EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/357599
On the negative side, Dr. Malyugin noted OVDs do not last very long in the anterior chamber, rendering them unreliable for the full procedure unless they're helped with a ring or other pupil expansion device. "Or you can reinject the OVD several times during the surgery," he said. Dr. Miller said that when the patient is already on the table, "and you're already in the eye, then I would recommend more lidocaine to make sure the eye is fairly numb" before stretching, he said. "Be very gentle and do not suddenly stretch the iris." Dr. Malyugin said when us- ing iris expanders, "always inject lidocaine intracamerally" to decrease sensations of the patient. Dr. Miller puts the distal scroll of the Malyugin device in first, rocks the two side rings in, and "just injects" the last ring into the eye. "Then we'll take the ring manipula- tor and hook the last ring over the pupil margin," he said. If the pupil gets pushed to one side, Dr. Miller said an advantage of the Malyugin ring design allows surgeons to recenter the pupil. Dr. Malyugin advises surgeons "not to overfill" the chamber be- cause that presses the iris toward the anterior capsule. Positioning the injector tip close to the iris margins can be helpful to engage the first scroll as well, he said, and recom- mends slowly withdrawing the inserter back as that makes it easier to get the ring out. If the pupil "is very small and there are posterior synechiae present, before implant- ing the ring I like to separate these adhesions with a spatula or some other instrument to free the edge of the pupil so it will be much easier to manipulate the ring in place," he added. Dr. Fladen cautioned to be wary of not stripping Descemet's mem- brane. He uses a thicker OVD to avoid the issue. In cases of "very strong and fibrotic pupils (usually due to uveitis)," posterior synechiae can be complicated by retropupillary membranes and stretching the pupil before implanting a ring can help, Dr. Malyugin said. Dr. Miller said extracting these devices may be more difficult than inserting them. With the Malyugin ring, for instance, the "trick" is to release the distal scroll first, as popu- larized by Thomas Oetting, MD. "Reach across the eye to take that one off first," he said. "Push Russia, noting these are most effective in patients with small pupils associated with weakened zonules. "In those cases, I will recommend using the hooks for the purpose of supporting the bag and expanding the pupil at the same time." He prefers special capsular hooks (by MicroSurgical Technology, Redmond, Wash.) with elongated portions; instead of "resting in the capsulorhexis, they help with capsular support. This is very important because when there's too much pressure on the edge of the capsulorhexis, the capsulorhexis can break and create radial tear," Dr. Malyugin said. Although there are several devices capable of expanding the pupil, in the U.S. the Malyugin ring (MicroSurgical Technology) is considered a favorite. Others include the Graether Pupil Expander (EagleVision, Memphis, Tenn.), Morcher Pupil Dilator (Morcher, Stuttgart, Germany), the Oasis Iris Expander (Oasis Medical, Glendora, Calif.), and the Perfect Pupil (Milvella, North Sydney, Australia). Dr. Fladen said the groove in the Graether device was "a little cumber- some," and he prefers the taper-foot concept of the Malyugin ring. Dr. Malyugin said one advan- tage of the ring is its 8 points of iris fixation. The increased number of fixation points means surgeons won't "over-stress or over-stretch the pupil as tends to happen with iris hooks," he said. The latter creates sphincter tears and causes atonic pupil postoperatively that may occur in up to 15% to 20% of cases when the iris hooks are used, he added. Dr. Miller said identifying those patients with small pupils in the office (during routine dilations) is relatively easy, so he has a "rela- tively low threshold for doing an injection-type of anesthetic rather than a topical anesthetic. Placing these rings or hooks under topical anesthesia is just a little bit more challenging because they feel the stretch." Surgical techniques Stabilizing the pupil (and possibly expanding it) with intracameral phenylephrine or epinephrine is rec- ommended first, Dr. Malyugin said. During the cataract surgery itself, he recommends using a "highly viscous OVD; many surgeons prefer using a viscoadaptive OVD like Healon5 [Abbott Medical Optics, Santa Ana, Calif.]," he said. The benefits include deepening the anterior chamber, which also helps expand the pupil. the distal portion all the way into the opposite corner of the anterior chamber. That pushes the entire ring a little farther away from the incision, which makes it so much easier to grab. Then you release the proximal loop. You don't have to release the other two. Go in with the insertion device and hook the proximal loop," he said. Other possibilities There are other expanders in development, including the APX (Assia Pupil Expander, APX Ophthalmology Ltd., Haifa, Israel) and the disposable square and hexagonal Bhattacharjee pupil expansion rings (Madhu Instru- ments, New Delhi, India). Dr. Malyugin called the APX "a great idea" as it helps to reduce the number of paracenteses needed to insert the iris hooks from 4 to 2. The APX achieves pupil expan- sion by using two devices inserted through two 19G (1.1 mm) sideport incisions located opposite to each other. The curved distal tips are inserted behind the pupil and when the forceps are released, the device opens, developer Ehud Assia, MD, wrote in EyeWorld last year. 1 "The APX goes into a slightly enlarged paracentesis," Dr. Miller said, which may explain the reduced number needed. The Bhattacharjee device is a ring made from 5-0 black monofila- ment polyamide, with the end butt joined with glue, said Suven Bhattacharjee, MS, DO, DNB, in his technique article. 2 The device has been designed in both square and hexagonal versions ranging in size from 6.0 mm to 7.0 mm; the size recommended for use is depen- dent upon the white-to-white corne- al diameter. According to the study results, the device can be inserted in incisions as small as 0.9 mm. EW References 1. Assia, E. APX: Novel device for pupil expansion. EyeWorld. 2013 July:49–50. 2. Bhattacharjee S. Pupil-expansion ring implantation through a 0.9 mm incision. J Cataract Refract Surg. 2014;40:1061–1067. Editors' note: Dr. Malyugin has financial interests with MicroSurgical Technology. Drs. Miller and Fladen have no financial interests related to their comments. Contact information Fladen: tfladen@fladeneyecenter.com Malyugin: boris.malyugin@gmail.com Miller: kmiller@ucla.edu August 2014 © 2014 Novartis 2/14 VRN14003JAD-B PI IMPORTANT SAFET Y INFORMATION FOR THE VERION™ REFERENCE UNIT AND VERION™ DIGITAL MARKER CAUTION: Federal (USA) law restricts this device to sale by, or on the order of, a physician. INTENDED USES: The VERION ™ Reference Unit is a preoperative measurement device that captures and utilizes a high-resolution reference image of a patient's eye in order to determine the radii and corneal curvature of steep and flat axes, limbal position and diameter, pupil position and diameter, and corneal reflex position. In addition, the VERION ™ Reference Unit provides preoperative surgical planning functions that utilize the reference image and preoperative measurements to assist with planning cataract surgical procedures, including the number and location of incisions and the appropriate intraocular lens using existing formulas. The VERION ™ Reference Unit also supports the export of the high-resolution reference image, preoperative measurement data, and surgical plans for use with the VERION ™ Digital Marker and other compatible devices through the use of a USB memory stick. The VERION ™ Digital Marker links to compatible surgical microscopes to display concurrently the reference and microscope images, allowing the surgeon to account for lateral and rotational eye movements. In addition, the planned capsulorhexis position and radius, IOL positioning, and implantation axis from the VERION ™ Reference Unit surgical plan can be overlaid on a computer screen or the physician's microscope view. CONTRAINDICATIONS: The following conditions may affect the accuracy of surgical plans prepared with the VERION ™ Reference Unit: a pseudophakic eye, eye fixation problems, a non-intact cornea, or an irregular cornea. In addition, patients should refrain from wearing contact lenses during the reference measurement as this may interfere with the accuracy of the measurements. Only trained personnel familiar with the process of IOL power calculation and astigmatism correction planning should use the VERION ™ Reference Unit. Poor quality or inadequate biometer measurements will affect the accuracy of surgical plans prepared with the VERION ™ Reference Unit. The following contraindications may affect the proper functioning of the VERION ™ Digital Marker: changes in a patient's eye between preoperative measurement and surgery, an irregular elliptic limbus (e.g., due to eye fixation during surgery, and bleeding or bloated conjunctiva due to anesthesia). In addition, the use of eye drops that constrict sclera vessels before or during surgery should be avoided. WARNINGS: Only properly trained personnel should operate the VERION ™ Reference Unit and VERION ™ Digital Marker. Only use the provided medical power supplies and data communication cable. The power supplies for the VERION ™ Reference Unit and the VERION ™ Digital Marker must be uninterruptible. Do not use these devices in combination with an extension cord. Do not cover any of the component devices while turned on. Only use a VERION ™ USB stick to transfer data. The VERION ™ USB stick should only be connected to the VERION ™ Reference Unit, the VERION ™ Digital Marker, and other compatible devices. Do not disconnect the VERION ™ USB stick from the VERION ™ Reference Unit during shutdown of the system. The VERION ™ Reference Unit uses infrared light. Unless necessary, medical personnel and patients should avoid direct eye exposure to the emitted or reflected beam. PRECAUTIONS: To ensure the accuracy of VERION ™ Reference Unit measurements, device calibration and the reference measurement should be conducted in dimmed ambient light conditions. Only use the VERION ™ Digital Marker in conjunction with compatible surgical microscopes. ATTENTION: Refer to the user manuals for the VERION ™ Reference Unit and the VERION ™ Digital Marker for a complete description of proper use and maintenance of these devices, as well as a complete list of contraindications, warnings and precautions. Hooks and expanders continued from page 20