Article
New IOL may reduce opacification
The design of a new accommodating IOL shows promise in reducing the capsular bag opacification that can occur following cataract surgery.
Take-home
The design of a new accommodating IOL shows promise in reducing the capsular bag opacification that can occur following cataract surgery.
Dr. Floyd
By Fred Gebhart; Reviewed by Anne Floyd, MD, MS
Salt Lake City-A new accommodating IOL design shows promise in reducing the capsular bag opacification that can occur following cataract surgery.
A large, fluid-filled lens with oversized haptics that almost completely fills the capsular bag showed little to no opacification in a rabbit model 6 weeks after surgery.
“One of the ultimate goals of IOL development is to design a lens that you can implant and does not require any further interventions,” said Anne Floyd, MD, MS, former ocular pathology and research fellow, John A. Moran Eye Center, University of Utah, Salt Lake City. “These early animal results are very promising in that regard.”
Dr. Floyd, now a resident at Banner Good Samaritan Medical Center, Phoenix, is lead author on one of the first studies to be published on the FluidVision Lens, developed by PowerVision.
“One of the most common postoperative complications of cataract surgery is the development of ACO or PCO,” Dr. Floyd said. “Yes, you can use a YAG laser to perform a capsulotomy on the capsule bag to remove overgrowth and open up the window again, but that is one more procedure the patient has to undergo. And it opens up the posterior capsule, something you try to avoid doing because that is one of the barriers between the anterior and posterior segments. If you can avoid opacification in the first place, you don’t have to worry about compromising the integrity of that posterior capsule.”
The FluidVision Lens is a hydrophobic acrylic accommodating IOL with oversized haptics. The hollow optic is filled with index-matched silicone oil. Oil flows back and forth between the haptics and the optic, changing the curvature of the optic and the power of the correction. The entire device is about a quarter larger than the typical accommodating IOL. The theory is that a larger device that more completely fills and expands the capsular bag is less likely to develop ACO/PCO compared with current devices.
Researchers at Moran implanted the FluidVision lens in 1 eye of 6 New Zealand rabbits. The contralateral eye received a single-piece hydrophobic acrylic PCIOL (AcrySof SA60AT, Alcon Laboratories) that is commercially available.
The primary outcome was a comparison of ACO/PCO development between the two types of lenses. All 12 eyes were examined weekly by slit lamp from postoperative day 1 through week 6. At 6 weeks, the globes were enucleated and examined. Capsular bag opacification was additionally evaluated and scored from the posterior aspect using the Miyake-Apple view and the eyes were processed for complete histopathologic evaluation.
At the 6-week slit lamp exam, the control eyes showed a posterior capsule opacification mean score of 3.0 compared with 0.5 for the FluidVision eyes (p = 0.001).
The Miyake-Apple view showed visible opacification on the control eyes but not on the FluidVision eyes.
The control eyes had a mean central PCO score of 3.0 compared with 0.0 for the FluidVision eyes (p = 0.001), a peripheral PCO score of 3.5 compared with 0.7 for FluidVision eyes (p = 0.0006) and Soemmering’s Ring score of 7.0 compared with 2.3 for FluidVision eyes (p = 0.01).
“This design was born out of studies suggesting that a more open or a more expanded capsular bag may lead to prevention of PCO,” Dr. Floyd said. “In regard to ACO formation, previous reports described ACO and fibrosis occurring in areas where the anterior capsule comes into contact with the IOL optic. If you prevent that contact, the thinking goes, you might prevent or reduce the anterior capsule opacification.”
The results of this study tend to support the new design, Dr. Floyd said.
The anterior capsule remained remarkably clear throughout the study in the FluidVision eyes. The anterior capsule at and around the capsulorhexis edge was held at a distance from the anterior surface of the IOL by the oversized haptics and was almost completely devoid of fibrosis. These results are all the more important since the absence of a capsular reaction support the idea that the lens, which is sensitive to the capsular geometry, will remain stable and that the accommodative function of the lens will not be affected.
“This appears to be an expansive effect,” Dr. Floyd said. “The leading theory is that PCO prevention works by mechanical compression of the bag, which inhibits epithelial cells from migrating or infiltrating around the posterior portion of the capsule.”
Stretching of the bag at the equatorial region may help to maintain the overall contour of the bag and physically limit the extension of the lens epithelial cells toward the central region of the posterior capsule.
“We need to see further research on the mechanical compression and stretching provided by this device to more fully understand the mechanisms by which it seems to prevent or inhibit PCO,” she said.
In addition to ongoing animal studies, there is a preliminary program of clinical studies designed to evaluate the accommodative performance and power change of this new lens design, Dr. Floyd added.
Early results from a current clinical study under way appear to confirm the stability of this lens in the capsule, a point also demonstrated based on 1-year follow-up of a similar, prior generation lens.
Anne Floyd, MD, MS
Dr. Floyd had no financial disclosures related to the device.
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