JAN 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/78721

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Page 57 of 71

58 EW RESIDENTS January 2012 Cataract tips from the teachers Practice makes perfect: But how in the wet lab? bers I modify the techniques. The corneal incisions are made more corneal and the capsular tears redi- rected to avoid them swinging out. I encourage residents to work Sherleen Chen, M.D. Assistant professor of ophthalmology Harvard Medical School Director of Cataract and Comprehensive Ophthalmology Massachusetts Eye and Ear Infirmary Joel Reisman, M.D. Assistant professor of ophthalmology and director of Resident Wet Lab Tufts University School of Medicine, Boston Roberto Pineda, M.D. Assistant professor of ophthalmology Harvard Medical School Director of Refractive Surgery Massachusetts Eye and Ear Infirmary My goals for residents in the wet lab are: 1) Learn the basic steps in phacoemulsification; 2) Learn how to use an operating microscope; 3) Know the parameters and settings of the phaco machine; and 4) Become familiar with the names and uses of instruments. We then give residents the Wet lab rehearsal is an essential component in preparing for intraocular surgery. One difficulty in practicing for phacoemulsifica- tion is to find models and conditions that accurately simulate the tissue response, anatomic constraints, and atmosphere of operating on the human eye. We've asked three experienced cataract surgery instruc- tors for their best ideas and tips on practic- ing the steps of phacoemulsification and preparing for surgery in the wet lab setting. Sherleen Chen, M.D., and Roberto Pineda, M.D. unique skills to coordinate all the different aspects of phaco surgery— left foot microscope pedal, right foot phaco pedal, sideport hand, phaco hand, and phaco sounds—all into a smooth dance. This multitasking is the key to good eye surgery. I teach using positive reinforce- ment, praising each small step in the learning process. When demonstrating the use of the operating microscope, I recom- mend residents begin and stay with the lowest magnification because the greater depth of field makes it easier to operate. I also encourage them to refocus the microscope often during the procedure. I usually ask the company repre- sentative to go over the phaco ma- chine in depth in order for the residents to learn all the parameters and settings for both phaco and an- terior vitrectomy. In order to initially build a little confidence and minimize frustration in learning capsulorhexis, I begin using artificial eyes then move on to pig eyes. I have tried making cataracts on the pig eyes using the microwave and formaldehyde/alcohol injec- tions but do not find it to have much teaching value. The pig eyes are held securely with a vacuum holder. The names and functions of the instruments are learned along with the best way to hold them. Because pig eyes have thick capsules and shallower cham- A. Tim Johnson, M.D., Ph.D. Professor of clinical ophthalmology and service director, Comprehensive Ophthalmology Clinic University of Iowa, Iowa City Over the course of each year, I have the opportunity to interact with nearly 300 residents from all over the country. I enjoy the enthusiasm and energy the residents bring to improving their skills in the wet lab. I learn something each time I teach in the lab. I have worked with various sys- tems, but have by far the most teaching experience with the pig eye. Success with the pig eye is de- pendent on maintaining a clear cornea. A fresh source of eyes is criti- cal. Corneal clarity can also be main- tained by applying a 15% dextran (Swinger-Kornmehl) solution.1 Per- forming a capsulorhexis in a pig eye is challenging and is distinctly dif- ferent from performing the proce- dure on an adult human eye. The slowly and deliberately and to stop or slow down when they get into trouble. All too often there is a ten- dency to speed up when having problems. When using the phaco hand- piece, I want them to picture the lens as a sphere so that when learn- ing to groove, they sculpt while knowing where the capsule lies. I try to have them coordinate the physi- cal and visual sculpting with the po- sition of the pedal and the sounds of the machine. Our microscope has a video camera so that we can teach as a group. The best way of learning and remembering is to teach, and therefore I have the residents in- struct the medical student in each step of the surgery the same way that the other attending and I taught them. pig capsule is significantly thicker and more elastic. The capsule can be modified by adding fixative to make it behave more like the human cap- sule. I use an equal mixture of for- malin and viscoelastic, plus a little bit of trypan blue to make the cap- sule more visible. This solution can be applied to the capsule either under an air bubble or under vis- coelastic (after creating an aqueous layer over the capsular surface with balanced salt solution). Using the cannula to paint the solution on the surface of the capsule helps ensure even distribution. Be careful not to use too much solution, as the fixa- tive can contribute to clouding of the cornea. The nucleus can be hard- ened by microwaving the eye for 6-7 seconds or by injecting fixatives di- rectly into it. The pupil is normally way too large to be useful for prac- ticing advanced techniques, but a properly sized capsulorhexis can be used as a pupil for the purpose of practicing placement of a Malyugin ring (MST, Redmond, Wash.) and even suture fixation of a three-piece lens. I have tried several artificial sys- tems, and the one I find most useful is the Kitaro surgical training system (Frontier Vision, Japan). One nice feature of this system is its modular nature. The eye is assembled from various components, which are switched out after each procedure. Virtually every step of the proce- dure, including incision, capsu- lorhexis, and phacoemulsification, can be practiced with this system. There is a roll of capsular material for endless practice with the capsu- lorhexis. There are nuclei of varying hardnesses to practice lens disassem- bly techniques. The cost of the sys- tem is nominal for a training institution. Cynthia Chiu, M.D. Associate professor and director, Comprehensive Ophthalmology & Optometry University of California, San Francisco continued on page 60

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