Sherleen Chen, M.D.
Assistant professor of ophthalmology Harvard Medical School Director of Cataract and Comprehensive Ophthalmology Massachusetts Eye and Ear Infirmary
Roberto Pineda, M.D.
Assistant professor of ophthalmology Harvard Medical School Director of Refractive Surgery Massachusetts Eye and Ear Infirmary
Technology is advancing at a lightning pace, and with it is the learning process. We email, text, and tweet our colleagues, fellows, and residents, and this has quickly replaced the concept of being "on call." Surgical training is similarly progressing as we increasingly use simulators to assess performance instead of animal models. This shift toward artificial environments has spurred the use not only of simulators but of synthetic eyes in the acquisition of surgical skills to more readily emulate the "real McCoy" in learning ophthalmic surgery. In this column, our cataract teachers will review their experience with these devices and express their likes and dislikes with the new technology in helping our junior colleagues gain valuable surgical experience.
Sherleen Chen, M.D., and Roberto Pineda, M.D.
Yousuf M. Khalifa
Assistant professor, Department of Ophthalmology University of Rochester Medical Center School of Medicine and Dentistry Rochester, N.Y.
Dr. Khalifa: Resident surgical training can be approached from a variety of ways. Traditionally, the resident gained experience in a stepwise fashion with graduated responsibilities. As oversight of residency training has expanded and competencies introduced, a trainee's surgical skills are no longer judged by length of training or number of cases. The onus is now to establish surgical competency—a difficult task.
How do we prepare our residents for the responsibilities of
primary surgeons? Once they have started operating, how do we help them improve and grow? How do we verify after 3 years of residency that they have gained sufficient knowledge? Simulation in ophthalmology surgical training usually involves porcine eyes. Fresh tissue is excellent for practicing incisions and scleral and corneal suturing. Cataract
surgery training using animal eyes falls short when it comes to capsulorhexis and phacoemulsification. The capsule of the porcine eye is rubbery and the lens quite soft, and the resident practicing on this type of model fails to develop techniques that are transferrable to the operating room and, even worse, may
develop techniques that are counterproductive for successful cataract surgery. Using a microwave to induce nuclear sclerosis and combining this with formaldehyde fixation improves the porcine model, but the difficulty of obtaining fresh tissue, the risk of infection, and the hassle of storage and disposal remain
We continue to use porcine eyes for wound construction and wound closure instruction, but intraocular simulation of capsulorhexis, phaco grooving, nucleus disassembly, quadrant removal, I/A, and IOL placement is now done on the
Kitaro WetLab system (FCI Ophthalmics, Marshfield Hills, Mass.). We have found the accuracy of the simulation to be excellent. We
believe the fidelity of this system will fundamentally change the role of phacoemulsification training outside the operating theater. The feel of the capsulorhexis is quite real, and many advanced techniques can be taught such as saving a rhexis that is running out or can opener capsulotomy. Phaco grooving using the Kitaro WetLab system provides the resident with an opportunity to appreciate depth of field and learn the three foot pedal positions. Nucleus disassembly is a complex
bimanual maneuver that can be difficult to master in the operating room, but with the Kitaro magnetic mounting system, the effect of surgeon force on the globe is simulated, and the resident learns to control centration during this step. The weakest part of the Kitaro simulation has been the irrigation/aspiration step because the remaining "cortex" actually behaves like epinucleus and comes out like a shell. We have adapted the Subjective Phacoemulsification Skills Assessment for our wet lab curriculum and call it the Subjective Phacoemulsification Wet Lab Skills Assessment. Residents are assigned a task in the wet lab and asked to digitally record multiple examples of their technique. Each assignment is preceded by a didactic lecture and live demonstration in the wet lab. The residents have a week to complete the assignment and submit it for grading. The simple addition of a video recording requirement makes the wet lab much more effective because the resident is working toward a final product of which he or she wants to be proud.
With the growing number of factors that often limit opportunities for resident surgical education, it is of great importance that effective methods of phacoemulsification training be developed. Objective, valid, and reliable tools that provide rapid feedback are essential for training in the wet lab and in the operating theater. We are not there yet.
Lisa Park, M.D.
Clinical associate professor Associate residency program director Department of Ophthalmology NYU School of Medicine, New York
Dr. Park: An important aspect of learning phacoemulsification is the use of practice systems prior to operating on patients. The traditional wet lab has utilized animal or cadaveric eyes, requiring a dedicated facility where human surgery does not take place. Obstacles to having a successful wet lab include set-up costs, maintenance, and disposal of bio-hazardous materials, as well as provision for off-hours access. The use of synthetic eye systems attempts to address some of these issues. I recently had the opportunity to use the Kitaro WetLab and DryLab kits, which were developed by Junsuke Akura, M.D.
The kits consist of a plastic base with two "orbits" in which magnets hold a scleral base in place. A cornea/iris piece snaps onto this shell, and a rubber facemask is placed on top. What differentiate the dry kit from the wet kit are essentially the pieces that snap onto the scleral base. The dry kit utilizes an "open sky" plastic cornea with sideport openings for the cystotome and capsulorhexis forceps. The
cellophane capsular material is easily replaced for multiple uses. The wet kit utilizes disposable corneas and
nuclei of various densities, which are consumed during phacoemulsification.
We recently utilized this system at the 2012 NYU cataract course attended by residents throughout New York. The feedback was very positive; there was no need for surgical gowns and no variability from one specimen to another. For the novice surgeon, the opportunity to practice surgical skills was excellent, and for the experienced surgeon, the artificial eye provided a good model for teaching basic concepts.
One of the main advantages is that this is a clean system and theoretically can be taken to the
operating room and used without contaminating surgical equipment. Another is convenience—the entire system is packaged in a portable case; this is particularly useful for practicing the capsulorhexis using loupes.
The main disadvantage of this system is cost. The consumables include the cornea and nuclei, and although the company claims that the cornea has multiple uses, our experience has been that this is not ideal. Replacing these pieces yields a cost of approximately $50 per eye. In comparison to animal eyes, which can be obtained for minimal to no cost, this is a significant expense.
Overall, however, I believe the Kitaro is worthwhile as an artificial eye system and a good teaching tool.
James P. Dunn, M.D.
Associate Professor, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore
Dr. Dunn: Cataract surgery lends
itself nicely to practice under a
microscope. It is mandated in the Accreditation Council for Graduate Medical Education (ACGME) Residency Review Committee's Common Program Requirements for ophthalmology that each training program has a functional practice surgery lab for residents. In many cases, animal eyes (lamb, pig, cow) are used, but access to such eyes may be limited, their size may render them as a less-than-optimal substitute for human eyes, and the tissues—particularly the capsule and the lens—often behave differently from those of adult human eyes. Porcine capsules, for example, have tensile properties much more like a pediatric human capsule. Cadaveric human eyes are expensive (roughly $200 each) and are rarely an option. Some programs now have access to virtual cataract surgical simulators such as the EyeSi (VRMagic, Mannheim, Germany), but cost remains a significant impediment, and virtual reality systems, while potentially very useful, lack the sort of kinesthetic feedback that is essential for residents to experience. Consequently, many programs in the U.S. and abroad now use synthetic eyes.
While not usually considered a "synthetic eye," cherry tomatoes (boiled and then chilled) and grapes can be useful models for practicing a capsulorhexis. The Red Globe variety of grape may be up to 1 inch in diameter, suitably large for practice with Utrata forceps, and the skin has a mechanical tension similar to that of the aging lens capsule.1 Several synthetic models are available at reasonable prices that provide fairly realistic kinesthetic feedback. The first is from Kitaro. The dry lab component has different materials for manually practicing capsulorhexis, nuclear dividing
techniques, wound construction, IOL insertion, and even simulated eye movements using a unique
magnet attachment. The wet lab comprises an artificial cornea and lens with distinct capsular, cortical, and nuclear components for use with a phaco machine. The lenses come in different densities. Gulden Ophthalmics (Elkins Park, Pa.) makes an ergonomic
simulator eye for practicing the
basic steps of phaco surgery, i.e.,
capsulorhexis, sculpting and four-quadrant grooving, bimanual cracking into four quadrants, chopping, and emulsification of the nucleus. Replacement lenses are available at $5 each.
Phillips Studio in the U.K. makes a life-sized synthetic eye in which the hardness of the nucleus can be adjusted, allowing residents to practice different phaco techniques as well as capsulorhexis. Replacement eyes are $20 each.
While no comparative studies of the utility of these different models have been published, many program directors find them extremely helpful. Above all, residents should remember that ANY surgical practice can be beneficial if a well-planned surgical curriculum is available that includes proper use of the options described above.
Figueira EC et al. The grape: An appropriate model for continuous curvilinear capsulorhexis. J Cataract Refract Surg 2008, 34:1610-1.