The mini-cap is an exciting new procedure that uses a smaller incision than MSICS without the need for phacoemusification. The miLOOP is used to bifurcate the crystalline lens without putting energy in the eye.
Lecturer: Barbara C. Erny, MD, Medical Liaison for International Programs, ASCRS Foundation, USA
DR ERNY: Hello. I’m Dr. Barbara Erny, and I’m here today to talk to you about the Mini-cap, an exciting new technique for cataract surgery. I’m an ophthalmologist and I work with the American Society of Cataract and Refractive Surgery Foundation. The Mini-cap is a new technique that uses an instrument called the miLOOP to have an energy-free disassembly of the crystalline lens into two pieces. This allows a safer surgery than phacoemulsification, using a smaller incision size than with SICS. The miLOOP was developed into a snare-like instrument to cut the nucleus. It’s extremely sharp and able to cut even rock hard nuclei into pieces. The loop is made of nitinol, which is a proprietary metal, and the blade inside the snare is sharp enough to cut through even the hardest nuclei. As you can see, the loop is shaped like the human crystalline lens. The Mini-cap is a new surgical technique, and in this slideshow, I’m going to explain how to do it. This assumes a right-handed surgeon and a temporal approach. Of course, you can do it if you’re left-handed, but you’ll need to develop your own approach on how to use your dominant hand. The wound construction of the Mini-cap is very similar to SICS. Starting 2 millimeters behind the limbus, you can make a smile, frown, or straight incision with your blade, and then do your normal scleral tunnel. However, you only have to go to a 6 millimeter internal scleral pocket. Make your paracentesis on the right and/or the left, depending on your comfort, using a second instrument. Stain the capsule with Trypan blue, and use adrenaline as needed for a small pupil. Then add your viscoelastic. Make about a 2.5 millimeter keratome incision through your scleral tunnel. The capsulotomy can be done either as a can opener capsulotomy or a continuous curvilinear capsulorrhexis. If doing a capsulorrhexis, make it slightly larger than you do for phacoemulsification, or approximately 6 millimeters. If doing a can opener, make very small cuts and approximately 5.5 millimeter diameter. Perform gentle hydrodissection under the left side of the capsule. The reason you want to do it on the left is in order to not obscure the view of the right side of the capsule. You just have to do enough hydrodissection to have a lens rock or move a couple of clock hours. Do not hydrodissect it too much, or if the lens is very loose, it makes it very difficult to cut with the miLOOP. Now add a small amount of viscoelastic under the right side of the capsule edge, in order to lift it away from the lens and give you a clear view between the capsule and crystalline lens. Now you can get your miLOOP and inspect it under the microscope. You want to make sure that you can adjust the finger lever and that it is flowing smoothly. Also inspect the loop itself under the microscope to make sure there are no burrs or bends or any issues with the loop or with deploying the loop using your lever. Now retract the miLOOP to the neutral position, which is the first position where the lever easily stops at the end of the track. After that, there is another position where you have to forcefully pull the lever back to the hard stop. The finger button should be, at this point, to the left side of the handle, so that the miLOOP is facing to the right. The loop should always be on the right when you’re entering into the anterior chamber or exiting. Now, you must ensure that the patient does not move throughout the whole miLOOP maneuver. This is very important, because the miLOOP will be deployed around the crystalline lens, and there’s no way to safely pull it out of the eye if the patient moves. In order to insert the miLOOP properly into the eye, make sure that your loop is to the right. Have the lever pulled back at least to the neutral position, or even farther into the hard stop second position. It’s easier to get the miLOOP through any wound if you enter the long ways, and you can use one or both hands to stabilize the miLOOP. You should definitely practice using the miLOOP inside of the eye in order to be comfortable with your technique. Many surgeons use one hand or both hands, use their index finger or thumb, and there are many ways to use the miLOOP to your comfort level. Now, when you insert the miLOOP, again make sure that the cannula is going straight in through the keratome wound and that the loop is facing to the right. The black mark that is etched onto the cannula should be about 2 millimeters behind the limbus when you deploy the loop. This is because the loop itself was made to be able to wrap around the lens without the tip of the miLOOP being all the way to the center of the eye. The lever at this point is 90 degrees to the left side of the handle, because your loop is on the right side of the handle. Now, ensure that you are under the capsule edge. Of course, this is the most important point, because if your loop is over the capsule edge, you will end up cutting the zonules. As you deploy the loop, watch carefully — and this is where your Trypan blue comes in handy — to make sure that the loop continuously opens under the capsule edge. While you’re pushing the lever forward, you’ll see the loop deploy, and the miLOOP will start to curve around the lens on its own and dissect the cortex, even though you haven’t twisted your hand. Now you will rotate the miLOOP. Once the loop is fully deployed, you’ll feel a hard stop of the lever. This is when the lever is all the way to the front of the miLOOP. Now you know it’s safe to begin twisting your hand clockwise in order to get the loop to surround the lens and start to curve around it. The loop is going to trail your hand rotation. Watch the loop go past the midline if you have a red reflex. It’s good to practice on cases when you’re new that have a red reflex, so you can see where the loop is under the lens. Once you’ve passed the midpoint, the loop will lag for a few seconds behind your hand. You do want to go past the midpoint in order to dissect more cortex. Then you’ll turn your hand back counterclockwise, in order to get the bottom of the loop exactly perpendicular to the lens. Now the finger lever should be at the top position on the handle, parallel to the plane of the cornea. Now for the chopping maneuver. Move the cannula forward, so that the tip of the cannula is in the center of the lens and the black line is at the limbus. Now take your finger on the lever and pull the lever all the way back past neutral and to the hard stop. While you’re doing this, the lens may flip out of the capsular bag, which looks scary, but is actually a good thing, because it allows your pieces to come up out of the bag and make it easier to remove them after they’re chopped. Once the lever is retracted fully, you can twist your wrist again to move the lever and move the loop so the loop is now to the right, again, of your anterior chamber. You may need a second instrument to split the halves of the lens and help you to remove the loop. The loop now, still fully retracted, should be lifted over the lens and facing to the right, as it was when you entered the eye. As you lift it above the lens and make sure you’re above the capsule edges, you can retract and pull the loop out of your incision, preferably the long way, so that it doesn’t tear your incision. Now, the removal of the loop should be done just as you did the insertion. The loop is on the right. Then, as you pull out, you move your arm, so the loop will face the long ways through your wound. Now to open the wound. Before you open the wound, it’s helpful to manipulate the lens halves so that at least one of them is up out of the capsular bag and oriented longways, to come through the scleral incision easier. Once you have the lens pieces manipulated, you can open the wound to 6 millimeters internally. This is for insertion of a rigid IOL. Now, the removal of the heminuclei can be done in a variety of ways. The easiest way I’ve found is to use a 4 millimeter irrigating vectis. However, depending on your comfort level and the situation at hand, you can use a non-irrigating vectis, fishhook technique, viscoelastic technique, or using your Simcoe cannula. Add more viscoelastic if necessary to manipulate the second half of the lens into the position easiest to remove it from the eye. Now you can finish your case normally, do your cortical clean-up, your lens placement, viscoelastic removal, secure your wound, use a drop of Betadine, your normal antibiotics, and patch, if needed, for the type of anesthesia you’ve used. The video will show a very similar procedure to SICS, making a conjunctival peritomy and a 6 millimeter scleral incision. That incision will be tunneled to only 6 millimeters internally, as you can see now at the start of the video. Once you’ve made your scleral tunnel, you’ll enter with your paracentesis, which you can do on one or both sides. Now use Trypan blue, which will stain your capsule edge and make it easier to see once you’ve done your rhexis. If your pupil is small, you can also add adrenaline. Now remove your Trypan and viscoelastic before entering the wound with your keratome blade. Now you can either do a 6 millimeter capsulorrhexis or a can opener with very small cuts and about a 5.5 millimeter diameter. In this case, the surgeon is doing a large capsulorrhexis. Now you want to hydrodissect under the left side of the capsule edge and just rock or gently move the lens a couple of clock hours and don’t have it be totally spinning in the bag. Add viscoelastic under the right side of your capsule edge. Now inspect your miLOOP. Enter the eye. Keep the miLOOP to the right side of the lens. You can now deploy the lever of the miLOOP, pushing it forward until you feel the hard stop. This will occur once the loop is fully deployed. Before you even turn your wrist, you’ll see that the loop looks like it’s starting to curve around the lens. That’s normal. Now you can start to twist your lens clockwise to the right, so that the loop starts to go around the lens. The loop will trail your hand movement, and if you have a red reflex, you’ll be able to see that the loop is coming around, and you’ll go past the midline to the other side of the lens, to cut the cortical material. Now bring your loop back to center, so it exactly under the top loop, and make sure your handle and lever is perpendicular to the eye. Now make a smooth, continuous cut by pulling the lever all the way to the hard stop, and it normal to see the lens flip out of the capsular bag. After you’ve pulled it all the way to the hard stop, keep it at the hard stop. Bring your loop up above the cut lens, above your capsule edge, and remove it from the eye. Now you can separate the halves. You may have needed a second instrument to help separate them when you made the cut. Line up at least one of the halves out of the capsular bag and longways with your wound. This will help you when you expand your wound and try to remove the pieces. Now open your wound to the 6 millimeter internal diameter. Use an irrigating 4 millimeter vectis or any technique you’re used to using to remove the lens. After removing one half, you may need to add more viscoelastic and manipulate the second half up out of the bag and orient it so it’s easiest to remove. Here again an irrigating vectis is being used to remove the lens piece. Now you can perform your normal cortical clean-up. Add your viscoelastic so that you can insert, in this case, a rigid PMMA lens. Remove your viscoelastic normally. And then you’re gonna finish your case with closing your conjunctiva, adding your antibiotics, Betadine, and patch as needed, after you have secured your wound. This concludes the video for the Mini-cap technique. Now to review the steps for learning. Do a normal temporal peritomy and 6 millimeter scleral incision, 2 millimeters behind the limbus, as you would for SICS. However, internally you need to only extend your tunnel to 6 millimeters wide. Do a paracentesis on the left and right as desired. Use Trypan blue to stain your capsule. Adrenaline is needed for a small pupil. And viscoelastic. Do a stab entry to your scleral tunnel with a keratome blade. Make either a can opener capsulotomy or a continuous curvilinear capsulorrhexis approximately 6 millimeters in diameter. Hydrodissect under the left side of the capsule edge, until just your lens rocks or moves a couple of clock hours. Add viscoelastic under the right edge of your capsule to separate it from the lens. Now use your miLOOP to cut the lens in half. Remove the halves from the eye after opening the wound. Do your cortical clean-up, lens insertion, and finish your case normally. The Mini-cap offers another alternative to phacoemulsification for paying patients in developing countries. It is a safer and easier technique to learn than phacoemulsification. However, it is distinguished from SICS by using a smaller incision. Thank you for your attention.
July 30, 2019