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Scholarly Journal of Medicine, Vol. 2(4) pp. 51-56 June, 2012
Available online at http:// www.scholarly-journals.com/SJM
ISSN 2276-7134 ©2012 Scholarly-Journals
Full Length Research Paper
Estimating proptosis by digitalized exophthalmometry
in children and teenagers with thyroid diseases
Jurate Jankauskiene and Dalia Jarusaitiene
Eye Clinic, Medical Academy, Lithuanian University of Health Sciences
Accepted 31 May, 2012
Objective of the present study was to construct a device for digital Hertel measurement of eye
protrusion, to use it in practice and measure proptosis in children and teenagers with thyroid diseases.
There was developed the system for the measurement of eye protrusion using Hertel
exophthalmometer, video camera and personal computer (PC). Measurements of proptosis were done in
children and teenagers with thyroid diseases. The difference between the right and left eyes was not
significant. Proptosis in patients was significantly higher than in control group. Digitalization of eye
bulging measurements is important for accurate assessment of proptosis, to compare results of
measurements and to monitor progress of the disease.
Key words: exophthalmometry - thyroid diseases - proptosis.
INTRODUCTION
In people with thyroid diseases may occur Graves’
ophthalmopathy and ocular signs in any age but Graves’
ophthalmopathy are most frequently in the third to fifth
decades of life. Ophthalmopathy may cause diplopia,
decreased
ocular
motility,
exposure
keratitis,
compressive optic neuropathy. Severe ophthalmopathy
develops in men. Severe ocular signs (vision-threatening
exposure corneal, optic nerve problems) require surgical
decompression.
Orbit is an osseous pyramid which contains orbital soft
micro tissues and the eyeball. Due to the increased
volume or orbital contents the retro bulbar pressure rises
and pushing the globe forward causing proptosis.
Exophthalmos is abnormal protrusion of the eye ball and
may be a sign of many severe orbital diseases such as
orbital tumor,
thyroid
eye
disease
(Graves’
ophthalmopathy), orbital varix, arteriovenous fistula,
collagen vascular disease, infections, inflammations,
pseudo tumor, prolapse of cranial contents into the orbit
and congenital cranial - orbital defects, spheroidal
meningioma, lymphoma. Exophthalmometry measures
the relationship between the orbital rim and the anterior
cornea surface (Tsai et al., 2006). Exophthalmometry, the
Corresponding author e-mail: [email protected]
quantitative assessment of the position of the globe in the
orbit, is a clinically useful measurement and has become
a routine examination for any patients with suspected
orbital disease, especially is important in thyroid eye
disease or Graves’ ophthalmopathy because proptosis
may be main sign in these diseases (Stan et al., 2012).
The orbital involvement in Graves’ disease is
characterized by lymphocytic infiltration and edema of the
retro bulbar tissues, resulting in marked swelling of
extraocular muscles and orbital fat. Normal value of
ocular protrusion is different in various nations and is very
important to differentiate from pathological proptosis
levels. GE Krassas (2007) showed that normal values
depend on type of exophthalmometer, age and gender.
Traditionally, in the absence of other clinical signs, orbital
pathology
of
one
eye
is
suspected
when
exophthalmometric values are outside of the normal
range or when there is more than 2 mm difference
between the eyes. Autoimmune hyperthyroidism is the
most common cause of juvenile thyrotoxicosis in children
and teenagers. Eha et al. (2010) revealed that in children
and teens Graves’ ophthalmopathy is less common than
in adults. Chan et al. (2002), Durairaj et al. (2006),
Krassas (2004, 2005) showed that eye clinical picture in
children is less well defined than in adults.
Normal values of proptosis for children under the age of
11 years were reported by Nucci et al. (1989).
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Jankauskiene and Jarusaitiene
52
Proptosis values were very variable. Wong and Cheng
(2001) revealed that Graves’ disease in childhood is
increased. Shibayama et al. (2005) showed increase of
thyroid-stimulating antibodies and thyrotropin-binding
inhibitory immunoglobulin in children with Graves’
disease.
Exophthalmometry measurements of childhood Graves’
ophthalmopathy tend to increase with age (Gerber et al.
(1972). Sleep and Manners (2002) noted that variation of
the readings of Hertel exophthalmometer was seen
between instruments from different manufacturers. Hertel
exophthalmometry difficulty is mainly caused by the low
sensitivity and reproducibility. There are some digitalized
techniques to measure eyelid positions, photographic
measurements in patients (Rubin (2005), Edwards et al.
2004). No such information about digitalization of
exophthalmometer is available in the literature. Objective
of the present study was to construct a device for digital
Hertel measurement of eye protrusion and measure
proptosis in children and young adults with thyroid
diseases.
MATERIALS AND METHODS
Hertel exophthalmometer was used to measure the
eyeball protrusion out of the orbit (eye’s level of
proptosis) to determine its position along the sagittal axis.
Doctor sits opposite the examined person at ocular level
during the evaluation. The doctor asks the examined
person to look straight ahead, to keep the head still and
wide open eyelids aperture. The mirrors of the
exophthalmometer with millimeter scales for the left and
right measuring halves are calibrated so that the zero
mark on the scale is located in the plane of the resting
points of exophthalmometer rims. In order to measure
proptosis the resting points of exophthalmometer are
placed against the temporal orbital rims. The corneal
axes are reproduced on the mirrors; the mirror images
appear at equal distance behind the mirrors and therefore
fall on the rulers. Apparatus is constructed so that the eye
axes coincide with the ruler in eye axis. The instrument is
maneuvered using both hands and firmly propped first
against the right-hand orbital wall on the temporal side.
Apparatus which measures from the lateral orbital rim
has an unavoidable error: the greater the pressure over
the lateral orbital rim and the longer this pressure is
maintained, the more the soft tissues over the lateral
orbital rim are compressed. An error of 0.5 to 1.0 mm can
easily be produced by long pressure.
In order to investigate the exact proptosis, examiner
should be able to determine accurately the relative
position of the two orbits in the skull, the frontal plane of
the skull, the relative positions of the two lateral orbital
rims, the measurements of the length, width, height,
capacity of each orbit, an axis through the lateral orbital
rim vertical to the frontal plane (which axis is, after all, a
function of the frontal plane). Such an axis would be
parallel to the visual line with "eyes front."
These measurements are determined not accurately
and data of exophthalmometry are not enough right.
Measurement error can be reduced by increasing stability
and reducing the human factor, in determining the
parallelism of the distances.
We propose the use of simple and non-invasive digital
image
analysis
to
estimate
exophthalmometric
parameters of children and young people with thyroid
diseases. It was decided to increase the stability of the
system with Hertel exophthalmometer consolidation into
metal structure. Digital video camera was added to this
construction (figure 1), this allowed to see the results of
measurements of the Personal Computer (PC) screen
and save them in digital form. Digitalized measurement
system includes:
a) Hertel exophthalmometer;
b) Horizontal floating part of the device for consolidation
of video camera and selection of position in order to
photograph the results of Hertel exophthalmometer of the
left and right eyes;
c) Regulated part of the device for patient's face
consolidation and for fixation of position of Hertel
exophthalmometer.
d) Video camera and personal computer.
Experiments
Experiments were done with web camera CNRWCAM820. This is 2.0 Mega pixel high quality tube style
USB webcam. It features a five-layer glass lens with a
viewing angle of 70 degrees, face tracking software, a
digital zoom function and an automatic brightness
adjustment, white balance and color compensation. It can
be positioned stably on a flat surface. The CNRWCAM820 is compatible with all Windows versions
available. Images saved as JPEG files.
The camera and Hertel exophthalmometer were
positioned at eye-height. Measurements were taken in a
well illuminated room, with subjects seated in an upright
position with the head erect. Subjects were asked to look
at a distance fixation target, framing the face centrally,
using a video camera (figure 2). The reading was taken
as the distance between a point on the temporal orbital
rim, the deepest palpable point on the angle, and the
apex of the cornea. Both the right eye and left eye
readings were taken sequentially without removing the
instrument from the orbital rims. Measurements for the
right and left eyes were averaged for each subject and
measured in millimeters (mm).
Video camera through the USB connector connects to
the personal computer. At the display of computer are
visible mirror of Hertel exophthalmometer with the ruler
and lateral view of the patient’s eyeball. Using the Web
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Scholarly J. Med.
53
Figure 1. The device for measurement of proptosis
Figure 2. Quantification of eye bulging (proptosis) using Hertel exophthalmometer and video camera
Camera photographing function, the image can be saved
in 1600 * 1200 resolution JPEG / BMP file format. The
distance between the lateral orbital walls can then be
read from the upper side of the scale at the display of
personal computer; this distance can be noted for future
reference (figure 3).
The examiner measures proptosis in each eye by
looking into the mirror (which has a millimeter scale
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Jankauskiene and Jarusaitiene
54
Figure 3. An example of digitalized result of proptosis measurement
marked on it) with one eye and moving the head
horizontally. The examiner can determine the position of
the corneal apex of the patient from the millimeter
reading and compare the resulting measurements to
normal values in order to determine if further testing or
treatment is needed. Physiologically, there are also
certain differences in the degree of proptosis in each eye.
For basic measurement in this construction the distance
between the lateral orbital rim and corneal apex axis was
measured. Under normal conditions, the distance
between the apex of the cornea and the orbital wall is
approximately 17 mm. This value should only be
regarded as a statistical average, from which there may
well be upward or downward deviations.
Image analysis is the extraction of meaningful
information from images; mainly from digital images by
means of digital image processing. Because proptosis
causes clinically perceived distortions in orbital
architecture, digital photographs can also be used to
detect and quantify these changes in eyeball protrusion
measurements.
Noninvasive
standardized
digital
exophthalmometry allows reliable ocular documentation
and clinical assessment in thyroid diseases or orbital
pathology, with regard to orbital changes. Saving of the
results provides new opportunities: to collect
measurements for each patient, perform image analysis,
compare results of measurements and monitor progress
of the disease, dynamics of the changes after the
treatment. The system gives us reproducibility and
repeatability of the results.
Proptosis was measured in 45 children and teenagers
with thyroid diseases and 39 persons of the control
group.
Statistical analysis
Statistical analysis was conducted using statistical SPSS
software package (Version 16.0). The following statistical
characteristics were expressed as a mean value and
standard deviation (SD). The statistical difference
between patients and control groups was tested with the
Student’s t-test. For groups with abnormal distribution
Mann-Whitney U test for independent samples was used.
A p value less than 0.05 was considered statistically
significant.
RESULTS
Mean age of patients was 10.60±3.77 years, range from
4.5 to 18 year, there were 40 girls and 5 boys. Mean age
of persons of the control group was 10.83±4.46 years,
range from 5 to 18 year. The measurements included
exophthalmometry of the right and left eyes. No individual
had greater than 1 mm difference between eyes.
Table 1 shows the mean (± standard deviation)
measurement of the right eye was 17.89 ± 1.77 mm,
ranging from 15.5 to 22.0 mm. Exophthalmometric values
for patients had a mean of the left eye was 17.73±1,
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Scholarly J. Med.
55
Table 1: The mean (±SD) of exophthalmometry in children and teenagers with
thyroid diseases
Subjects
Patients Mean+SD(mm)
Control group Mean+SD(mm)
P value
Right eye
17.89 ± 1.77
14.54 ± 1.34
0.001
64 mm and ranged from 15 to 21.5 mm. The difference
on exophthalmometry between the right and left eyes
was not significant (Table 1). Mean of proptosis in
patients was significantly higher (p<0.001) than in control
group (right eye mean was 14.54±1.34 mm, ranging from
12.5 to 16 mm), (left eye mean – 14.42±1.20 mm,
ranging from 13 to 16.5).
DISCUSSION
There are some methods for interpretation the
exophthalmometric
readings:
absolute
exophthalmometry, relative exophthalmometry and
comparative exophthalmometry (Comer, 1991). Absolute
exophthalmometry is method when we compare
exophthalmometric levels to known normal level of
exophthalmometry. Relative exophthalmometric data are
the data of the comparing of the right and left eyes
exophthalmometry
measurements.
Comparative
exophthalmometry is comparing exophthalmometric
values with time. There are some factors which influence
exophthalmometric readings: the doctor uses not the
same exophthalmometer at the time, different designs of
exophthalmometers. Using the Hertel exophthalmometry
we may compare the unilateral and simultaneous bilateral
measurement of the globe position (Ameri and Fenton,
2004). According to the configuration of the osseous orbit
and various nations, races, a value of 14 mm might be
pathological whereas 20 mm might be normal.
Exophthalmometric data may vary according to age,
gender, height, weight, body mass index, ethnicity orbital
parameters and refraction (Beden et al., 2008, Kashkouli
et al., 2003, Smolders et al., 2004). Continuous
screenings
are
more
useful
than
individual
measurements. Mourits MP et al. (2004) showed that
there was no dependence on age in healthy individuals
and in Graves' patients’ adults. Measurements depended
on sex (in males were bigger measurements).
Fledelius and Stubgaard (1986) revealed that eye
position changes during growth and adult life and
exophthalmometry,
interpupillary
distance,
orbital
distance measurements may vary. Image Processing
with Image J was used in biomedical and clinical practice
(Abramoff et al. 2004). New magnetic resonance imaging
methods are used in diagnosis and differential diagnosis
of Graves’ ophthalmopathy and other orbital diseases
(Roshdy et al., 2010). FruehandFrueh (2007)
Left eye
17.73 ± 1,64
14,42 ± 1.20
0.001
P value
0.33
0.09
performed an analysis of Hertel exophthalmometer
Geometry and revealed that exophthalmometers should
be used with the narrowest feasible base and the
examiner should be consistently positioned as far from
the reflecting surface of the instrument as possible.
Chang et al. (1995) compared results between the Hertel
and Luedde instruments. There was no statistically or
clinically significant difference between measurements
taken with the Luedde as compared with the Hertel
instrument. The Luedde exophthalmometer has a number
of advantages over the Hertel exophthalmometer, and
represents a simple, inexpensive and equally reliable
means of evaluating clinically the anteroposterior position
of the eye in the orbit.
Sleepand Manners (2002) showed variability in
exophthalmometry measurements taken with different
manufacturers of exophthalmometers. This study
suggested that the same instrument should be used for
each examination to minimize error caused by variation
between instruments. It is useful for measurements in
dynamics of the conservative and surgical treatment of
patients. We have found quite marked proptosis in
children and teenagers with thyroid diseases in
comparison with control group. Our data correspond with
findings of other authors. Liu et al. (1996) and Uretsky et
al. (1980) found persisting proptosis in children.
The exophthalmometric values we obtained can either
serve as a diagnostic guide or be used to monitor
progress of orbital disease via serial measurements. A
larger image at the display, the possibility to calculate
data, close to the routine measurement, more accurate,
we get digital image, set up a data base of personal
measure and document proptosis, monitor the dynamics
of measurements, acceptable for medical and scientific
tasks. Serial proptosis exams are required to monitor
disease
progress
and
response
to
therapy.
Computational image editors can display and analyze
digital images, and digital image pixels can be quantified
and measured. These properties allow the use of digital
image analysis systems to estimate external ocular
modifications, several differences between controls and
patients with orbit diseases that can be observed with
digital image.
Practitioners may also need to know exophthalmometry
measurements.
The
effective
measurement
of
exophthalmometric parameters could lead to an objective
estimation of the effects of therapeutic interventions. It is
a more sensitive way than Hertel exophthalmometer
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Jankauskiene and Jarusaitiene
56
itself. When performing clinical or experimental trials, the
increase in sample size, the number of pictures per eye,
or even the use of a video camera for selecting the more
representative picture can reduce any interference with
accurate measurements. Careful standardization of light,
framing, zoom and position remains the key factor for
accurate orbital measurements. Availability, noninvasiveness, ability to transfer and display make digital
exophthalmometry a suitable method for clinical
documentation and clinical trials and scientific
investigations.
Digital photographs can also be easily stored and reemployed in future studies. Digital exophthalmometry can
be used to objectively estimate exophthalmometric
parameters for patients with thyroid diseases in clinical
practice. Examples of image analysis techniques in
different fields include: 2D and 3D object recognition,
image segmentation. This will further work in this
direction.
CONCLUSIONS
A new method for the measurement of eye protrusion
using Hertel exophthalmometer, video camera and PC
has been studied and tested. It would lend itself to
accurate and convenient use in clinical practice.
Measurements of proptosis were recorded in children and
teenagers with thyroid diseases. The difference between
the right and left eyes was not significant. Proptosis
measurements in patients was significantly higher
(p=0.001) than in controls. Digitalization of proptosis
measurements is suitable method for clinical
documentation, monitoring disease progression and
status of exophthalmos after the conservative and
surgical treatment, it may take part in clinical trials and
scientific investigations.
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