EU project develops new plastics for lenses in cataract surgery

Brussels, Sep 2005

Cataracts are the leading cause of visual impairment among ageing adults. When clouded vision blights everyday life, an operation to remove the cataract is the only solution. The EU project MIRO is developing new plastics for thinner intraocular lenses to improve operating techniques. The new lenses will be available for patients by 2006.

Cataracts do not form on the eye, but rather within the eye. A cataract is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images. The lens is contained in a sealed bag or capsule. As old cells die they become trapped within the capsule. Over time, the cells accumulate, causing the lens to cloud, and making images look blurred or fuzzy.

For most people, cataracts are a natural result of ageing. The first signs usually appear after the age of 50, and include clouded vision or increased sensitivity to glare, particularly when driving at night. Cataracts are the leading cause of sight loss among adults aged 55 and older. Eye injuries, certain medications, and diseases such as diabetes and alcoholism have also been known to cause cataracts.

Recent studies also show that permanent damage to the eyes can occur when they are not adequately protected from prolonged sun exposure. Frequent exposure over a long period of time can lead to damage of the internal structures of the eye, including the lens and the retina. According to experts, thanks to depletion of the ozone layer, the amount of UV light we are exposed to is getting higher and higher each year, and children exposed to high UV light levels today could be at risk of developing cataracts sooner.

Once a cataract has formed on the lens, no treatment will improve vision or reduce the cataract but surgical removal of it. After 1948 a new method to compensate the loss of refractive power of the eye after cataract extraction became available: intraocular lenses (IOLs) placed surgically into the eye and made of a rigid optical part and a flexible haptic part, with plastic side struts to hold the lens in place within the capsular bag of the eye. Prior to the development of IOLs, cataract patients were forced to wear thick glasses or contact lenses after surgery, and were essentially blind without their glasses, since the natural lens that had been removed wasn't replaced with anything.

With IOLs, the surgery is done using very small incisions, breaking up the cataract and removing it, and then inserting a new plastic lens into the eye. Driven by an increasing number of small enterprises (SMEs) this market gradually developed over the following 40 years.

Around 1990 a new micro-invasive surgical technology for cataract extraction became available, requiring only a 3 mm incision: phacoemulsification or phaco. The surgeon destroys the old, clouded lens with an ultrasound instrument and vacuums it out before implanting a new plastic lens, or implant, in the eye. This caused the development of IOLs, whose 6 mm diameter optics can be folded and inserted through a 3 mm opening of the eye. This operations are usually extremely successful, and as only extremely small cuts are made to the eye, no stitches are normally needed, and the eye heals extremely rapidly after the operation. In the years following, the IOL market in the US, Western Europe and Japan reached maturity: the annual increase in operations became smaller, prices for IOLs decayed and US based multi-national companies emerged by purchasing more and more SMEs. Over two million such lenses are implanted every year in the European Union.

Currently we are at the threshold of a new surgical technology, allowing cataract removal through incisions smaller than 1.5 mm. This will drive a demand for a new generation of rollable IOLs with extremely thin optics, requiring elastic materials with refractive index far beyond what has been achieved so far. Operating techniques using such small incisions do exist already, but no suitable intraocular lenses are yet available on the market.

MIRO, a collaborative research project, gathers nine research centres and companies from five EU countries with the aim of developing new plastics for this purpose and the technology to manufacture IOLs out of them, as well as the required surgical instruments for their implantation into the eye. MIRO, which stands for micro incision research in ophthalmology, is supported with 1.18 million euro under the horizontal research activity under the Sixth Framework Programme (FP6) for projects involving SMEs.

'Surgeons are aiming to reduce the width of the incision for the operation from three millimetres to only one and a half,' explains Joachim Storsberg, a chemical engineer at the German research organisation Fraunhofer Institute for Applied Polymer Research, IAP, and participant in the MIRO project. 'Folding intraocular lenses made of high-performance polymers permits a type of micro-invasive surgery that can be performed on outpatients and is even more readily tolerated than the operating methods used until now.'

CORONIS GmbH, prime contractor of the project, has invented a method to create such ultra-high refractive index composite materials. As for the lenses, the refractive index of intraocular lenses currently available is about 1.5mm, and the greater the refraction index, the thinner the lenses can be made. The Fraunhofer Institute has already attained a value that is significantly greater than for any lenses available so far. The most promising materials are two highly refractive materials with high optical transparency and flexibility - in other words, they can be folded and rolled up. Both are non-toxic, biocompatible and durable in shape. When frozen they can be machine-worked or produced directly in the desired form by means of photochemical polymerisation.

'We hope that the new lenses will be available for surgery on patients by 2006,' says Dr Wolfgang Müller-Lierheim, project coordinator for the German company CORONIS GmbH. The clinical trials are also expected to be completed by next year.
For further information, please contact:
Dr Wolfgang Müller-Lierheim
E-mail: ml_wgk@online.de
or Dr. Joachim Storsberg
Tel: +49 331 568-1321
E-mail: joachim.storsberg@iap.fraunhofer.de

CORDIS RTD-NEWS / © European Communities
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