Calcium deposits on Hydroview IOLs may come from silicone packing

Several factors, including silicone gaskets in the packaging, may be acting as catalysts for accumulation of calcium ions on IOLs.

CHARLESTON, S.C. — The accumulation of calcium deposits on some Hydroview IOLs (Bausch & Lomb, Claremont, Calif.) may be due to several causes and will require careful follow-up to determine how significant the phenomenon is, according to Liliana Werner, MD, PhD.

In a study performed at the Center for Research on Ocular Therapeutics and Biodevices, under the direction of David Apple, MD, Dr. Werner and Suresh K. Pandey, MD, found that the optical surfaces of a series of Hydroview IOLs explanted approximately 1 year postoperatively were covered with a layer of deposits composed of multiple fine, translucent spherical-ovoid granules.

According to Bausch & Lomb, 31 of approximately 3,500 sites where Hydroview IOLs have been implanted have reported this clouding of the lenses. There have been 309 reports of presumed calcification, with 96 of this number clinically significant enough to warrant replacement. Bausch & Lomb estimates that in 2000, 2.4 lenses in 10,000 IOLs will have needed to be explanted, an incidence of 0.024%.

Clinical findings

According to Dr. Werner, the Hydroview IOL has been implanted in more than 400,000 eyes worldwide. For the few patients who developed calcium on the IOL, it was usually detected 1 year after implantation.

“The patient is really very happy immediately after the surgery,” Dr. Werner said. “There is absolutely no problem, good visual acuity, no important inflammatory reaction. It’s really a very quiet eye.”

At the 1 year follow-up visit, the surgeons could see a haze on the surface of the IOL in some patients.

“In general, the affected patients presented with a decreased visual acuity 1 year after the cataract surgical procedure. The slit-lamp examination revealed a dusty haze or brown granularity covering the optical surfaces of the lenses,” Dr. Werner said. “The surgeons performed YAG laser trying to clean the surfaces of the lenses, but this was unsuccessful.”

In a Feb. 2001 letter to surgeons who have implanted the Hydroview IOL, Bausch & Lomb described the investigation into the phenomenon. Surface chemistry studies identified the lens deposits as a layered mixture of octacalcium phosphate, fatty acids, salts, and small amounts of silicone. An in vitro model was then constructed to find out how the material got onto the lens. This model, according to Bausch & Lomb, revealed a migration of silicone from a gasket in the lens packaging onto the surface of the IOL. The model also showed that in addition to silicone, fatty acids had to be present to attract calcium ions to the lens surface.

A separate retrospective clinical case/control study was conducted by Bausch & Lomb at the sites where the highest incidences of Hydroview calcification were reported. A compromised blood-retinal barrier seemed to be associated with the appearance of calcified deposits, according to the company.

“Part of the package component contains silicone, and the manufacturer believes some of the silicone material comes off the packaging onto the lens optic. It then appears to be a catalyst to help the formation of calcium,” Dr. Apple said.

“Bausch & Lomb believes that the fatty acids and silicone, perhaps in association with a metabolic disease in the affected patient, could result in the calcification,” Dr. Werner said.

History

The group here received Hydroview IOLs for investigation from several sites around the world.

“The first case we had was explanted by Dr. Crayford from Australia,” Dr. Werner said. “From May 1988 to September 1988, this same surgeon performed 145 implantations of these lenses and as of May 2000, he performed three explantations and he observed a total of six cases.”

One of these patients was diabetic and one had hypertension.

“The other cases we received were sent by Dr. Ohrstrom from Sweden,” Dr. Werner said. “In the past 3 years, Dr. Ohrstrom implanted 3,500 lenses of this design. He observed, as of May 2000, 12 similar cases and he performed four explantations. Other explants were sent by Dr. Gravel from Canada and by Dr. Apel from Australia.”

Dr. Werner and Dr. Apple tried to find similarities between the cases that had calcification.

“We were thinking that some viscoelastic solutions might be involved in the process, but it isn’t always the same viscoelastic solution in each case,” she said. “It doesn’t seem to be related to the solutions used during the surgery as the phenomenon is late postoperative. It’s not immediately after the surgery. But maybe it’s something related to metabolic imbalance, because the majority of the patients are diabetics. This would be one of the factors, but there would be other factors involved.”

U.S. launch

The Hydroview IOL has been available internationally for several years. Although the lens was approved by the Food and Drug Administration for U.S. marketing in November 1999, Bausch & Lomb postponed its U.S. launch. The company intends to make the Hydroview available to U.S. surgeons in a new package.

Drs. Werner, Apple and Pandey told Ocular Surgery News that they suggest future patients receiving the Hydroview in the new packaging be carefully followed for 1 to 2 years after surgery to verify that the problem does not recur.

Slit-lamp photograph of Hydroview IOL showing opacification. The imprints of the insertion forceps can be observed.	IOL calcification as it appears under light microscopy.
Gross photograph of an explanted opacified Hydroview lens.	Positive staining of the deposits on the surface of the lens with 1% alizarin red.

For Your Information:

• Liliana Werner, MD, PhD, is visiting assistant professor at the Storm Eye Institute, Medical University of South Carolina, 167 Ashley Ave., P.O. Box 250676, Charleston, SC 29425; (843) 792-0777; fax: (843) 792-7920. Dr. Werner has no direct financial interest in any product mentioned in this article, nor is she a paid consultant for any company mentioned.
• David Apple, MD, is head of the Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, 167 Ashley Ave., P.O. Box 250676, Charleston, SC 29425; (843) 792-2760. Dr. Apple has no direct financial interest in any product mentioned in this article, nor is he a paid consultant for any company mentioned.