EyeWorld Asia-Pacific December 2019 Issue

FEATURE 18 EWAP DECEMBER 2019 tension ring (CTR) to support the capsule in that area and keep it from folding in on itself. As a general rule, he places CTRs in all eyes that have obvious zonular problems, whether sectoral or diffuse. In addition to a CTR, depending on capsule centration, he uses capsule ÌiÃ Ãi}iÌÃ À `wi` Cionni tension rings to secure the capsule bag to the sclera when necessary. “It will help those eyes with sectoral zonular loss, like from trauma,” Dr. Miller said. “There is also the trauma of the surgery itself and what that does to the zonules, but there is the postoperative effect of the capsule shrink wrapping around the implant. If it shrinks aggressively, it will tear the zonules, so I insert a CTR to reduce additional stress on the zonules. But more importantly, the CTR offers advantages for ÀÃ À ÃViÀ> wÝ>Ì Ìi months and years that follow, if the lens implant decides to decenter or dislocate,” he said. Dr. Miller implements an injector for capsular tension ring implantation. In the absence of a capsule retractor to stabilize the capsular bag, he injects toward the area of zonular dehiscence, >Þ} Ìi À} ÕÌ vÀ Ìi wÀÃÌ 180 degrees and injecting it for the rest. A CTR will stretch the bag in cases of focal zonular dialysis, stretch the equator of the capsule bag to resist the centripetal contraction that typically follows surgery, potentially reduce the event of late decentrations and dislocations, and allow easier management of late capsular problems, he noted. When zonular support is lost and the eye is essentially aphakic, the surgeon is constrained to abandon the capsule and look for other solutions. Dr. Miller thinks that anticipating this situation lets the surgeon prepare for a more complicated surgery, including selection of a three-piece or anterior chamber IOL, as well as an appropriate choice of anesthesia. These surgeries take longer, such as for scleral tunnel procedures, and are associated with increased stress in older patients. Oftentimes, a vitrectomy and the use of an anterior chamber lens serves an older patient best without overly prolonging surgery. Intraoperative pearls Zonular weakness may not always be obvious. Knowing what to look for intraoperatively can make all the difference, according to Dr. Devgan. “During cataract surgery, if the zonular structures are intact and normal, the anterior lens capsule should be taut, like the head of a drum, especially after instillation of viscoelastic. When we poke into the anterior lens capsule with our forceps or a cystotome for the creation of capsulorhexis, it should puncture easily. But if we see radial wrinkles from our attempted puncture and the anterior capsule is not tightly stretched, this indicates zonular >ÝÌÞ° /Ã Ã `vwVÕÌ Ì «ÕVÌÕÀi I n addition to the signs that have been described, any male patient presenting with acute angle closure glaucoma should have an assessment of the zonular status before surgery. Ultrasound biomicroscopy (UBM) is able to determine the extent and severity of zonular loss and demonstrate vitreous herniation. Performed with the patient supine, it images the resting lens position to be expected during surgery. Another important test is the endothelial cell count, which may be unexpectedly low. In cases of severe zonulysis, in addition to having a single piece hydrophobic acrylic intraocular lens, capsular tension devices and hooks available, a 3-piece IOL or iris clip IOL should also be on standby. Intravenous mannitol reduces the risk of vitreous presentation and provides room for instrumentation in a shallow anterior chamber. I prefer femtosecond laser capsulotomy, as it ensures that the capsulotomy is round, intact, appropriately sized and centered on the scanned capsular bag. Lens fragmentation is helpful when the nucleus is dense as it minimizes excessive capsular bag stress during nuclear disassembly. Avoid capsule stains if possible to prevent a dye-stained vitreous. If laser is unavailable, capsulorhexis can be initiated with a 27-G needle. Microinstruments should be used to prevent escape of viscoelastic during the procedure. An iris hook can provide capsular support and countertraction during capsulorhexis. Alternatively, bimanual capsulorhexis in severe zonulysis is effective. I prefer to insert a capsular tension ring (CTR) before removal of the nucleus. Perform cortical cleaving viscodissection up to the equator before CTR insertion to avoid trapping cortex. The CTR can be inserted in either direction because the lens holds the capsular bag open and engaging or puncturing the capsular bag becomes unlikely. In severe zonulysis, insert one capsular bag hook to support the lens before injecting the CTR away from the hook. Capsular hooks support the bag at the equator and do not threaten the integrity of the capsulorhexis, sealing the gap between the anterior chamber and vitreous cavity. *>ViÕÃwV>Ì v Ìi iÃ V> Ìi «ÀVii` Ã>viÞ° If the IOL is decentered or moves when the eye is shaken, the V>«ÃÕ>À L>} ÃÕ` Li ÃÌ>Lâi` LÞ wÝ>Ì v > V>«ÃÕ>À ÌiÃ segment or two to the sclera. If capsular support devices are not available, I would prefer suturing a 3-piece IOL in the sulcus to the iris over placing it in the capsular bag as described. 'FKVQTUo PQVG &T %JGG FGENCTGF PQ TGNGXCPV ƂPCPEKCN KPVGTGUVU Chee Soon Phaik, MD Senior Consultant, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 chee.soon.phaik@singhealth.com.sg ASIA-PACIFIC PERSPECTIVES and is an important warning sign that zonular weakness may pose challenges and induce complications during cataract surgery,” he said. Dr. Devgan makes a generous capsulorhexis between 5 and 5.5 mm in diameter and avoids placing stress on the capsular bag during nucleus division. He recommended caution during cortex removal to avoid further zonular compromise and careful IOL selection and placement to