LIMBOSIM: Virtual simulator for corneal transplants developed

It's a physical representation of the head's anatomy, complete with a layering artificial eye. Santander X Mexico awarded the project second place (2022). Currently, there are about 4,000 people on the cornea transplant waiting list.

LIMBOSIM: Virtual simulator for corneal transplants developed
The virtual simulator was developed to practice corneal tissue harvesting and transplantation. Image and text credit: UNAM

A multidisciplinary and inter-institutional team led by UNAM professors developed a hybrid surgical simulator for the training of health personnel involved in the cornea donation process, thanks to which self-sufficiency could be achieved on a national scale for this tissue, which today must be imported in almost 50 percent.

The innovation, called LIMBOSIM®, could be a turning point because it would mean a reduction in costs, since more than 80,000 pesos are paid for an imported cornea, and not all recipients have the possibility of covering that cost.

The project, winner of second place in the Santander X Mexico Award (2022), in the Acelera category, would make it possible to achieve national and massive training in the short term, and thus have more "corneas from Mexicans for Mexicans".

Sergio Teodoro Vite, professor at UNAM's Faculty of Engineering, told that the innovation to practice the corneal tissue procurement technique was created during the pandemic when Karla Verdiguel Sotelo, an academic at the National University's Faculty of Medicine and then president of the Mexican Association of Eye Tissue Banks, suggested the possibility of reactivating the training and organ and tissue donation programs. "There was a great need for simulation-based teaching materials."

Ariana Cerón Apipilhuasco, director of the Simulation Center for Clinical and Surgical Excellence of the Mexican Social Security Institute (IMSS); Efrén Huitrón Peralta, in charge of the virtual reality area of that institution; as well as Juan Salvador Pérez Lomelí and Luis Miguel Vidal Flores, from UNAM, were invited to collaborate as advisors for the project.

The team developed a physical model (mannequin type) to represent the anatomy of the human head, as well as an artificial eye with its layers, including the most important for this case: the cornea. After six months of work, the 3D design was obtained. Different materials were tested to simulate even the consistency of the eyelid skin.

There is also another virtual model of the simulator; it is a software that uses virtual and augmented reality to have a wider range of tools to practice the corneal tissue procurement technique, in case the physical model is not at hand, but a cell phone or a computer is, said Sergio Teodoro Vite.

Sergio Teodoro Vite's business project, which gave rise to LIMBOSIM®, was incubated at the Technology-Based Incubation Unit of the UNAM's Coordination of Technology Transfer and Linkage (CVTT), Sistema InnovaUNAM. The IMSS was the first institution to adopt the simulator to give a training course called "Cornea Code", which is carried out permanently.

LIMBOSIM: To help with the preparation for corneal tissue harvesting and transplantation, a virtual simulator has been created.
LIMBOSIM: To help with the preparation for corneal tissue harvesting and transplantation, a virtual simulator has been created.

A waiting list for LIMBOSIM®

Verdiguel Sotelo referred to the need in Mexico and other parts of the world for corneal tissue, the first one listed on the waiting list for a transplant. "It is documented that only one patient out of every 70 who require it is on the waiting list. We have a pressing need to obtain corneas and support those patients."

Based on the latest data, he detailed, we have more than four thousand people waiting for a transplant ordinarily, but there are also those who, in an emergency, depending on the tissue to safeguard the eyeball. "Today it is a priority health problem. It is necessary not only to train people but also to have it distributed throughout the country so that when a donation is positive or accepted by the relatives of a person who dies, it can be made concrete".

Before, ophthalmologists were the only ones trained to recover corneas from cadaveric donors, but since 2015 strategies have been generated to increase local donations, such as the training of technicians, optometrists, or biologists.

The specialist added that this process was previously carried out at the Institute of Forensic Sciences, but with time and corpse limitations, and in small groups. However, it was not enough for the donation programs in the country.

With this simulator "we could reach every state and in a constant manner, as required in donation; we would reach more students in less time," said Karla Verdiguel.

In addition, she stressed, with LIMBOSIM® we have explored the possibility of training surgeons to perform transplants. With some modifications to the first model, the simulator's capacity would be expanded; "we are already working on that. This would prevent the person from having to be trained abroad, as was the case years ago.

20 years ago, she recalled, we performed 10 or 15 transplants per year; today there are 15 per week. The growth has been exponential; however, we are a small group in charge of performing them. "There are hospitals that have been waiting eight years to benefit a patient; if this model is replicated in the different institutes and states, it will be of great benefit to patients", who range from 0 to more than 90 years of age.

Increased learning

Meanwhile, Ariana Cerón stressed that education has changed, and using the methodologies of the past no longer works. "Having a simulation center focused on postgraduate studies, where more complex competencies and skills are acquired, is a great help; being in a safe environment, with high realism, obviously gives a plus to the training."

The learning curve improves when using strategies such as simulators, and augmented or virtual reality. Continuing education is a challenge; unfortunately, there are not many training centers in hospitals.

Those who do with the model are physicians, but not necessarily ophthalmologists. In the middle of the virtual reality room, an eye is placed to remember the anatomical part, and then practice is done on the simulator. "It has been a total success and the learning curve has been exponential," agreed Efrén Huitrón.

Approximately 200 IMSS students (which is responsible for more than 50 percent of the donation and transplant activity in Mexico), including medical interns and coordinators, have had the opportunity to practice on the simulator, said Verdiguel Sotelo.

Finding more applications

Sergio Teodoro Vite mentioned that the business project began to be built in 2017, to provide an outlet for University and independent developments, specifically software that includes the use of interactive environments with virtual and augmented reality, as well as simulation, in areas such as energy and health. It was submitted to CVTT for approval, and when it was being incubated, the idea of the simulator was born.

The trademark was created and the intellectual property registration was obtained from the Mexican Institute of Industrial Property for the model; copyright registrations were also made for the simulator and the software, which is an auxiliary of the physical model. Now, to create more simulators that can be used in state transplant centers, we submitted the project to the Santander competition. "The jury liked it and we were awarded second place.

Thanks to the award we have economic resources to mature it: the goal is to add greater realism to the physical model, and to incorporate virtual and augmented reality so that the virtual model can evolve and find other applications, he concluded.