Health News Update

Chauhan and colleagues have developed a new extended-release delivery approach incorporating vitamin E into contact lenses. The invisible clusters, or aggregates, of vitamin E molecules form what Chauhan describes as “transport barriers.” that slow down the elusion of the glaucoma medication from the lens into the eye. The drug released from the lens into the eye stays in the tears far longer than the 2-5 minutes with eye drops, leading to more effective therapy.

“These vitamin structures are like ‘nano-bricks’,” Chauhan said. “The drug molecules can’t go through the vitamin E. They must go around it. Because the nanobricks 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.”

In research with laboratory animals, 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, Chauhan said. In addition to treating glaucoma, the contacts could help other eye conditions, such as cataract and dry eye. Cataract is a clouding of the lens of the eye, and dry eye involves decreased production of tears. It affects about 2 in 10 people and can lead to more severe eye problems.

“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,” he said.

“We have developed a novel approach of extending the duration of drug release from contact lenses by including nanosized aggregates of Vitamin E in the lenses. The Vitamin E nano-aggregates force the drug molecules to travel in a tortuous path leading to increased drug release durations. Another benefit of Vitamin E incorporation is that Vitamin E is known to be an anti-oxidant, whose slow release from lenses could also help in prevention of ophthalmic diseases like cataract and glaucoma.

Furthermore, Vitamin E blocks UV radiation, leading to reduced ocular damage from the UV light. Our research has shown that Vitamin E can be loaded into the lenses without any reduction in transparency. The drug release durations from Vitamin E loaded lenses are about 100 times longer than from commercial lenses for several ophthalmic drugs including glaucoma drug timolol, anti-inflammatory drug dexamethasone, and anti-viral drug flucanozole. Thus, Vitamin E loaded lenses could be highly effective in synergistic prevention and treatment of ophthalmic diseases through extended delivery of the desired drugs and the nutraceutical Vitamin E. Animal studies in beagle dogs are ongoing to explore glaucoma treatment through Vitamin E laden contact lenses.”

“The study of rats and human patients found drops containing a nerve growth factor may stop these cells dying, and actually improve vision. It is reported in Proceedings of the National Academy of Sciences.

It is estimated that 77m people have glaucoma around the world.  The build up of intraocular pressure can sometimes be controlled through other techniques. But once pressure has started to damage optic nerve cells, called retinal ganglion cells (RGCs), it has proved impossible to recover that lost function.

And often people with glaucoma do not seek expert help until the condition is already relatively advanced. The researchers, from the University of Rome, treated rats with symptoms of glaucoma with eye drops containing nerve growth factor. The animals who were given the eye drops showed decreased levels of RGC death compared with those who did not receive the treatment.

The researchers went on to test the drops in three human patients whose intraocular pressure had started to be controlled, but who still showed signs of progressive deterioration in their vision.  In two of the patients vision improved, while in the other it was stabilised. The improvements lasted up to 18 months after the eye drops were applied.

Nerve growth factor appears to trigger chemical changes within cells that prevent them from dying in response to damage.  It might also enable cells whose function had begun to be damaged to bounce back. And it might boost the capacity of healthy RGCs to form new connections within the optic nerve, to compensate for any damage that had already taken place.

However, nerve growth factor cannot rescue RGCs that have already died – in common with brain tissue, the optic nerve cannot regenerate. Lead researcher Dr Stefano Bonini said: “Although neuroprotection in glaucoma has already been attempted with several compounds, this is the first time that an improvement in visual function is observed in patients with advanced optic nerve damage.”

David Wright, chief executive of the International Glaucoma Association, warned against drawing firm conclusions from such a small study – but said the results were encouraging.  He said: “There have been many false dawns in the search for neuro-protective agents for the treatment of glaucoma and it is a feature of research on other compounds that early promise does not always translate into clinical effectiveness when larger studies are undertaken.”