Eyeworld

I CHALLENGING CATARACT CASES SEPTEMBER 2019 | EYEWORLD | 61 can become dislocated and can sunset out of the visual axis and even into the mid-vitreous. Placing the patient in a supine position in the examination room can help to highlight this issue," he said. Preserve the zonules Preserving the integrity of the zonular fibers is vital. The zonular attachments to the lens cap- sule not only provide stability during cataract surgery, they also directly affect the long-term visual outcome of the procedure. When the zonules are compromised, surgery is adapted to preserve the remaining zonules as best as possible and to ensure stability of the intraocu- lar lens implant. According to Dr. Miller, the extent of zonular laxity or dehiscence can at times be obvious. More often, however, the pathology is subtle, and therefore knowing the indicators of zonular weakness is paramount. "Look for iridodonesis and phacodonesis. Often, the lens will be deep to the iris and you may see vitreous in the anterior chamber. In these cases, the vit- reous needs to be removed completely from the anterior chamber, the capsular bag stabilized, and the cataract gently removed. In all cases, I will use a capsular tension ring to reduce further damage to the zonular fibers," he said. Missing zonules of one or two clock hours do not present a dire situation, however, Dr. Miller always places a capsular tension ring (CTR) to support the capsule in that area and keep it from folding in on itself. As a gener- al 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 tension segments or modified 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 continued on page 62 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 advan- tages for iris or scleral fixation in the months and years that follow, if the lens implant decides to decenter or dislocate," he said. Dr. Miller implements an injector for cap- sular tension ring implantation. In the absence of a capsule retractor to stabilize the capsu- lar bag, he injects toward the area of zonular dehiscence, laying the ring out for the first 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 vitrec- tomy 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. Dev- gan. "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 Contact information Miller: miller@jsei.ucla.edu Devgan: devgan@gmail.com At a glance • The cataract surgeon needs to adapt his or her approach to cataract surgery based on the degree of zonulopathy present in the eye. • Zonulopathy caused by trauma is generally segmental while diffuse zonulopathy is asso- ciated with a variety disease states. • The surgeon's main goal is to preserve the integrity of the remaining zonular fibers, which stabilize the lens cap- sule and affect the long-term visual outcomes. About the doctors Uday Devgan, MD Devgan Eye Surgery Los Angeles Kevin M. Miller, MD Kolokotrones Chair in Ophthalmology David Geffen School of Medicine at University of California, Los Angeles Relevant financial interests Miller: None Devgan: CataractCoach.com

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