It can be said that ophthalmic surgical exercise using pig eyes is common but not casual enough, so such training may not be a sustainable practice. As a result, inexperienced trainees sometimes have to perform surgery on patients before their skills are well developed1. Our simulator, using a spherical silicone mold, can become the solution to the abovementioned problem. This silicone material has not only a size similar to an eyeball but also moderate flexibility that closely resembles the sclera, and it can realize an ideal training environment. Moreover, its semitransparency and open-sky structure are suitable for observation from the intraocular side or from outside of the eye globe. Currently, most surgical instruments have become disposable and are discarded after a single use. However, in this simulator, the use of these instruments can help to create a surgical environment similar to that in such facilities. These characteristics allow for simulated surgery without having to travel to special facilities that offer plenty of pig eyes and vitreous surgical machines. Therefore, effective and sustainable surgical training in a distorted environment, such as the COVID-19 pandemic, may be realized.
Recently, the progress of surgical training appliances using VR, for example, EyeSi as a representative, has been remarkable1, 4–7, 13, 14. However, EyeSi is extremely expensive and not generally used yet15. Other simulators from previous reports2, 8–12 have been fascinating for perceiving direct feedback. Some of them simulated surgery using eyeball models from marketing products8, 10. These were high quality but also relatively expensive11, while spherical silicone molds were able to obtain for approximately 2 dollars in the Japanese net market at the time of this experiment. In addition, these silicone molds seemed to be available for less than 10 dollars in the net market written in English, which suggests that anyone can casually purchase them in many countries. Rice et al. also reported a similar low-cost simulator that had an open-sky structure and that was crafted by a table tennis ball11. This eye model had a 40-mm diameter, which seemed to differ in terms of size and rigidity compared to a real eyeball, while our spherical silicone mold had an approximately 25-mm inside diameter and moderate flexibility.
A challenging problem was how to reproduce extremely thin biomembranes, such as an inner limiting membrane of approximately 1–5 µm16. We tried numerous kinds of tapes and paint materials. Unfortunately, silicone prevented them from adhering well, suggesting that they were not recommended for peeling. Nail polishing and adhesive for silicone material were thought to be sufficiently effective, but several hours were needed for drying. To overcome these disadvantages, several spray materials were verified, referring to past reports10, 11. Consequently, Scotch Spray Glue 55 was chosen due to the advantages that it was easy to make it thin and that its drying time took only approximately 10–20 minutes. The touch to peel this material was like sticky ERM. Other unknown ingredients with the potential to produce an excellent membrane have not been sufficiently examined; thus, further studies on membrane materials are necessary.
This simple shape may bring about further creative uses. For instance, we made the original assessment scale using our device in reference to previous reports17, 18 (Fig. 2). We intend to launch this evaluation for trainees, and safer vitreoretinal surgery would be expected. If enthusiastic surgeons do not have surgical instruments or mannequins, they can perform borderless self-training by substituting wires and a plastic bottle cap (Fig. 3). It may be used for surgical discussions in academia. Many other possibilities are expected depending on the user’s objective and individual intellectual contributions.
This simulator has obvious limitations, such as the absence of cornea, lens, and vitreous body. In fact, it does not correspond to all vitreoretinal surgical maneuvers. However, almost all of our hospital's vitreous experts and ophthalmological residents were impressed by its quality. Overall, it may be said that this is a novel self-made vitreoretinal surgical simulator due to the abovementioned reputation and usefulness. Further investigation in many other facilities will be needed, but we hope that this report will help young vitreous surgeons and patients worldwide.