: Simulation training key to learning strabismus surgery techniques


For many surgeons, technology is replacing old methods , including the use of cadaver eyes.

Reviewed by Will Turk, MD

Simulation training of strabismus surgery offers several advantages, according to Will Turk MD, an ophthalmologist and fellow in oculoplastic, orbit, and ocular oncology surgery at the University of Calgary in Alberta, Canada.

“How do we currently teach residents strabismus surgery?” asked Turk, noting residents traditionally have been taught under direct supervision by experienced mentors. “In most programs in Canada, it is essentially on-the-job training. Typically, we are teaching residents in the operating room on live patients. There is graduated responsibility over time.”

Some of the things to consider in strabismus surgery in pediatric ophthalmology is the duration of the surgery, the young age of the patient, and the need for general anesthesia, Turk said during a presentation at the virtual 32nd Annual Jack Crawford Day, a pediatric ophthalmology update held each year and organized by the University of Toronto and the Hospital for Sick Children in Toronto, Ontario, Canada.

The traditional teaching in a strabismus wet lab has involved the use of rabbit heads or cadaver eyes, according to Turk.

“We are not using rabbit heads for simulated surgery currently,” Turk explained. “There are a lot of limitations to this method of wet lab teaching. It is resource-intensive to acquire the rabbit heads. They only last for a limited time. They are single use. They are not easily transportable. They are a biohazard and have to be disposed of afterward. They are relatively expensive. There is also the ‘ick’ factor.”

Turk and Christian Petropolis, MD, FRCSC, a plastic surgeon from the University of Manitoba, invented a 3D-printed silicone model for practicing and teaching strabismus surgery. The model offers advantages such as patient safety, accelerated learning, reduced costs, increased operating room efficiency, and group learning, according to Turk.

“I think the No. 1 thing is that it improves patient safety by having residents operate in a risk-free environment,” Turk said. “There is accelerated learning because it is an opportunity for residents to get a good foundation of surgical skills and fine motor skills prior to entering the operating room.”

Moreover, Turk explained that there is increased efficiency and reduced costs, which are particularly important when pediatric wait times are so long.

“There is also the possibility of group learning whether it is with fellow residents in their own program or across the country or even across the world,” he said.

Strabismus surgery practice in the simulation lab, like other ophthalmic surgeries, is quickly becoming the norm in ophthalmology residency programs, said Turk.

The pilot experience with the 3D-printed silicone strabismus model took place at the annual meeting of the 2017 Canadian Ophthalmological Society (COS) meeting in in Ottawa, Canada, at the Strabismus Skills Transfer Course created by Yi Ning Strube, MD, noted Turk.

Since the initial pilot experience at the COS meeting, the model was used at the annual meeting of the American Academy of Ophthalmology that same year, where it was compared to the traditional rabbit heads, as a way of learning how to perform strabismus surgery.

The model was also used at the World Congress of Pediatric Ophthalmology and Strabismus in 2017 in Hyderabad, India, noted Turk.

“World experts had an opportunity to see the model and use the model,” he said.

Turk and collaborators, including Strube, a pediatric ophthalmologist, and ophthalmologist Lisa Jagan, MD, FRCSC, published data on the experience with strabismus teaching models, including the 3D-printed model. Their research was highlighted on the front page of the Journal of American Association for Pediatric Ophthalmology and Strabismus.1

Investigators asked participants to complete a validated questionnaire to assess the fidelity of the experimental model and the rabbit head. They were asked to provide overall ratings of the globe, conjunctiva, muscle, and scleral fidelity using a 5-point scale.

A total of 47 participants completed the questionnaire. The model head rated 18% higher than the rabbit head for anatomical accuracy and 25% higher for position of eyes within the head. Investigators found that more experienced users were more likely to strongly agree that the silicone conjunctiva effectively mimics real conjunctiva.

“The conclusion from the study was that the model did provide an excellent platform for simulated strabismus surgery,” said Turk. “There was validity of the model compared to the rabbit head model in terms of model fidelity.”

This 3D-printed strabismus surgery model has now replaced the rabbit head and has been used since 2017 at the yearly Strabismus Surgery Skills Transfer course taught at the AAO, and most recently at the Strabismus Surgery Skills Transfer course at the COS annual meeting in June 2022.

The key to strabismus simulation surgery is the use of 3D printing, noted Turk. Because the cost of 3D printers has come down appreciably, it is much more viable to build the models and use them for the purposes of teaching strabismus surgery, according to Turk.

“We can now be physicians who are engineers as well,” said Turk. “The benefit of that (3D printing) is that you can rapidly prototype different models. You can print them. If something is not working out, you can make a new design and have a new prototype the next day. (3D printing) has revolutionized what we have done, have been able to do and develop.”

Those practicing surgery at home can record themselves, for review by a preceptor at a later date, noted Turk. “The end game is developing a curriculum and incorporating the model and the assessment tools,” he said.

The 3D-printed model will fit well with competency-based medical education, which, Turk said, together with surgical simulation training, is the future of ophthalmology education in Canada.

The 3D-printed strabismus surgery model is now available for academic institutions and those interested in strabismus surgery, funded through the nonprofit Wright Foundation for Pediatric Ophthalmology and Strabismus. Please contact Yi Ning Strube, MD, for more information on the Strab Lab Surgical Model: yining.strube@queensu.ca.


Jagan L, Turk W, Petropolis C, et al. Validation of a novel strabismus surgery 3D-printed silicone eye model for simulation training. J AAPOS. 2020;24(1).3.e1-3.e6. doi:10.1016/j-jaapos.2019.10.008

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