April 2009

 

CATARACT / IOL

 

Avoiding posterior segment repercussions


by Matt Young EyeWorld Contributing Editor

   
The Crystalens 5.0 at 3 days (left) and 4 weeks (right) post-operatively. Retinal surgeons should be aware of the potential impact these lenses could have on the posterior segment Source: Jack Singer, M.D.

The benefits of presbyopia-correcting intraocular lenses (IOLs) are well established. The ability to see at distance, near, and intermediate after cataract surgery without spectacle correction is a boon to patients. The surgery to implant these lenses differs little from that to implant monofocal IOLs. But there are other considerations that appear to be discussed less frequently.

For instance, there are possible repercussions to the posterior segment related to the fact that these lenses are implanted. Therefore, both cataract and retinal surgeons should be aware of the potential impact these lenses could have on the posterior segment. “As these lenses gain popularity among patients with cataracts, retinal surgeons need to be aware of the challenges of working through them when performing vitrectomy,” Gaurav K. Shah, M.D., Barnes Retina Institute, St. Louis, wrote in the April 2008 issue of Retina. “However, with careful preoperative evaluation and planning, complications can be avoided.”

Problem prevention

Preventing future posterior-related problems involving presbyopia-correcting IOLs is up to the cataract surgeon. “ReSTOR [Alcon, Fort Worth, Texas] and ReZoom [Abbott Medical Optics, AMO, Santa Ana, Calif.] are acrylic lenses, and retinal surgeons have been working with this type of lens for many years,” Dr. Shah wrote. “Crystalens [Bausch & Lomb, Rochester, N.Y.] is a silicone lens, which can be a potential problem.” Specifically, this lens could be an issue in diabetic patients because of their potential need for vitrectomy, Dr. Shah noted. Silicone oil could adhere to the lens, for example. “In addition, fibrosis between Crystalens and the lens capsule can occur,” Dr. Shah wrote. “This fibrosis can be significant enough that removal of both the IOL and the capsular bag may be necessary.” Once a presbyopia-correcting lens is in place, and posterior segment surgery is needed, clearly dealing with these lenses is up to the retinal surgeon. For one, it’s important to try to maintain proper centration of these lenses, although there are challenges in doing this. “During routine posterior segment work on a pseudophakic patient, there may be small alterations in positioning of the lens,” Dr. Shah noted. “Especially if cataract surgery was performed recently, there may not be a fair amount of fibrosis within the capsular bag. In addition, because anterior vitreous is removed from behind the posterior surface of the capsular bag or the surface of the lens, the lens can move slightly.” More often, however, air-fluid exchange can move the lens. “This is of particular issue with Crystalens, where proper positioning within the bag ensures appropriate functioning of the lens,” Dr. Shah wrote. Air-fluid exchange can also cause condensation on the IOL. Those eyes that have undergone laser capsulotomy are particularly vulnerable to this. “This limitation of view can occur before the addition of laser treatment for a retinal detachment and can be problematic for the remainder of surgery,” Dr. Shah wrote. Perhaps most of all, concern among retinal surgeons with these IOLs revolves around macula work.

“When a premium IOL is in place, maintaining optimal visualization can be challenging,” Dr. Shah reported. “For example, with ReZoom, there are multiple zones that extend out from the center optic that alternate for distance and near vision. This impacts the retina surgeon because the depth perception is altered as membrane peeling is extended outward. With this change, there is the risk for iatrogenic retinal trauma from the intraocular forceps tips.” To prevent many of these IOL-related problems, Dr. Shah made some recommendations, including the following: • Note the IOL location (sulcus or in-the-bag placement).

• Minimize contact with the IOL intraoperatively to maintain centration.

• Air-fluid exchange should be avoided if possible, but often it still is needed for fixing retinal detachments. • Membrane peeling should be performed slowly and carefully during macula work.

• Patients should be informed that optical benefits of IOLs may change after retina surgery. Mark Packer, M.D., clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., also advised retina surgeons to pay attention to the type of IOL used. The Array (AMO) multifocal, for instance, has potentially made retinal surgery more difficult, he said. “The back of the eye is difficult to see through a diffractive optic,” Dr. Packer said. “It does create some optical side effects for a surgeon looking into the eye, just as it does for someone looking out of the eye, but not to a degree that would impact the performance of surgery. It’s not insurmountable, but retinal surgeons have to be aware of the potential problems.” Even with the Array lens, for example, it’s perfectly safe to perform a vitrectomy and scleral buckling surgery. “It’s all doable safely through multifocal optics,” he said.

Editors’ note: Dr. Shah has no financial interests related to this article. Dr. Packer has financial interests with Abbott Medical Optics (Santa Ana, Calif.).

Contact information

Packer: 541-687-2110, mpacker@finemd.com
Shah: gkshah1@gmail.com

Avoiding posterior segment repercussions Avoiding posterior segment repercussions
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