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Med. J. Cairo Univ., Vol. 79, No. 2, March: 191-194, 2011
www.medicaljournalofcairouniversity.com
Capsulorhexis Marker: A New Tool for Accurate Sizing and
Centration of Capsulorhexis in Animal Model
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MOHAMED A. HASSABALLA, M.D. , and AMR A. OSMAN, M.D. ,
The Department of Ophthalmology, Faculty of Medicine, Cairo University
El-Noor Eye Hospital 3
Abstract
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, El-Rowad Eye Hospital and
may be discontinuous [3] . Moreover, the introduction of multifocal intraocular lenses (IOLS) increased the need for a better surgical performance
and precision. Many investigators tried to design
new tools for better sizing and shape of the capsulorehxis for example diathermy rhexis [4] andvitrectorhexis [5] .
Purpose: To describe a new instrument (capsulorhexis
marker) to optimize the size, shape, and centration of the
capsulorhexis during phacoemulsification.
Setting: Wet Lab. sponsored by Alcon laboratories.
Methods: 10 goats eyes were prepared for the procedure.
A specially designed capsulorhexis marker with a circular
part having an inner diameter of 5.5mm was used. The lower
edge of the circular part of the marker was stained by viscot
surgical marker and applied to stain the anterior capsule in
well defined circular fashion.
Certain styles of capsule forceps have been
designed with laser marks to help surgeons to
produce various capsulotomy diameters. However,
these forceps are limited in their ability to provide
a diameter reference in the horizontal meridian
parallel to the phacoemulsification incision [6] .
Results: There was no encountered difficulty in introduction or removal of the marker from all eyes. In 8 eyes there
was a well centered rounded mark which was adequately
stained.
The aim of this study was to describe a new
instrument to optimize the size, shape, and centration of the capsulorhexis during phacoemulsification. Up to our knowledge, this is the first published
article in literature describing capsulorhexis marker
staining the anterior capsule.
Conclusions: The capsulorhexis marker is an instrument
designed to help in accurate sizing and to perform a perfectly
centered round capsulorhexis.
Key Words: Capsulorhexis marker – Centration –Animal.
Introduction
Material and Methods
SINCE surgeons transitioned from intracapsular
to extracapsular cataract extraction, a well-constructed capsulotomy has been the key to a successful procedure. Since the phacoemulsification era
began, capsulorhexis has become the standard
capsulotomy technique. Anterior capsulorhexis can
be performed using 26 G bent needle cystitome or
capsulorhexis forceps [1,2] .
This study was performed in a wet Lab. sponsored by Alcon laboratories. The wet lab is fully
equipped with high resolution microscopes, disposable instruments and good video recording. A
capsulorhexis marker was specially designed for
this study. It is made of stainless steel. It is formed
of a handle attached to a circular part having an
inner diameter of 5.5mm and 1mm height (Fig. 1).
10 goat's eyes were prepared for the procedure. In
each eye a 3mm limbal corneal tunnel was performed, and then vesicoelastic material was injected
into the anterior chamber. Afterwards, the wound
was widened to 6mm to allow easy introduction
of the instrument. In 5 eyes, the lower edge of the
circular part of the capsulorhexis marker was
stained by viscot surgical marker pen (gentian
violet dye). In another 5 eyes, the lower edge of
With a free-hand method, it is not easy to create
a perfectly sized anterior capsulorhexis that is also
perfectly centered relative to the pupil or the limbus.
The anterior capsulorhexis obtained is usually
continuous but may be noncurvilinear, varying
from renal to heart shaped and in some cases, it
Correspondence to: Dr. Mohamed A. Hassaballa, 10 Madkour
St., El Haram, Giza, E mail: [email protected]
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Capsulorhexis Marker: A New Tool for Accurate Sizing & Centration
the circular part of the capsulorhexis marker was
stained by viscot surgical marker pad (Vismark,
gentian violet pad, Viscot medical, IIC). This pad
is a useful tool to stain corneal markers during
keratoplasty procedures. The capsulorhexis marker
was introduced into the anterior chamber (Fig. 2)
and applied to the anterior capsule for few seconds
without pressure to avoid zonular stress. Special
care for centration of the capsulorhexis marker in
relation to the pupil was done. The marker was
then removed from the eye and assessment of the
mark was done as regards centration and degree
of staining of the anterior capsule (Fig. 3).
Results
There was no encountered difficulty in introduction or removal of the marker from all eyes. In
all cases, the lower edge of the circular part of the
capsulorhexis marker was adequately stained. There
was no significant difference in the degree of
capsular staining by using either the viscoat marker
pen or marker pad. In the first two eyes, the mark
was not clear due to sliding of the marker on the
surface of the anterior capsule; this resulted in
spread of the stain leading to a diffuse mark on
the surface. In all other cases, special attention
was done so as not to slide the marker on the
surface of the anterior capsule with precise marking
technique to avoid this complication. This resulted
in well centered rounded mark which was adequately stained, precise, clear enough to guide the surgeon to perform 5.5mm capsulorhexis.
Discussion
Fig. (1): Diagramatic representation of capsulorhexis marker.
Fig. (2): Capsulorhexis marker in the anterior chamber.
Fig. (3): Capsulorhexis mark on anterior capsule.
A well-constructed capsulorhexis is the foundation of complication-free phacoemulsification
and IOL surgery. Ophthalmic surgical dyes have
become valuable tools and are now widely used
for both anterior and posterior segment indications.
In this study we presented the capsulorhexis marker
which is applied directly on the anterior capsule
in order to help in better centration and sizing of
the capsulorhexis. Morever, it may guide phacoemulsification beginners and shorten their learning curve for this crucial step in modern cataract
surgery.
Today’s demanding refractive results require a
well centered perfectly circular capsulorhexis that
slightly overlaps the IOL’s optic. This construction
is important for achieving the so-called capsular
shrink-wrap effect during the postoperative period.
A 360° overlapping capsular edge creates a capsular
bend, which acts as a barrier against proliferating
lens epithelial cells and thus significantly delays
the onset of posterior capsular opacification (PCO)
[7-9] . The overlap also sets the anteroposterior
positioning of the IOL, which prevents capsular
fibrosis from shifting the lens optic forward and
creating an unwanted late refractive shift. Moreover,
with a perfectly circular capsulorhexis, any contraction of the anterior capsule (i.e, phimosis) will
be symmetrical, so late in-the-bag decentration of
the optic is prevented. The aspheric optics of the
AcrySof IQ Restor lenses (Alcon Laboratories,
Inc., Fort Worth, TX) and Tecnis Multifocal IOL
(Abbott Medical Optics Inc., Santa Ana, CA) tolerate very little decentration [10] . Also, if the
capsulorhexis is too small, it can result in glare,
Mohamed A. Hassaballa & Amr A. Osman
halos and night driving problems with a diffractive
multifocal IOL, such as the ReSTOR. Capsular
phimosis is more pronounced with small capsulotomies [11,12] . A small capsular opening makes
surgery more difficult and places greater stress on
the anterior capsule during nuclear division or
quadrant removal. Furthermore, a smaller capsular
opening can obscure peripheral retinal visibility
and treatment. A capsulorhexis with a 5.5-mm
diameter is usually ideal.
Many investigators have tried to improve the
predictability of size, shape and centration of
capsulorhexis. Wallace [6] performed a study to
make a central corneal mark with a 6.0mm optical
zone marker, previously used for radial keratotomy,
(with the center of the optical zone as the central
visual axis) as the patient fixates on the light of
the microscope. He performed the capsulorhexis
in the usual way with the intention of leaving the
borders of the capsulotomy inside the capsulotomy
diameter mark. However, this technique has many
disadvantages: As corneal curvatures are not uniform between patients, a different mark size would
be required for each patient to achieve the correct
capsulorhexis size. Moreover, use of this marker
incorrectly implies that corneal curvature remains
constant after the incisions are made [3] . Also, the
corneal plane and the anterior capsule plane must
be parallel with a focal plane of the operating
microscope to avoid parallax errors and the surgeon
may confuse the corneal mark with the anterior
capsule rim at the time of IOL implantation [13] .
Tassignon et al. [3] designed a 0.25mm ringshaped caliper with an internal diameter of 5.0mm
or 6.0mm (Morcher GmbH). The caliper is made
of polymethyl methacrylate. The caliper ring is
inserted using 2 forceps or a lens manipulator.
After it is inserted, the ring is gently pushed on
top of the anterior capsule with additional Healon
GV. A small opening is made in the center of the
capsule, which serves as the starting point for the
capsulorhexis. The surgeon then carefully follows
the internal border of the ring caliper. However,
this technique is not precise as the ring is not fixed
on the anterior surface of the capsule and thus any
movement of the ring will affect the size, shape
and centration of the capsulorhexis.
A promising technological solution involves
overlaying a reference ring on the surgeon's view
through the microscope. Carl Zeiss Meditec, Inc.,
developed an interface module that adjusts the size
of the ring appropriately with microscope magnification while keeping it centered within the limbus
using real-time eye tracking. Ophthalmic surgeons
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have such technology on excimer lasers, why not
for surgical microscopes as well? [14] . Finally,
several companies are developing femtosecond
technologies to perform the capsulorhexis.
Drawbacks and future:
In this study, we used a simple primitive prototype that needs a large corneal incision (6mm) to
be introduced inside the eye. We considered this
the first step in our research and we are looking
forward to change the material of the marker to
form memory ring able to be introduced and extracted inside the eye and become ergonomically
feasible. However, it can be used as such in cases
of combined cataract extraction with keratoplasty.
We studied the toxicity of the gentian violet dye
used with the marker on the ocular structure in a
rabbit's model. Results were promising and will
be published soon.
Conclusion:
Capsulorehxis marker is an instrument designed
to optimize the size, shape, and centration of the
capsulorhexis during phacoemulsification by impressing a circular pattern on the anterior capsule
to guide the surgeon in creating a 5.5- to 6.0-mm
diameter capsulorhexis. More refinement of the
instrument is needed to be able to use it in human.
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