Eyeworld

EW RESIDENTS 30 November 2011 What is the best way to practice a continuous curvilinear capsulorhexis? Saraswathy Ramanathan, M.D. California Pacific Medical Center, San Francisco T he capsulorhexis has a rep- utation for being the most difficult part of phacoemul- sification surgery. To make things worse, if the first capsulorhexis is performed on a pa- tient in the operating room, anxiety may prevent the learning surgeon from having a successful outcome. The key to mitigating anxiety is to prepare and practice prior to arriving in the OR. My residents often ask me how to prepare and practice. Here are a few of the teaching points that I give them. Preparation Think of the capsulorhexis as a series of repeating steps. Understand each step and what is required to achieve success. For me, those steps are: puncture, scratch, initial tear/flap creation, segmental tearing, and re- grasp. The importance in prepara- tion comes with thinking of each of these as a distinct step, requiring de- liberate thought. Often I find that a learning surgeon will hurry through the puncture and scratch steps in order to get to the tearing steps. Un- fortunately, if the puncture and scratch are done poorly, the rest of the capsulorhexis becomes more dif- ficult. If on the other hand, the learner thinks of each portion as its own step and practices with that mentality, there is likely to be in- creased success with each portion and in the capsulorhexis as a whole. Practice There are many ways to practice cap- sulorhexis prior to arrival in the OR. I often recommend a staged progres- sion from non-eye models to animal or cadaver eyes. Though it may seem a bit unusual, my favorite non-eye model is a lightly poached tomato. It works well, as the skin is thin relative to the fruit, and the poaching process creates steam between the fruit and the skin, thus loosening it enough to allow the skin to be torn. Also, the curvature of the tomato can ap- proximate the anterior surface of the lens. To poach, dip a firm but ripe tomato into boiling water, making sure the tomato is fully immersed. After about 10 seconds, remove the tomato and put it in a bowl of cold water to stop the cooking process. When cool, draw an 8-millimeter circle on the tomato (to simulate a dilated pupil) and place two small push pins 3-4 millimeters apart to simulate a corneal tunnel. Practice the tomato capsulorhexis either under the microscope (at work) or with loupes (at home). The advan- tage of the tomato is that it is readily available, and the vector of force in- volved in tearing is very similar to that needed in the human eye. The disadvantage is that the tomato skin is thick and requires more course manipulation than with the human. Once the tomato has been mastered (this doesn't take long), move on to the animal eye that has been mi- crowaved for about 8-10 seconds (to denature and coagulate the lens pro- teins a bit). Animal eyes have their advan- tages and disadvantages. The main advantage is that a real eye will teach the learner to work within the space allotted and to pivot the in- struments within the wound. The main disadvantage is that the vector forces required to make a capsu- lorhexis in the highly elastic animal lens capsule are not the same as the forces required in the human. Ca- daver eyes, while better in terms of the lens capsule elasticity, often have very cloudy corneas and are difficult and expensive to obtain. Though neither the tomato nor animal eye is ideal as a model for capsulorhexis, but the use of both together allows the learner to ap- proximate the steps, force vectors, and space constraints involved in creating an excellent capsulorhexis. Preparation with these models will greatly alleviate the anxiety associ- ated with capsulorhexis and allow greater success intraoperatively. Andrew Thliveris, M.D., Ph.D. Associate professor, University of Wisconsin, Madison As all of us would agree, a flawless curvilinear capsulorhexis is paramount in ensuring an uncom- plicated cataract extraction. Unfor- tunately, it is one of the most difficult aspects of the surgery. One reason for this is the number of vari- ables that exist when performing this part of the procedure, which can include the size of the pupil, globe exposure, red reflex, nature of the capsule texture, and the consis- tency of the underlying lens (vary- ing from a firm to even liquid state with an intumescent cataract). These variables have historically been difficult to simulate in a practice or laboratory setting. Obtaining com- petency in perfecting the curvilinear capsulorhexis has been achieved by the use of animal and human ca- daver eyes, surgical simulators, and to some degree the human patient. Our teaching methodology W hat is the best way to practice a continuous curvilinear capsulorhexis? Perhaps one of the most challenging and anxiety-provoking steps for beginning cataract surgeons is learning how to proficiently and consistently perform the capsulorhexis. From initiating the cap- sulorhexis, to controlling the tear, its size, to successful completion, the capsulorhexis is composed of many separate components. Our instructors share their experience on how to perform and, more importantly, practice this essential part of phacoemulsi- fication. Sherleen Chen, M.D., and Roberto Pineda, M.D. Cataract tips from the teachers Sherleen Chen, M.D. Instructor in 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

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