feature
Surgical
Simulator Helps Train Young Surgeons
New technology provides another avenue
to learn and refine surgical skills.
FAREED ALI, MD, FRCS(C)
Vitreoretinal surgery is a difficult and technically
demanding skill to acquire. The beginning vitreoretinal surgeon must master the
technique of coordinated use of both hands and both feet to control various microscopic
instruments, the microscope, and the vitrector system. In addition, the skills necessary
to manipulate the most delicate and sensitive tissues in the entire human body must
be acquired while avoiding unnecessary damage to the eye.
Traditionally, young surgeons learn these skills during residency
and fellowship training and utilize wet labs involving pigs or cadavers' eyes. The
initial training is followed by observing and assisting experienced surgeons, and
eventually, fellows and residents perform surgery on actual patients.
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The sensor and camera systems of the EYESI
allow real-time three-dimensional tracking of multiple instrument positions within
the simulated eye.
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While the traditional methods are tried and true, there are limitations
to using such methods. Pig eyes, of course, are not identical to human eyes in terms
of size, shape, and the feel and structure of tissues. Human cadaver eyes can be
difficult to acquire in some instances and present a theoretical concern regarding
biological hazard risks. Also, without objective critique, a significant element
to a surgeon's medical training remains incomplete.
One company is changing the way that new retinal surgeons are
trained, and in the process, may revolutionize the way that all retinal specialists
learn new techniques.
VRmagic, based in Manheim, Germany, has developed the EYESI virtual
reality vitreoretinal surgery simulator system. An important function of the EYESI
is its ability to evaluate the surgeon's ability to perform a predetermined simulated
task by generating an objective score. This allows trainees and supervisors to monitor
progress and continued improvement in surgical skills.
The system consists of a surgical microscope positioned above
a model of a human head. Within the head is a representation of the globe that has
realistically positioned ports for inserting the vitrectomy instruments. The globe
can be moved within the eye socket, which allows the surgeon to use instruments
to torque and position the eye during surgery.
Foot pedals are also integrated into the system, allowing the
trainee to utilize a microscope and vitrector controls. The microscope system must
be properly focused and positioned during surgical simulations. The EYESI can also
simulate the use of the binocular indirect ophthalmoscopes' (BIOM) inverter viewing
system and controls. Additionally, the system allows the trainee to gain experience
with adjusting vitrector parameters, such as suction, flow, and cutting speed.
THE TECHNOLOGY'S DEVELOPMENT
Markus Schill, PhD, CEO, and one of the
founders of VRmagic says the technology behind the EYESI simulator has its origins
in his master's thesis work. He was attempting to develop a computer model to simulate
brain edema related to craniotomy procedures for treating trauma. However, the algorithms
he used did not allow for a fast-responding real-time simulation, so he decided
to turn his attention to ocular surgery.
"The eye was the perfect organ for developing this technology,"
says Dr. Schill. Although he has no formal ophthalmology background, Dr. Schill
consulted several German ophthalmologists while developing the EYESI — including
Michael Knorz, MD, an anterior segment surgeon based in Manheim, and vitreoretinal
surgeons Frank Koch, MD, based in Frankfurt and Klaus Lucke, MD, of Bremen.
With the development of this technology, Dr. Schill says his native
Germany has replaced using pigs' eyes in favor of virtual reality to teach surgery
to students.
"We have now reached a paradigm shift where the German Retinal
Society will no longer use pig eyes for vitreoretinal surgery training."
FEATURES
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VRmagic's EYESI system helps train vitreoretinal
students by providing a virtual reality surgical experience. |
The student surgeon handles instruments,
which provide a realistic feel, and can also observe the manipulations through a
stereoscopic simulation of a surgical microscope view. The EYESI system tracks about
25 different intraoperative parameters, such as surgeon hand tremor, physical pressure
on the retina, light toxicity, intraocular pressure, and amount of contact with
the lens — all measures that could be used for performance evaluation.
Immediate visual feedback is provided to the surgeon based on
the position and actions of the instruments. For example, a visual simulation of
an epiretinal membrane being peeled is the result of the correct use of the micro
forceps. However, if the forceps makes excessively firm contact with the retina,
then the surgeon observes whitening or even hemorrhage of the retina.
"I was actually quite astounded with how realistic it was," says
T. Mark Johnson, MD, a vitreoretinal surgeon at the National Retina Institute (NRI)
in Chevy Chase, Maryland, of his first impressions with the EYESI simulator. "You
can really get lost in the machine; you forget you are not really operating."
In addition to standard simulations of vitreoretinal procedures,
the EYESI can also present the surgeon with various tasks, such as grasping a cylinder
within the vitreous with micro forceps and placing the cylinder inside a ring within
a set time limit. The integrated computer screen allows observers and teachers to
view the progress of the surgery and manipulate the operating conditions. The EYESI
also provides an objective scoring system for each procedure. This feature tracks
skills improvement and can identify areas of weakness that the trainee needs to
work on.
TRAINING
EYESI is well-suited for teaching hospitals
or practices that continuously train fellows. Dr. Johnson's center acquired the
EYESI system about 18 months ago for the NRI's vitreoretinal training program, and
they have developed a unique approach to integrating the system into their training
process.
"We found from the perspective of fellows, it is a great tool.
But like many great training tools, unless there is a proper system in place for
trainees to apply what they learn, they do not get a lot out of it. A curriculum
is needed to enhance its effects as a teaching tool," says Dr. Johnson.
NRI partnered with a company that specialized in airline safety
training and flight simulators, and developed some prototype teaching modules that
break down the surgical skills needed into a series of tasks for residents and fellows.
Dr. Johnson has already seen the EYESI result in some significant
changes in his vitreoretinal training program. "It has pretty much replaced the
traditional wet lab," he says. "I think, to some degree, it has reduced the anxiety
you feel when you first let a trainee operate on a real patient."
Dr.
Johnson also sees the potential for using the EYESI to train nonsurgical members
of the operating room team. "Everyone has had the experience of working with an
OR team not versed in retinal procedures," he says. "The potential is there to make
this applicable to training OR nurses and techs. Our next step is to develop the
framework for modules for training non-surgeons."
There are indeed benefits to training nonsurgical members, such
as increased patient safety and comfort and improved overall surgical efficiency
in terms of operative time and costs.
David Chow, MD, vitreoretinal surgeon, St. Michael's Hospital
in Toronto, Canada, has also incorporated the EYESI system into his training activities
for his residents and fellows. His use of the EYESI has provided some interesting
insights into young surgeons' capabilities.
"It has been interesting to see the skill levels in junior residents
on various tasks. Many are very good at manual dexterity skills, but once surgical
procedures or problem solving is required, they show their 'immaturity'," acknowledges
Dr. Chow.
He adds, "the software actually punishes surgical performance
more severely than the actual human eye in many cases. So if you can pay attention
to the issues that the software is training you to avoid, then you will do well
in the human eye."
Dr. Chow would like to see the EYESI system used as part of accreditation
and licensing examinations. "At present there is really no way to truly know if
a graduate is safe in an eye surgically and can handle a complication."
CHALLENGES
The greatest challenge faced in developing
the EYESI was overcoming the virtual reality of the system. "In reality, all of
our senses are smoothly integrated — this is not easily represented on a computer,"
notes Dr. Schill. "If there is a noticeable time lag between moving the simulated
instruments and seeing the expected effects, then the brain will not be fooled."
This time lag is dependent upon the computer algorithms and models
at the heart of the EYESI. In addition to the computer models, VRmagic has pioneered
the development of sophisticated camera technology and optical tracking systems.
These systems are so effective that VRmagic licenses the technology for third-party
usage.
A possible short-coming of the system is that a surgeon's score
is mainly derived from the amount of time taken to perform a given task. "There
are some issues with how it derives the score – the scoring is now a little
too weighted toward time at the expense of evaluating mechanics and safety. There
are parameters it can measure that give objective feedback and the modules we have
developed help identify what areas the trainee is having difficulty with," says
Dr. Johnson.
As good as the EYESI system is, Dr. Johnson sees the potential
for improvement in some other areas as well. The analogy is made with airline flight
simulators. "Flight simulators can simulate situations arising from known potential
aircraft design flaws. From repeated use of the simulators, the pilots then know
how to land the plane in that situation. If it happens in real life then the scenario
is not as stressful," says Dr. Johnson.
He would like to see the EYESI incorporate various complications
that can occur during vitreoretinal surgery. He would also like to see improvements
made in the instruments used with the system. "The instruments used in EYESI are
multifunctional and foot activated which is different from what we usually use,"
adds Dr. Johnson.
SYSTEM UPGRADES
Further advancements are planned with the
existing anterior segment surgery module, as VRmagic recognizes anterior segment
surgery simulators would likely have a larger market than the retinal market. Besides
VRmagic's own developments for cataract surgery, there is also a capsulorrhexis
module being developed with a third party based in Pennsylvania.
"There is also great interest from surgical equipment companies
who would like to integrate the particular features of their vitrector machines
into the EYESI," says Dr. Schill. Companies such as Alcon, AMO, Geuder, and Bausch
and Lomb have reportedly expressed such interest.
REFINING SKILLS
Dr. Chow has found the EYESI system to be
useful in helping to improve his own surgical skills. For example, he has used it
to improve his performance with his non-dominant surgical hand. Dr. Chow is also
using the EYESI as a research tool to evaluate various factors such as caffeine,
alcohol, and sleep deprivation on surgical performance.
Dr. Chow has found overall the EYESI to be a technically reliable
and user-friendly system that is very easy to use with good technical support from
VRmagic. "It is an impressive piece of technology whose time has come," adds Dr.
Chow.
Fareed Ali, MD, FRCS(C)
is a retinal specialist and director of clinical research at the Canadian Centre
for Advanced Eye Therapeutics based in Mississauga, Ontario (www.retinamd.ca). Dr.
Ali has no financial interest in the information contained in this article. He can
be e-mailed at drfali@sympatico.ca.
Retinal Physician, Issue: May 2006