Vitamin E contact lenses "may treat glaucoma"

Specially designed contact lenses loaded with vitamin E and drugs to treat glaucoma can keep the medicine near the eye up to 100 times longer that lens with drugs only, new research has found.

Glaucoma is second only to cataracts as the leading cause of vision loss and blindness in the world. It affects almost 67 million people, and eye drops designed to reduce the build-up of pressure in the eye resulting from the disease are one of the most common forms of treatment.

The problem with eye drops is that within minutes tears carry the drug away, which means it does not reach the tissue it is targeting.

The alternative approach being investigated is to create contact lens filled with a glaucoma treatment drug, which would make it more effective by ensuring the medicine remains in contact with the eye.

In the new approach, a team of scientists at the University of Florida added vitamin E to the lens alongside the drugs. The molecules of vitamin E act as a form of barrier to the medicine, slowing down its release into the eye. The drug released from the lens into the eye stays in the tears far longer than the 2 to 5 minutes with eye drops, leading to more effective therapy.

"These vitamin structures are like 'nano-bricks'," said Anuj Chauhan, who lead the team. "The drug molecules can't go through the vitamin E. They must go around it. Because the nano-bricks are so much bigger than the drug molecules – we believe about a few hundred times bigger – the molecules get diverted and must travel a longer path. This increases the duration of the drug release from the lenses."

So far the lenses have only been tested on animals, but tests show that the lenses containing vitamin E nanobricks administered drugs up to 100 times longer than most commercial lenses. The lenses could be designed for continuous wear for up to a month, Dr Chauhan said.

It is hoped that the technique could also be used with other conditions such as cataract and dry eye.

"Vitamin E is a proven nutraceutical that in small amounts is good for the eye because of its ant-oxidant properties. Also Vitamin E presence in the contact lenses blocks UV radiation, leading to increased protection against the UV light. Our research has shown that the vitamin can be loaded into the lenses without any reduction in transparency. We believe it could be helpful in disease treatment and in prevention as well," Dr Chauhan added.

The research was presented at the 239th National Meeting of the American Chemical Society (ACS).

This article was published on Thu 25 March 2010