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CRSToday Europe News — July/August 2008
Animal Work Showed Good Biocompatibility of Artificial Cornea
A polymer gel formulation is showing promise as a material for use as an artificial cornea, according to researchers at Stanford University, including Christopher Ta, MD, lead researcher and Associate Professor of Ophthalmology at Stanford.
Funded by the National Institutes of Health and developed by Curtis W. Frank, PhD, Stanford University Professor of Chemical Engineering, the artificial cornea consists of interwoven polymer gels that are similar to those used in soft contact lenses. The project began approximately 5 years ago at Stanford. To date, researchers have conducted rabbit studies to examine the technology's biocompatibility, cellular adhesion, and toxicity. In the Journal of Biomedical Materials Research,1 researchers indicated that when implanted into rabbit eyes, the material supported epithelial cell migration; however, "the rate of migration and morphology of the epithelium were not normal." Results will be used to further optimize the bioactive hydrogels for use as an artificial cornea and possibly corneal onlays.
"We found that the material is biocompatible, and the cornea maintained its clarity. We ound that diffusion of nutrients through the polymer was adequate to support epithelial cells," Dr. Ta said in a telephone interview with CRST Europe.
Findings indicate that the artificial cornea project may be heading in the right direction; however many challenges must first be overcome before the artificial cornea can be a viable treatment for humans, Dr. Ta said.
Researchers are focusing their efforts on (1) creating pores in the corneal material to facilitate cellular integration, (2) strengthening the material for suturing, and (3) modifying the surface of the polymer with biological components that would facilitate cellular adhesion. Researchers have also focused on screening and developing materials that may be suitable for an artificial cornea.
"We were looking for an optically clear, biocompatible, mechanically strong material that allows for integration of the tissue and diffusion of nutrients through the material to support epithelial cells," Dr. Ta said.
Two other models of an artificial cornea are currently available; however, Dr. Ta stresses that all pioneering technologies have limitations. "There are always improvements that can be made in the design and material. That is what we are trying to accomplish with our work. If we could alleviate the problem of the limited supply of human donors or complications with preserving the tissue, there are many people worldwide who could benefit [from the creation of an artificial cornea to use in transplantation cases]," Dr. Ta concluded.
Christopher N. Ta, MD, is an Associate Professor of Ophthalmology, Stanford University, and the lead researcher on this artificial cornea project. Dr. Ta may be reached at e-mail: cta@stanford.edu.
Novartis Makes First Step Purchase of Minority Interest in Alcon
Novartis International AG (Basel, Switzerland) and Nestlé (Vevey, Switzerland) completed the first step in the purchase and sale of 74 million shares of common stock of Alcon, Inc. (Huenenberg, Switzerland), which is currently owned by Nestlé. This transaction followed an agreement made April 6 that granted Novartis approximately a 25% minority stake in Alcon. Nestlé will retain approximately 52% of Alcon's outstanding shares and remain the company's majority shareholder.
According to the agreement, Novartis possesses a call option to purchase Nestlé's remaining Alcon common shares. The agreement provides Nestlé with a put option to sell its remaining Alcon shares to Novartis. These options may be exercised between January 1, 2010 and July 31, 2011. If either company exercises its respective option, Novartis would become the majority shareholder of Alcon with approximately 77% of its issued shares.
Additionally, Alcon's board of directors was expanded from eight to 10. James Singh, Nestlé's Executive Vice President and Chief Financial Officer, and Daniel Vasella, MD, Novartis' Chairman and Chief Executive Officer, were appointed as the two new directors.
Crystalens HD Received FDA Approval
The US Food and Drug Administration (FDA) approved the Crystalens HD (Bausch & Lomb, Rochester, New York) for presbyopia correction. The HD is the fourth-generation Crystalens IOL, which is currently the only FDA-approved accommodating lens.
The Crystalens HD is designed to improve patients' functional near vision. The company reportedly shaped the surface of the HD with a proprietary optical modification, thus improving the IOL's near performance and preserving its intermediate and distance performance.
According to a Bausch & Lomb news release, 80% of 125 eyes implanted with the Crystalens HD were functioning at J2 or better at 4 months postoperative. All study participants had visually significant cataracts, less than 1.00 D of corneal astigmatism, and the potential for achieving a BCVA of 20/25 or better in both eyes.
The FDA first approved the Crystalens for presbyopia correction in November 2003.
Strong Evidence for a Genetic Marker for Myopia
Gu Zhu, MD, and colleagues confirmed previous research that myopia and hyperopia have a genetic component.1 Reporting their results in Ophthalmology, Dr. Zhu et al found that genetic factors explained approximately 80% of the values for axial length in the eyes of fraternal and identical twins. The investigators also identified the probable location of the genes that determine axial length.
Dr. Zhu's team analyzed the proportional impact of genetic and environmental factors on axial length measurements taken from 893 patients enrolled in the Tasmania Twin Eye and Brisbane Adolescent Twin studies in Australia. After performing a genome scan on a subset of 318 individuals, the researchers said they found strong evidence for the role of chromosome 5 in the inheritance of axial length.
The investigators have launched a genomic analysis of a larger study group to confirm and refine their findings, according to the study. "Identifying strong genetic markers could further this and other preventive efforts," the study's authors wrote.
Strengthening LASIK Flap Proposed to Prevent Ectasia
Finding a method to strengthen the LASIK flap may avoid post-LASIK ectasia, according to Herbert E. Kaufmann, MD, of New Orleans.
During his presentation at the World Ophthalmology Congress in Hong Kong, Dr. Kaufmann proposed that adding irritation, such as TGF-beta growth factor or talc, may trigger wound healing, thereby avoiding an ectatic outcome.
"Maybe it's possible to get the flap to contribute to tectonic strength if we could stimulate healing of the flap and get a strength in the peripheral vertical wound, like we get in lamellar keratoplasty," Dr. Kaufmann said.
Dr. Kaufmann summarized results of a recent rabbit study, which calculated the effects of raised intraocular pressure (IOP) in eyes with sutured versus nonsutured flaps. Dr. Kaufmann and colleagues observed that the sutured flaps did not bulge; however, eyes with nonsutured flaps bulged and had steep topographies. Dr. Kaufmann concluded that the sutures caused fibrotic scars, which avoided bulging and promoted healing.
Because adding sutures to all LASIK flaps is not a practical solution, Dr. Kaufmann said that the same positive effect may be produced by adding irritation to the area.
IOLs: Predictions for the Future
Although accommodating IOLs had only 1% of the market share in 2007, their use may start to rise, according to Richard L. Lindstrom, MD, of Minnesota.
Monofocal IOLs dominated the market with 95%, and multifocal IOLs followed with 4% of market share, Dr. Lindstrom said.
"I think there is quite a different future for monofocal, multifocal, and accommodating [IOLs]," said Dr. Lindstrom, during a presentation at the World Ophthalmology Congress in Hong Kong. He forecast the future IOL growth pattern as one that will ultimately be dominated by accommodating IOLs; multifocal IOLs will experience a surge before declining, and monofocal IOL use will slowly and steadily decline, too, he said.
Results of a recent survey of ophthalmologists indicated that the accommodating IOL is the preferred presbyopia-correcting IOL; Dr. Lindstrom said that when asked what IOL the surgeon would choose for his own eye, the majority chose an accommodating IOL.
Additionally, toricity will be a consideration for future IOL models, said Dr. Lindstrom.
IntraLase Bioptics Addresses High Astigmatism
Bioptics procedures (ie, combining LASIK with phakic or multifocal IOLs) can provide spectacle independence to patients with high astigmatism, according to a presentation in Hong Kong.
Michael Knorz, MD, said that implanting a carefully selected IOL before or after creating a flap with the IntraLase femtosecond laser (Advanced Medical Optics, Inc., Santa Ana, California) can be combined with wavefront-guided LASIK to achieve spectacle independence for these patients. IntraLase flap creation prior to IOL surgery allows for earlier laser vision correction, he said during a presentation at the World Ophthalmology Congress.
Dr. Knorz conducted a study of IntraLase bioptics in 29 eyes (19 patients) implanted with multifocal IOLs; 20 eyes were implanted with the Tecnis Multifocal (Advanced Medical Optics, Inc.). Results revealed that 40% of eyes needed additional correction to see well at near distances; however, the IOL did not induce significant higher-order aberrations, Dr. Knorz reported.
Dr. Knorz said that he combines phakic IOLs or diffractive multifocal IOLs with IntraLase flap creation and CustomVue wavefront-driven ablations to achieve "perfect vision." He uses standard ablation in combination with refractive multifocal IOLs.
Industry Appointments
Nidek Co., Ltd. (Gamagori, Japan), announced two appointments to its management. Hideo Ozawa, founder of Nidek, was appointed Chairman of the Board, and Motoki Ozawa, Nidek's Vice President since 2005, was promoted to President and Chief Executive Officer.
John W. Sheets Jr., PhD, was named Corporate Vice President and Chief Technology Officer of Bausch & Lomb. He will lead the company's global research and development efforts. Dr. Sheets has more than 25 years of experience in the medical device industry.
In a separate news release, Bausch & Lomb named Joseph Barr, OD, MS, the Vice President of Global Clinical & Medical Affairs and Professional Services, Vision Care. Dr. Barr will head up a team of clinical researchers, medical affairs personnel, and professional services professionals.
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