EyeNet Magazine



   
 
Clinical Update: Cataract
Opacification of IOLs: A Problem Often Misdiagnosed?
By Laura J. Rongé, Contributing Writer
 
 

After what seemed like a wild goose chase, a frustrated 60-year-old woman came to Gerald W. Zaidman, MD, FACS, and told him this story:

About two years after having cataract surgery on both eyes, this patient started losing vision in her right eye. She went to a local ophthalmologist, who sent her to a second ophthalmologist, who thought she had posterior capsular opacification. He did a laser capsulotomy, but she didn’t get better. He sent her to a retinal specialist, who recommended a vitrectomy. She got nervous and decided not to have a vitrectomy. She returned to the first ophthalmologist who redid the capsulotomy because he thought it wasn’t big enough. She didn’t get better. That ophthalmologist sent her to a neurologist, who ordered MRI and CT scans, but her problem remained a mystery. Finally, she came
to Dr. Zaidman’s department.

“When I sat down with her at the slit lamp, I saw that her IOL was opaque. That is why she could not see,” said Dr. Zaidman, professor of ophthalmology, New York Medical College, and associate director of ophthalmology, Westchester Medical Center.

Dr. Zaidman posted an e-mail about the case and began to hear from other surgeons. He collected 14 stories of delayed opacification of a hydrophilic acrylic IOL and found that many of these patients had either had or been recommended to have unnecessary procedures, including pars plana vitrectomy, YAG laser capsulotomies and neurologic workups. “One of the patients, after having a vitrectomy and an IOL exchange, developed endophthalmitis and lost the eye,” he reported. “All they needed was identification of the fact that the IOL was opaque. If their vision was bothersome, we would offer them an IOL exchange.”

If the posterior capsule looks clear, but the fundus looks shadowy or hazy, suspect an opaque IOL, Dr. Zaidman said. “If you are not sure, send the patient to somebody who can recognize an opacified IOL. Don’t jump to the conclusion that the person needs a YAG laser capsulotomy or a vitrectomy.”

Hydrophilic Acrylic Lenses
Liliana Werner, MD, PhD, assistant professor of ophthalmology, University of Utah, Salt Lake City, has studied opacified lenses in the laboratory. “In the past six years, we have received many hydrophilic acrylic lenses that were explanted because of lens opacification,” she said. “This opacification results from calcium phosphate deposits on the surfaces or the internal substance of the lens.”

A Problem on the Surface
Dr. Werner explained that surface deposits were seen with two major lenses.

Hydroview. The Hydroview IOL, developed by Bausch & Lomb Surgical, was introduced outside the United States in 1995, and opacification was not seen with the early model of this lens. In 1997, Bausch & Lomb changed the lens packaging to add the SureFold holder/folder and a silicone-sealing gasket (Hydroview 1.0 IOL). The Hydroview was approved for use by the FDA in 1999, and in May of that year the manufacturer first received reports about “clouding” of a small number of lenses.

In the 40 explanted Hydroview 1.0 lenses that Dr. Werner and her colleagues analyzed, the opacification appeared anywhere from five to 48 months after cataract surgery.¹

Bausch’s investigation found that silicone had migrated from the packaging gasket to the lens, triggering a calcification process in some patients. The packaging was redesigned, and by May 2003 more than 323,000 new lenses were distributed worldwide (Hydroview 1.5). Dr. Werner said that, to the best of her knowledge, calcification has not been reported in this new model.

Memory Lens. This lens, developed by Ciba Vision, was introduced on the international market in 1994. In 1999, episodes of sterile hypopyon led the manufacturer to recall some lots of the Memory Lens (models U940A and U940S) in 2000.²

By March 2004, Dr. Werner and colleagues had analyzed 106 Memory Lens IOLs explanted because of opacification that occurred anytime from three to 81 months after cataract surgery. Ciba Vision investigated the problem, changed the lens polishing process and reintroduced the Memory Lens in October 2000 (models U940S and CV232, the latter with a square-edge design).

Dr. Werner has heard no reports of opacification since the reintroduction. Ciba has since sold the Memory Lens to another company, IOL Tech.

A Problem Inside
In two other hydrophilic acrylic lens designs, Dr. Werner and her colleagues found calcium phosphate deposits inside the lens material.

SC60B-OUV IOLs. These lenses were produced by Medical Developmental Research (now EyeKon Medical). Since 1999, Dr. Werner’s team analyzed 59 of these explanted lenses and found that impaired vision occurred about one year after cataract surgery.

Aqua-Sense. These lenses are marketed by Ophthalmic Innovations International Inc. Since early 2001, Dr. Werner and her colleagues  have analyzed 21 of these lenses, and determined that symptoms appeared during the first year after surgery.

Dr. Werner explained that both Medical Developmental Research and Ophthalmic Innovations International changed their lens designs, manufacturing processes and packaging after these problems were discovered.

Silicone Lenses
Calcification of silicone lenses has been seen only in patients with a vitreous condition called asteroid hyalosis. Dr. Werner pointed out that this is a rare phenomenon, with only five cases published in the literature.

“We recently analyzed three silicone-plate IOLs (model AA4203, Staar Surgical) explanted because of calcified deposits on their posterior surfaces about two years after surgery. These patients all had asteroid hyalosis in the corresponding eye,” she said. Nick Mamalis, MD, professor of ophthalmology and visual sciences, University of Utah, Salt Lake City, explained that in asteroid hyalosis, calcium deposits are already present in the vitreous.

In each of these cases, the patient had had a laser capsulotomy, and Dr. Werner noted that the direct contact between the posterior IOL surface and the vitreous accelerated the opacification. “It is possible that this may occur in all eyes with this vitreous condition, regardless of the IOL design or material implanted, but only in a few cases is it significant enough to require explantation,” Dr. Werner said.

What to Do
To avoid misdiagnoses and unnecessary procedures, always consider IOL opacification when a patient presents with visual loss after cataract surgery, the experts advised. These patients don’t always have terrible vision. Dr. Zaidman noted that vision in his case series ranged from 20/25 to 20/200. “Regardless of their visual acuity, however, they all complain that it is a gray-brown, foggy vision. They have no contrast,” he said.

Try to find out if they have a hydrophilic acrylic lens, he suggested. The patient may have saved the IOL card from their cataract surgery. Do a careful high-power, slit-lamp examination. “This will help doctors to differentiate between deposits present on the external surfaces of the lens, opacities within the lens or opacities at the level of the posterior capsule or the vitreous,” said Dr. Werner.

“In our lab, we found that the deposits on the surfaces of the Hydroview lenses were larger in size and confluent in some areas, giving a more crustlike appearance,” she explained. “The Memory Lens IOLs generally exhibited a fine granularity covering the external optic surfaces,” she said. In the SC60B-OUV and Aqua-Sense lenses, she noted that the opacification produced a clouding effect, like a nuclear cataract.

“When you look carefully at these with a slit lamp, you can see the calcium deposits on the lens itself. It might be subtle, but you should be able to differentiate where this opacification is occurring,” said Dr. Mamalis. 

More Than Meets the Eye
In the United States today, cataract surgeons most often use hydrophobic acrylic or silicone lenses, Dr. Mamalis said. He pointed out that opacification occurs mainly in hydrophilic acrylic, or hydrogel, lenses, which have not obtained widespread popularity in this country.

Researchers have identified some causative factors for each lens design, but Dr. Werner noted that the problem with hydrophilic acrylic lenses appears to be multifactorial and may involve patient-related factors, such as metabolic imbalances.

In the meantime, ophthalmologists must maintain vigilance so that patients receive proper diagnosis and treatment. “These lenses are still out there, and ophthalmologists should be aware that they can opacify,” Dr. Mamalis said. “When we hear about something like this in our lab, it is often the tip of the iceberg.”

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1 Neuhann, I. M. et al. Ophthalmology 2004; 111:2094–2101.
2 Tehrani, M. et al. J Cataract Refract Surg 2004;30:115–122.

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Dr. Mamalis conducts contract studies for multiple IOL manufacturers, but has no direct financial interests in these products. Drs. Werner and Zaidman have no financial interests. Analyses of explanted IOLs at the John A. Moran Eye Center have been supported in part by the Research to Prevent Blindness Olga Keith Wiess Scholar Award.


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