Cataract
June 2022
by Liz Hillman
Editorial Co-Director
Lens dislocation is a spectrum. It can be anywhere from a small amount of decentration to a complete dislocation with the IOL-capsular bag complex sinking into the posterior chamber or falling into the vitreous. It can occur in the immediate postoperative period or “late,” which is considered anything after 3 months postop, according to Nick Mamalis, MD. For the most part, Dr. Mamalis said, spontaneous late IOL dislocation occurs about 10 years postop.
In this article, EyeWorld looks at late dislocations that don’t appear to be related to surgical complications. Late dislocations have different etiologies. Trauma can dislocate the lens-bag complex, but the physicians EyeWorld spoke to, Dr. Mamalis and Steven Safran, MD, focused on spontaneous late dislocations.
Source: Steven Safran, MD
Why lens-bag complexes dislocate
The most common reason Dr. Mamalis and Dr. Safran cited for spontaneous lens-bag dislocations is pseudoexfoliation syndrome. Dr. Mamalis said the Ophthalmic Pathology Laboratory at the John A. Moran Eye Center has conducted studies on dislocated IOLs and capsular bags that have been sent to it over the years, finding that pseudoexfoliation (or exfoliation syndrome) is the most common factor that seems to be associated with late IOL dislocations.
“We’re finding that exfoliation syndrome might be related to up to two-thirds of these,” he said.
Dr. Mamalis said that during surgery the signs of pseudoexfoliation can be subtle and easy to miss. He said that exfoliation syndrome seems to pose a “triple threat” to the zonules. Material from exfoliation deposits where the zonules attach to the capsular bag, where the zonules insert to the ciliary body, and on the zonules themselves.
“All of this adds up to diffuse weak zonules that can lead to spontaneous dislocation,” Dr. Mamalis said.
Dr. Mamalis and Dr. Safran also said prior vitreoretinal surgery seems to be associated with late lens-bag dislocations.
“There’s something about the vitrectomy procedure where the gelatinous vitreous is replaced by fluid, and that can cause the zonules to stretch and put more stress on them,” Dr. Mamalis said, adding that about 20% of late dislocations have had vitrectomy.
Dr. Safran said that a lot of fibrosis of the capsular bag seems to be related to late dislocation as well. The fibrosis leads to matrix metalloproteinase production, which can dissolve the zonules over time.
On the flip side, some cases of dislocation have a complete lack of fibrosis; the capsules are completely clear and diaphanous. This condition has been coined “dead bag syndrome.” Dr. Mamalis was a co-author on a paper published earlier this year in the Journal of Cataract & Refractive Surgery that examined the clinical and histopathological findings of capsular bags and IOLs from dead bag syndrome cases.1
“These capsules were crystal clear, and when we look at them under pathological analysis, we found there was a splitting of the capsule,” Dr. Mamalis said. “There will be an absence of lens epithelial cells, absence of proliferative cortical material. In terms of why this is happening, at this point we can only speculate as to the real reason. … It’s known that the lens epithelial cells that normally reside even after cataract surgery in the capsular fornix have some factors that act to maintain the capsular bag. … In these cases, the lens epithelial cells are completely absent for reasons we don’t understand.”
Dr. Mamalis emphasized that while the capsular bag-IOL complex dislocates with dead bag syndrome, it is a different entity than late spontaneous lens dislocation.
Prevention and treatment
From a prevention standpoint, Dr. Safran said it’s important to do atraumatic surgery. He also said to clean out the bag well, removing epithelial cells that could lead to fibrotic contraction that pulls on zonules.
If there is evidence of pseudoexfoliation or weak zonules, he said it’s a good idea to place a capsular tension ring, which could give something to lasso onto later should it dislocate. Dr. Safran said he’ll place a capsular tension segment and suture to the sclera if things seem loose at the time of surgery.
“I’ll do that if I think it’s likely the patient will have a dislocation in their lifetime,” he said, adding, however, that if the patient’s expected lifespan isn’t long or if they’re not that active, he probably would not do this. “You don’t want to be doing unnecessary steps that could cause complications, especially if you’re not used to doing it. It could be fixed later by someone who is skilled at doing that.”
Dr. Mamalis shared a few possible preventative strategies as well. He said to make sure the capsulorhexis is an adequate size. This removes some lens epithelial cells, and he mentioned that some people advocate for polishing the capsule. If you start to see the capsulorhexis shrink over time (capsular phimosis), some suggest doing an anterior YAG capsulotomy with four small radial incisions 1–2 mm outward from the edge of the rhexis, relieving the phimosis that pulls on the zonules.
“[Another] thing physicians talk about is should we be putting a capsular tension ring in the bag to help prevent late postoperative dislocation? I don’t know the answer to that. We’d need to put that in a large number of patients, follow them for 10 years, and see what it does,” he said. “But I can say be vigilant in following [patients who have pseudoexfoliation or who’ve had vitrectomy]. If the IOL-capsular complex begins to dislocate, you want to recognize that early on when there is a chance to suture the complex to the ciliary sulcus.”
He said that in the laboratory, he has received spontaneously dislocated IOLs where there is a beautifully centered capsular tension ring within the capsular bag, but the complex still dislocated.
Another tactic, if there is known, diffuse zonulopathy, is to put the IOL in the sulcus and capture the optic in the capsulotomy, Dr. Mamalis said, noting that there are not studies to support that this prevents late dislocations.
When late lens-bag dislocation occurs, Dr. Safran said there are a number of ways to handle it, depending on the presentation and other factors. He said he would lasso the lens-bag complex under certain conditions: if the patient was happy with the lens before, if it was the right power and undamaged, etc. He will not scleral fixate hydrophilic acrylic lenses due to their propensity to calcify over time; he’ll take those out.
He would also take out lens-bag complexes that have a lot of Soemmering’s ring material because it’s pro-inflammatory. If the lens is sitting on the retina, if it’s a Crystalens (Bausch + Lomb), or a plate-haptic lens, he said he’ll usually take it out. He’ll also take out a dead bag, which he explained is so diaphanous it shreds if you try to do anything with it.
“The capsular bag itself has to have enough fibrosis to hold,” he said.
When it comes to putting in a new IOL, Dr. Safran will generally do the Yamane double- needle intrascleral haptic fixation technique. There are rarer indications where he’ll use GORE-TEX sutures.
While there are techniques to fix dislocated lens-bag complexes, Dr. Safran said they’re not things surgeons should “dabble in.”
“If you’re only going to do this once or twice a year, I wouldn’t mess around with it because there is a lot of potential to cause problems if you don’t do it correctly,” he said. “A lot of the ones referred to me are revisions of cases other people tried to do, and they’ve dug a deeper hole for the patient. … If it’s not something you plan on doing frequently or do on referral, consider referring to someone who does a lot of them.”
Dr. Safran said while patients might notice a change in their vision or a bobbing of the IOL, sometimes it’s the physician who notices the lens-bag complex is beginning to dislocate. If it’s not fully dislocated and not impacting the patient’s perception of their vision, it’s reasonable to wait to repair this until the patient becomes aware of symptoms or develops a problem related to the IOL dislocation.
“Ophthalmologists often think that there is an urgency to these procedures because the lens may dislocate posteriorly. However, it’s easier to justify surgical repair on a patient once they’ve developed symptoms related to the dislocation because they’re more accepting of having a surgical procedure and all that comes with it,” Dr. Safran said. “Also, there are excellent techniques for dealing with IOL bag complexes that dislocate posteriorly so really there is no urgency for these patients to have surgery unless they have a visual problem or uveitis-glaucoma-hyphema syndrome related to the IOL.”
Learn more about dead bag syndrome in this EyeWorld Online Exclusive.
About the physicians
Nick Mamalis, MD
Professor of Ophthalmology and Visual Sciences
John A. Moran Eye Center
University of Utah
Salt Lake City, Utah
Steven Safran, MD
Lawrenceville, New Jersey
Reference
- Culp C, et al. Clinical and histopathological findings in the dead bag syndrome. J Cataract Refract Surg. 2022;48:177–184.
Relevant disclosures
Mamalis: None
Safran: None
Contact
Mamalis: nick.mamalis@hsc.utah.edu
Safran: safran12@comcast.net
