March 2010

 

CATARACT /IOL

 

Sublux options grow


by Lisa Arbisser, M.D.

 

Some of the most difficult and challenging cases in cataract surgery include patients with subluxed crystalline lenses or severely weakened zonules. These can result from genetic disorders such as Marfan syndrome and pseudoexfoliation or from trauma. The increasing surgical options for approaching these cases utilizing capsular bag prosthetic devices improves our ability to provide capsular bag IOL placement with good centration. In this month’s column, Lisa Arbisser, M.D., reviews some of the old and new options available to deal with these challenging cases.

Richard Hoffman, M.D., Column Editor

 

An increasing number of variations on capsular tension rings will give cataract surgeons more choices in dealing with subluxed crystalline lenses

Post-op inferior subluxation of capsular bag-IOL-CTR complex.

Source: Ike Ahmed, M.D.

Surgical outcome following implantation of a Cionni ring—one of many highly recommended pieces—which was suture fixated to the sclera inferonasally. Source: Samuel Masket, M.D.

StabilEyes Source: Abbott Medical Optics

Although the number of patients displaying subluxed crystalline lenses due to weakened or missing zonules may be steady, the options for cataract surgeons to address this situation are growing.

Many surgeons now have experience with the standard capsular tension ring, commonly utilized in cases of zonular weakness caused by pseudoexfoliation and traumatic lens displacement. Many leading cataract surgeons now advise others to keep on hand for all cataract surgeries one of the two types of CTRs with U.S. approval: the Reform ring (Morcher GmbH, Stuttgart, Germany) and the StabilEyes ring (Abbott Medical Optics, Santa Ana, Calif.) which are not appropriate in all cases of zonular loss. Standard CTRs do not provide adequate centration of the capsular bag when the zonulopathy is extensive and the lens is severely subluxed.

I commonly use the Cionni modified Morcher ring, which has a fixation hook that can be sutured to the scleral wall without piercing the capsular bag. However this device is not easy to insert prior to the removal of the lens when it sometimes is most needed for stabilization.

The advantages of the Cionni ring include the provision of full circular support, while a smaller capsular tension segment only supports a limited area of damaged zonules. Sometimes combining a regular CTR and a ring segment works well.

Among the emerging segment options is the Ahmed CTS (Morcher), which recently received Food and Drug Administration approval. This partial ring has a fixation hook and can be placed after anterior capsulotomy and temporarily fixated to the limbus with an inverted iris retractor. It can also be permanently fixated to the sclera with a suture.

“It serves and functions much like a retraction device but it is also designed to be suture fixated to the sclera as a long-term stabilization device,” said Iqbal (Ike) K. Ahmed, M.D., assistant professor, University of Toronto, Toronto, and clinical assistant professor, University of Utah, Salt Lake City, who developed the segment.

He notes that in cases of profound zonular insufficiency the use of multiple Ahmed segments can provide intra-operative support, as well as providing long-term post-op centration of an IOL within the capsular bag.

Another advantage of the Ahmed segment over the Cionni device is that it does not require surgeons to thread it all the way around the capsular bag fornix. “It’s easier to get in and manipulate and to get back out again if you decide you don’t want it in there.” The CTS does not require use of a dialing technique, which can transmit more destabilizing force to the zonular apparatus. Instead it is designed to slide into the capsular bag with minimal trauma after the capsulorrhexis and placed in the area of zonular weakness. This allows CTS use early in a case before removal of the cataract.

The Ahmed device also is believed to better avoid pigment dispersion, which is rare but can develop with the Cionni ring if it ends up on top of the anterior capsule.

Another new option is the Capsular Anchor (Hanita Lenses, Kibbutz Hanita, Israel), which was presented at the American Academy of Ophthalmology’s 2007 Annual Meeting in New Orleans. Developed by Ehud I. Assia, M.D., chairman of ophthalmology, Meir Medical Center, Kfar-Saba, Israel, the anchor works like a paper clip, with a central rod that is placed in front of the capsule, and two lateral arms inserted through the capsulorhexis and placed behind the anterior capsule. The surgeon can then loop a suture through the device to anchor it to the eye.

Dr. Ahmed noted that the growing number of surgical options should give more cataract surgeons the confidence to address zonular problems instead of the previous practice of referring such patients to vitreal-retinal specialists. These emerging capsular tension devices can help reduce the risk of intra-op and post-op complications and improve patient outcomes. In cases of zonular weakness, the use of capsular tension devices can ensure both safe removal of the crystalline lens as well as adequate and stable placement of the IOL for long term centration and stability.

Editors’ note: Dr. Arbisser has financial interests with Alcon (Fort Worth, Texas). Dr. Ahmed has no financial interests related to his comments.

Contact information

Arbisser: 563-323-2020, drlisa@arbisser.com

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