Five in One: An Innovation That Combines
Several Diagnostic Strategies
Pentacam – The World’s First 3 D-Scheimpflug Camera
F
or any ophthalmologist who
considers buying a new device
for his private surgery or clinic, the
cost-benefit ratio of such an investment is of primary importance.
Besides asking “What is this
instrument able to do what others
can’t” there is – for most doctors –
the space issue: “Do I have room
for another unit?”. It is a compact
instrument which combines several
diagnostic strategies and promises
to fulfill the highest clinical, as
well as practical demands, and to
fit in a very restrictive budget.
A symposium at the 17th Congress
of Germany’s ophthalmic surgeons
in Nuremberg left the audience with
the impression that such a device
is now available: the Pentacam,
the world’s first three-dimensional
rotating Scheimpflug camera. This
most intriguing innovation was presented by experts like O. Kermani
(Cologne), T. Neuhann (Munich)
and O. Schneider (Wetzlar).
The most striking feature of the
Pentacam is that it is much more
modules which analyze and interpret the tasks performed: Scheimpflug picture, pachymetry, densitometry, corneal topography, 3-D
chamber analysis and tomography.
The data acquired is extremely
useful for a number of ophthalmological indications: refractive surgery, glaucoma, cataract and pathological conditions of the cornea like
keratoconus.
Oculus Pentacam: Complete diagnosis
of the anterior ocular segments
than just a camera. It is a diagnostic
unit able to perform a host of different measurements and analyses
on the anterior segment of the eye.
Using an automatic rotating camera,
this innovation examines the anterior segment without ever touching
the eye. The examination takes
approximately two seconds, time
enough to take about 50 pictures
of the eye’s different anatomical
layers. There are several different
3-D analysis of the anterior
chamber helps to assess
the risk of glaucoma
Scheimpflug pictures can be taken
as a series of single exposures from
different angles as well as a 3-D
scan. The 3-D analysis presents the
different layers (anterior corneal
segment, the cornea’s posterior
layer, iris and lens) in an easily
recognizable way. In addition, the
Pentacam automatically measures
the anterior chamber angle, chamber volume, chamber depth, cor-
Pentacam
neal eccentricity, pupillary diameter, the cornea’s central radius and
corneal astigmatism at the same
time. Pictures taken as a 3-D
scan can be analyzed individually.
According to O. Kermani, there is
no significant difference between
Pentacam´s pachymetric results and
those of comparable (though exclusively pachymetric) instruments
already on the market. The same
applies if the Pentacam’s keratometry is compared to that of devices
already in use. An additional, and
sometimes crucial benefit is measuring the anterior chamber depth.
This gives the ophthalmologist a
realistic idea of how seriously his
patient may be threatened by
glaucoma. That knowledge can be
decisive in the preoperative planning of corneal or lens surgery
which might lead to a (further)
shallowing of the chamber. T.
Neuhann made it quite clear if the
surgeon has to deal with a chamber
depth of less than 2 millimeters, a
prophylactic YAG iridotomy should
be performed as an efficient way
to prevent angle closure.
Measuring the cornea’s
thickness helps to evaluate
the “true” IOP
Glaucoma is in the literal crosshairs
of another examination, measurement of the corneal thickness,
which in some European countries
like Germany has gained wide
acceptance among the population.
It is known that measuring the
intraocular pressure (IOP) using a
Goldmann is not the only test in
glaucoma diagnostics. Intra-ocular
pressure alone is only one of several
factors that determine the existence
of glaucoma. This decision requires
a careful examination of the optic
disc. But the IOP measured by
tonometry might not be exactly
the pressure that actually exists
The cornea’s thickness is displayed for the whole surface
from limbus to limbus.
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inside the eye. The reason for this
confusion, corneal thickness influences the results of tonometry to
a sometimes significant degree.
If the patient’s cornea matches
exactly the statistically “normal”
thickness of 550 µm, the IOP measured is indeed the IOP that keeps
the eye in shape or, in glaucoma,
threatens to damage the neuronal
axons. If the cornea is thinner,
however, it is easier for Goldmann’s
device to flatten its surface – the
result is an IOP reading which
is unrealistically low. A result
might give both the doctor and his
or her patient an undue sense of
security – the threat of glaucoma
hides behind a false interpretation
of Goldmann’s tonometry. The
opposite can happen with a cornea
of above-normal thickness: an
“increased” IOP will be measured
which might lead to glaucoma
therapy that – given the real, lower
IOP – comes too early or is too intense.
How Pentacam portrays a case of cataracta coronaria.
OPHTHALMO-CHIRURGIE SPECIAL EDITION NOVEMBER 2004
Pentacam
Using Pentacam’s pachymetric
abilities puts these data into its
proper place again. If the ophthalmologist knows the exact corneal
thickness, calculating the real IOP
with some formulas is no problem
at all. One of these formulas to
determine the IOP, after having
measured corneal thickness, has
been developed by Professor Lutz
Pillunat and his team at the University Eye Hospital in Dresden.
Using it on patients with an extremely thin or an extremely thick
cornea gives you an idea of how
misleading tonometry can become.
A cornea that is only 450 µm thick
may have an IOP that is no less
than 4,0 mm below the real thing
– and in daily ophthalmological
practice, it makes a difference
whether a patient’s intra-ocular
pressure is 20 mm Hg or 24 mm
Hg. A difference like this may
be important to decide between
initiating treatment and a waitand-see attitude. In dealing with a
thick cornea, the IOP has to be
adjusted to a lower value. If, for
example, the Pentacam detects a
corneal thickness of 630 µm in a
patient, according to the Dresden
formula 3,20 mm Hg has to be taken
away from the IOP measured with
Goldmann’s tonometry.
Refractive surgery without
knowing corneal thickness?
Never !
Pachymetry provided by Pentacam
not only plays a major role in glaucoma diagnostics, but also in the
pre- and postoperative care of
patients undergoing refractive sur-
gery T. Neuhann has pointed out –
to know the exact location of the
cornea’s thinnest spot. The Pentacam’s keratometry gives the ophthalmic surgeon an excellent overview of the patient’s corneal topography and puts him or her in a
position to operate even in areas
with a relatively thin stroma while
keeping the necessary safety distance. A postoperative assessment
of the flap is easily done and
doesn’t bother the patient at all.
The most important features of this
examination are
• automatic initiation of the measurement,
• a high reproducibility,
• non-contact measuring,
• less than two seconds required.
Pentacam’s pachymetry provides
data from one limbus to the other.
Densitometry of the lens:
a great tool for the long-term
control of cataracts
The cataract surgeon enjoys the
same benefits by relying on a preoperative scan done with Pentacam.
Pentacam’s densitometry of the
human lens provides the ophthalmologist with an analysis of the
lens thickness and of structural
alterations like radial opacities
and early or advanced calcification
of the lens core. Densitometry comes
with advantages:
• the evolution of a cataract can be
made visible even at an early
stage,
• it makes classification of the cataract easy,
• long-term controls of cataracts
are possible and
OPHTHALMO-CHIRURGIE SPECIAL EDITION NOVEMBER 2004
• the extension of the cataract can
be measured.
Knowing the thickness of the lens is
helpful for the ophthalmic surgeon
in deciding which type of IOL
(intra ocular lens) to use for implantation. Furthermore, it hints –
together with data on the anterior
chamber’s depth – to possible causes
for postoperative trouble. Hyperopic eyes which are relatively
short sometimes are a major cause
for concern. In the event of angle
reduction they tend to react with a
postoperative IOP increase. They
also have a higher risk to develop
a macular degeneration following
phacoemulsification (or to worsen
if macular degeneration already
exists at the time of cataract
surgery). Assessing the anterior
chamber’s depth map is also possible when using Artisan intraocular lenses, a task that, according to O. Kermani, both OrbScan
II and IOL-Master can not perform.
Examination by Pentacam is
both efficient and fast...
Using Pentacam in your daily surgery is both easy and time-saving.
According to O. Schneider the instrument takes about 50 Scheimpflug pictures within just two seconds and can deliver up to 25.000
true elevation points of topographical information when measuring corneal topography. Due to
the high amount of data collected
there usually is enough information
to come to a reasonable diagnosis.
Even situations traditionally considered artifacts like a narrow lid
margin or shadow zones can’t
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Pentacam
prevent the Pentacam from producing sufficient Scheimpflug pictures for clinical assessment
...and makes it easy
for the patient to see his
doctor again
An examination is absolutely
pain-free and is done within the
shortest time span it’s most likely
to become a favorite with the
patients and thus strengthens the
patient-doctor relationship. Everything with Pentacam happens in a
non-contact way which reassures
even the most timid patient. It is
also an educational tool because a
printout of his or her own clinical
picture as captured by Pentacam
can be handed over to the patient.
It is quite an impressive document.
T. Neuhann compares its psychological impact on the patient with
the sonographic picture of a baby
in utero that usually is a source of
joy to any expecting mother (and
father).The price for such an extensive clinical examination currently is about 75 Euro. The fact
that operating Pentacam can be
delegated to the practice’s person-
Cataracta pulverulenta, as seen by Pentacam.
OPHTHALMO-CHIRURGIESpecial Edition in collaboration
with Oculus Optikgeräte GmbH,
Münchholzhäuser Straße 29,
35582 Wetzlar, Germany
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nel also contributes to its economic
efficiency. Analyzing the results
and discussing them with the
patient should be done only by the
ophthalmologist. Neuhann’s conclusion: the Pentacam is a diagnostic
tool which helps all ophthalmologists. With its ability to focus on
several aspects like diagnosing
glaucoma, preparing for cataract
surgery, the pre-operative planning
and follow-up of refractive surgery
and the evaluation of keratoconus
it enables the ophthalmologist to
get an excellent overview of everything that matters in the anterior
segment of the eye.
3 D Tomography of the eyes’ anterior segment.
Editor:
KIM – Kommunikation in der Medizin
Author: Dr. med. Ronald D. Gerste
Project manager: Dr. med. S. Kaden
Dr. R. Kaden Verlag GmbH & Co. KG
Ringstraße 19b
69115 Heidelberg
Germany
OPHTHALMO-CHIRURGIE SPECIAL EDITION NOVEMBER 2004