 Rostock,
Germany
e-mail:
alexander.kirchhoff@med.uni-rostock.de
Tel.: +49-381-4948501
Fax: +49-381-4948502
attenuation by intervening tissue can be minimised by
application of a fluid-coupling medium between eye and
transducer.
Three-dimensional UBM was first described by Cole-
man et al. [3]. In this study we developed a new method
of 3 D UBM and the clinical benefit of this method was
demonstrated in a choice of clinical cases.
Introduction
Ultrasound is the most widely used non-optical diagnos-
tic tool for the imaging of the eye. Pavlin firstly de-
scribed high-resolution ultrasound biomicroscopy
(UBM) in 1990. The authors’ results of a series of clini-
cal cases have shown that this method can provide infor-
mation unavailable with any other imaging technique.
Thus, clinical UBM proved to be a tool with a significant
potential in diagnoses of ocular diseases [7].
Patients and methods
Three patients of the University Eye Clinic Rostock were exam-
ined with the high-frequency UBM. One patient suffered from
contusio bulbi, while the other two had iris tumours. The equip-
ment and technique of the UBM have been described in detail
elsewhere [4, 6, 7]. A 50-MHz transducer that achieves a resolu-
tion of approximately 50 µm was used. The field of view on
screen is limited to 5×5 mm on the commercially available
Humphrey unit. Eyecup immersion scanning was performed with
a frame rate of 8 Hz.
The ultrasound biomicroscope (UBM) provides high
resolution and two-dimensional imaging of the anterior
segment. It has been used in investigations of anatomic
correlations of a variety of disorders, including anterior
segment tumours, cysts, plateau iris, malignant glaucoma
and pigment dispersion syndrome [1, 2, 5, 8, 9, 10, 11,
12]. The use of high-frequency transducers of ca.
50 MHz enabled high-resolution imaging of the anterior
Scanning was performed under topical anaesthesia with the pa-
eye segment. This eye segment is a special case where tient in supine position. An eyecup filled with methylcellulose and

969
saline solution was inserted between the eyelids. Using a standard
B-mode, the transducer was positioned at the centre of the ocular
segment concerned. For 3D imaging, the computer-controlled
scanning system moved the transducer at 90 deg to the plane of
the 8-Hz sector motion (xy-plane) over the eye (z-direction). For
this motion, a miniature skid was mounted on the 8-Hz scanning
device. The technical arrangement of the US probe is depicted in
Fig. 1.
The speed and distance adjustments of the z-motion are vari-
able. The video display of the ultrasound unit was digitised with
8 Hz using a framegrabber board (Hasotec Fg30) synchronised
with the motion control system. The acquisition time for a 3D se-
quence varied between 5 s and10 s; the latter should be the maxi-
mum time, considering movement by the patient and the examiner.
The motion control and data acquisition system was connected
with a SGI workstation via a local area network for 3D reconstruc-
tion using VoxelView (Vital Images, Fairfield, Iowa, USA). This
commercial volume-rendering software package provides an inter-
active environment allowing features such as volume orientation
for viewing planes and 3D perspectives, segmentation and deter-
mination of distances and surfaces. To process one 3D data set a
time of 30 min is necessary. The model-building feature allows the
outline of anatomic structures in space and can additionally be
used for volume measurements.
Fig. 1 The extended ultrasound biomicroscopy system – technical
arrangement of the US probe
Case reports
Case 1
A 42-year-old woman with contusio bulbi was referred to the eye
hospital. Physical examination revealed fine scratches on the cor-
neal surface and a hyphema 1.5 mm high. Furthermore, a lesion of
the iris sphincter and a prolapse of the vitreous body into the ante-
rior chamber of the eye were observed. With the aid of 3D UBM,
a sharply marginated defect of the zonules of Zinn leading to the
prolapse of the vitreous body could be detected (Fig. 2). We de-
fined these zonules as the structures between the ciliary body and
the equator of the lens. Figure 3 shows the clinical situation after
the resorption of the hyphema.
Case 2
A 27-year-old woman had a pigmented iris tumour at the base of
the iris without contact to the corneal endothelium. 3D UBM was
used to demonstrate tumour size and shape. These 3D images are
useful in the long-term follow-up to determine increases in tumour
volume and extent of tissue involvement. Figure 4 shows the clini-
cal appearance, and Fig. 5 shows the 3D images in two slices in a
variety of different planes.
Fig. 2 3D-reconstructed volume of the iris sphincter defect, zonu-
lolysis and prolapse of the vitreous body after contusio bulbi after
3D UBM
Fig. 3 Clinical pictures of a
patient with contusio bulbi and
traumatic iris sphincter defect
and prolapse of the vitreous
body

970
Fig. 4 Clinical pictures of an
prominent iris naevus without
retrocorneal contact
Fig. 5 3D-reconstructed vol-
ume of the iris naevus in 3D
UBM and two different planes
of the digitalised volume
Fig. 6 A view into the volume
of cysts of the iris and ciliary
body in 3D UBM and the clini-
cal picture
Case 3
Discussion
A 35-year-old woman had a non-pigmented iris tumour at the base
of the iris, in contact with the corneal endothelium. The finding
was positive on transillumination. Therefore, the patient was sus-
pected to have iris cysts. Using UBM, one large cyst could be
demonstrated in the conspicuous area. Moreover, multiple small
cysts were detected in the region of the iris and the ciliary body.
Three-dimensional reconstruction, as shown in Fig. 6, revealed a
precise visualisation of the cysts and their topographic relations
that made it possible to document these findings exactly.
This report describes techniques we developed for non-
invasive characterisation of tissue microstructures by us-
ing high-frequency ultrasound, three-dimensional scan-
ning and image reconstruction.
High-frequency ultrasound provides an axial resolu-
tion of approximately 50 µm and a lateral resolution of
less than 100 µm in the focal plane. Through the design
of a miniature skid we added the ability to acquire multi-

971
ple and parallel aligned slice images. The 2D sequential, size, extension and site of the existing pathology. Fur-
parallel sections were reconstructed into three-dimen- thermore, the expanded ultrasound system offers a non-
sional voxel images.
invasive means of obtaining data on the ciliary body re-
We demonstrated this improved method in three dif- gion in three dimensions at high resolution. The three-di-
ferent circumstances: zonulolysis after contusio bulbi, an mensional UBM system is a useful diagnostic tool that
iris tumour and iris–ciliary body cysts. In all cases, the also allows volume measurement, distance spacing in
demonstration with 3D UBM of defects in deeper re- volume and two-dimensional images in any plane of 3D
gions of the eye was successfully performed. Regular volumes. The method improves diagnosis, monitoring
monitoring of the bulb tension was recommended in case and treatment planning. Furthermore, the reported data
1, and repeat 3D UBM every 6 months in case 2 and should be an useful tool for procedures in computer sim-
case 3.
ulation and calculation to achieve a better understanding
We conclude that 3D UBM of the anterior eye seg- of the function of the ciliary body in the accommodation
ment provides clinically useful information regarding process.
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