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CONTACT VERSUS NONCONTACT WIDE-FIELD VIEWING SYSTEMS: Why Not Have the Best of Both Worlds?

Authors:
New Instruments
CONTACT VERSUS NONCONTACT WIDE-
FIELD VIEWING SYSTEMS
Why Not Have the Best of Both Worlds?
Carlos Mateo, MD
Anniken Burés-Jelstrup, MD
From the Vitreoretinal Surgery Department, Instituto
de Microcirugía Ocular, Barcelona, Spain.
Until the development of wide-angle visualization
systems (WAVs), perioperative viewing of the central
and peripheral retina was performed by direct vision
using precorneal lenses, which enabled working on
only one specic area at a time. With this approach,
proper vision is hindered in eyes with small pupils or
corneal opacities and during air exchange, particularly
in phakic eyes.
Current WAVs are divided into two main types:
contact and noncontact systems. Both provide an
inverted image that must be reinverted to allow correct
visualization for the surgeon. Spitznas et al were the
rst to report the use of a stereodiagonal inverter to
achieve a properly oriented view.
1,2
In 1989, Avi Grinblat developed a panoramic
system based on binocular indirect biomicroscopy,
and in 1992, Chang described the contact wide-eld
viewing system at the Wacker Prize lecture of the Club
Jules Gonin.
With contact systems, the wide-angle lens is
placed directly on the cornea, which has been
previously coated with viscoelastic polymer. The
size of the eld of view varies depending on the
optical properties of the lens. The lens can be used
with any microscope equipped with an image
inverter, and it provides excellent visualization by
reducing reection from the corneal surface and
avoiding inherent corneal aberrations and those
related to ocular movement produced during manip-
ulation of the instruments through the sclerotomies.
Despite these excellent qualities, this system is not
the most widely used in vitreoretinal surgery because
of three essential factors. First, it requires the help of
a highly trained assistant who spends most of the
time manually positioning the lens to obtain the best
possible visualization. Second, the microscope-
viewing head must run a lengthy distance between
the position needed for working on the macula (low
position) and a position for working on a much larger
eld. This may exceed the total possible movement
range of the head, and a second assistant is needed to
manually adjust the height, with the consequent loss
of time. Last, in complex cases requiring bimanual
surgery, the operative eld can become very
crowded,including the assistants hands position-
ing the wide-angle lens, the surgeonshands,and
sometimes the hands of a second assistant to position
the chandelier light for best possible illumination/
visualization.
As the name implies, with noncontact systems, the
wide-angle lens is placed above the corneal surface,
but there is no direct contact. The main advantages of
this approach are that there is no need for an assistant
to hold the lens in position, the eye can be rotated, and
the size of the eld of view can be changed by varying
the distance from the lens to the cornea. However,
there is a drawback: As the lens approaches the cornea,
condensation can develop on the undersurface of the
lens. In addition, corneal desiccation must be avoided
by constantly applying viscoelastic material. Several
measures have been described to manage these
difculties.
3
In some situations, better visualization is obtained
with noncontact than contact systems, especially in
eyes with small pupils or over certain surfaces (e.g.,
osteo-odonto-keratoprostheses, Boston keratoprosthe-
ses, or temporary keratoprostheses). In other situa-
tions, however, contact systems provide higher quality
vision and a larger eld of view during surgery.
Hence, it could be useful to device a way to enable
the use of both these WAV options on the same
instrument, depending on the requirements of each
individual case. To our knowledge, there is only one
None of the authors has any nancial/conicting interests to
disclose.
Reprint requests: Carlos Mateo, MD, Instituto de Microcirugía
Ocular, C. Josep Maria LLadó 3, 08035 Barcelona, Spain; e-mail:
carlosmateo@me.com
1
Copyright ªby Ophthalmic Communications Society, Inc. Unauthorized reproduction of this article is prohibited.
previous report describing an approach to use both
types of visualization, but it does not seem to have
gained much popularity.
4
RESIGHT 700 Fundus Viewing System (Carl Zeiss
Meditec AG) is a noncontact WAVs that incorporates
a focusing device (varioscope) between the micro-
scope and the lens that can be implemented manually
or by using a foot pedal. The distance between the
varioscope system and wide-angle lens is xed, and
the lens is attached to a spring-loaded arm that retracts
to avoid corneal lesions if the microscope head is
erroneously moved instead of the varioscope when
attempting to focus. In light of the potential advan-
tages provided by each type of WAV, our aim was to
design a holder for an HRX wide-angle contact lens
for use on RESIGHT 700. This device could enable
both noncontact and contact viewing during surgery
and considerably reduce the need for positioning by an
assistant.
The lens holder was designed with Autodesk Maya
software (Autodesk, Inc, San Rafael, CA) and produced
using 3D printing technology (Shapeways, New York
City, NY). The holder is made of a thermoplastic
material and can be sterilized using steam sterilization
or low-temperature methods (e.g., formaldehyde). The
device can be reused several times after sterilization.
The proximal end of the device is introduced into
the RESIGHT holder, and the wide-eld lens is
inserted in the distal end of the device, maintaining
the lens in complete alignment with the visual axis of
the microscope. When the lens is positioned on the
corneal surface using this holder, focusing is achieved
using the RESIGHT varioscope. If the microscope
head is inadvertently lowered, the RESIGHT retracting
arm will avoid damage to the cornea. This automatic
fold-up system and varioscope focusing are unique to
RESIGHT 700; therefore, to our knowledge, the lens
holder presented here is not adaptable to other non-
contact systems.
Some important considerations should be taken into
account when using our device. The patients head
should be positioned so that the surface of the iris is
parallel to the objective of the microscope to obtain
better performance of the system. Likewise, the tilt of
the microscope head may change the eld of view;
hence, before starting the procedure, it is important
to position the microscope head at 0°, with no tilting
(Figure 1). In addition, a larger amount of viscoelastic
material is needed to avoid air bubble formation
between the lens and the cornea when the lens holder
is used than when an assistant is holding the lens. This
is likely because the assistant produces some pressure
on the cornea, whereas the pressure of the RESIGHT
arm is minimal (0.30.4 N), making it easier for inter-
position of air between the lens and cornea. Finally,
the additional thickness of the holder slightly increases
the total circumference of the wide-angle lens, which
Fig. 1. Lumera 700 microscope head (Carl Zeiss Meditec AG, Jena,
Germany). For proper functioning of the system, the indicator on the
head (*) should be set so that there is no tilting.
Fig. 2. The holder slightly increases the circumference of the pre-
corneal lens, and this may lead to friction with the surgical instruments,
especially in eyes where the instruments are used in a very vertical
position, as in myopic patients.
Fig. 3. Image taken during surgery, showing how the device keeps the
lens completely parallel to and aligned with the focusing lenses of the
microscope.
2RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES 2017 VOLUME 0 NUMBER 0
Copyright ªby Ophthalmic Communications Society, Inc. Unauthorized reproduction of this article is prohibited.
may make it more difcult to work with highly myopic
eyes, in which the instruments must be placed in a very
vertical position. To avoid this problem, it is helpful
to place the cannulas at 4 to 4.5 mm from the limbus
(Figure 2).
In the last 230 cases treated using the device
presented here, there has been no need for the help
of a trained assistant (Figure 3). However, in particu-
larly complex cases, the lens can be easily removed
from the holder for manual positioning, and focusing
can continue with the RESIGHT varioscope.
In summary, here we report the development of
a simple device that can achieve the best possible
visualization during vitrectomy in each individual
case, by enabling contact and noncontact capability
using the same system.
Key words: pars plana vitrectomy, contact wide-
angle visualization systems, noncontact wide-angle
visualization systems.
References
1. Spitznas M, Reiner J. A stereoscopic diagonal inverter (SDI) for
wide-angle vitreous surgery. Graefes Arch Clin Exp Ophthalmol
1987;225:912.
2. Spitznas M. A binocular indirect ophthalmomicroscope (BIOM)
for non-contact wide-angle vitreous surgery. Graefes Arch Clin
Exp Ophthalmol 1987;225:1315.
3. Kreps EO, Lemm JM, Ruagh EA, et al. Fogging of non-contact
viewing lenses during vitreoretinal surgery. Retina 2016;36:
24282429.
4. Murthy RK, Chalam KV. Assistant-independent OptiFlex sys-
tem for contact and noncontact wide-angle viewing in vitreor-
etinal surgery. Arch Ophthalmol 2010;128:490492.
NEW INSTRUMENTS 3
Copyright ªby Ophthalmic Communications Society, Inc. Unauthorized reproduction of this article is prohibited.
Article
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Purpose: To report a sutureless and equipment-free technique for contact lens wide-angle viewing system during vitreoretinal surgery. Methods: A step-by-step procedure and a surgical video using this technique were proposed. Results: This technique needs only 3-finger control of contact lens either by the left hand (for the right-handed surgeon) or right hand (for the left-handed surgeon). The contact lens is not fixed to the environment (lid speculums, cannulas, corneoscleral limbus), therefore it allows the surgeon to move and tilt the contact lens freely while keeping a clear view of the retina. Conclusion: The sutureless and equipment-free technique for contact lens viewing system during vitreoretinal surgery has been tried and tested, and is practical and effective in the real world.
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