New Contact Lenses Can Turn Dark On Sunny Days

By David Hurst

Updated: 21:10 EDT, 19 April 2010

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It used to be that contact lenses were worn only instead of glasses. Now a new generation of lenses has transformed them into valuable health tools that can help not only with serious eye problems, but everything from migraines to diabetes.

Migranes

I see red: England cricket captain Andrew Strauss wears red-tinted contact lenses to remove harsh sun glare

I see red: England cricket captain Andrew Strauss wears red-tinted contact lenses to remove harsh sun glare

Red-tinted contact lenses have been developed to relieve the agony of migraines.

They work by filtering out wavelengths of light that over-stimulate retinal receptors - lightsensitive tissues lining the inner surface of the eye - which results in head pain.

Dr Richard Garrison, of San Jacinto Methodist Hospital in Texas, recently trialled 33 migraine patients with a history of photophobia - excessive sensitivity to light. red-tinted lenses were inserted during acute attacks, resulting in immediate pain relief for all but two of the patients.

Sportsmen and women are also starting to wear red-tinted contact lenses. England cricketers, including captain Andrew Strauss and wicketkeeper Matt Prior, recently trialled the lenses, which act like sunglasses to enable them to see the ball better in sunny conditions.

They work by filtering out bright sunlight, while relaxing the eyes to stop squinting. Unlike sunglasses, the lenses - available now - do not restrict peripheral vision. Nor do they become covered in sweat or get steamed up.

Diabetes

A new development in contact lens technology could see the end of diabetes sufferers constantly having to check their blood sugar levels using skin prick tests.

Researchers at the University of Western Ontario, Canada, have created lenses that chemically react to glucose found in tears. The lenses monitor blood glucose levels and alert wearers to any changes by changing tint, saving sufferers from having to undergo regular blood tests.

Glucose levels in tears are revealed 30 minutes behind levels in blood, but as most diabetics leave hours between their skin prick tests, the lenses will still be a more efficient and less invasive method. 

Dyslexia

Six million people in Britain have dyslexia to some degree, with one in 25 cases being severe.

Professor John Stein, of Oxford University, has estimated that one in three dyslexics could be helped by using colour filters on lenses.

Many find reading easier when text appears on coloured - rather than white - backgrounds. White light is formed of colours moving at different frequencies, some of which can cause confusion when the brain receives the information.

Breakthrough: Contact lenses are now being used to treat a number of common ailments

Breakthrough: Contact lenses are now being used to treat a number of common ailments

Tinted contact lenses filter out the problem light frequencies. The degree of tint is assessed by eye experts for each individual.

Many dyslexics are also mildly colour blind - and now there are lenses that can help, too.

These work by changing the colour of the incoming light to a shade that can be detected by the wearer.

Vision itself is not affected, but the ability to tell the difference between certain colours is improved. Colour blindness affects up to one in ten men and one in 200 women.

Corneal disease

A research team from the ­University of New South Wales in Sydney has used stem cells - ­‘master cells’ with the ability to turn into other cell types - on contact lenses to treat corneal disease.

They removed small samples of stem cells from the eyes of three ­corneal sufferers and grew them on a contact lens.

The stem cell-coated contacts were then put into their eyes for three weeks.

During that time, the stem cells moved off the lenses and began to heal the damaged corneas. Using a patient’s own cells eliminates the need for donors and means the cells will not be rejected.

A research team from the ­University of New South Wales in Sydney has used stem cells - ­‘master cells’ with the ability to turn into other cell types - on contact lenses to treat corneal disease.

Associate Professor Nick Di ­Girolamo, the university’s director of ocular research, says: ‘The procedure is ­simple and cheap. Unlike other techniques, it requires no foreign human or animal products, only the patient’s own serum, and it’s completely non-invasive. There’s no suturing or operation.

‘For the moment, we are solely treating blindness due to corneal disease from limbal stem cell failure. We hope that in the future we can make this technique widely available.

‘It is not designed to treat any ­ocular condition. But we predict that modifications to the procedure could be made so that it can be adapted to treat other blinding disorders, including those characterised by retinal degeneration.’

Damage to retinal blood vessels is behind a range of conditions that can lead to loss of sight, including many cases of age-related macular degeneration (AMD).

The disease is most common in the over-60s and around 200,000 Britons are registered as blind or partially-sighted because of it, making it the leading cause of blindness in the UK. The contact lenses used in the ­operation are widely used after surgery.

Glaucoma and cataracts

Contact lenses that release drugs such as ­vitamin E directly into the eye might soon be used to treat common eye diseases.

These include dry eye, when the eye doesn’t make enough tears, leading them to dry out; glaucoma, a chronic condition where the pressure in the eyeball increases, damaging the optical nerve and resulting in vision loss; and cataracts, a ­condition causing cloudiness in the eye lens.

Scientists at the University of Florida have developed contact lenses that can ‘dispense’ prescription drugs, over a period of weeks, to the precise spot in the eye they are needed.

The lenses are embedded with ­particles of medicine and, it is hoped, will be more efficient than eye drops, the method currently used to clear such problems.

Study author Anuj Chauhan, ­Associate Professor at the university’s department of chemical ­engineering, said: ‘Only about one to five per cent of drugs delivered via eye drops reach the cornea and the rest enters systemic circulations and can cause side-effects.

‘We’ve developed transparent ­particle-laden contact lenses that deliver drugs at therapeutic doses for five to 30 days.

‘That can lead to a 40-fold increase in the fraction of the entrapped drug that enters the cornea.’

Mr Chauhan  explained that traditional eye drops mix with tears, which then drain into the nasal cavity and penetrate the bloodstream, where the drugs can cause serious side-effects.

For instance, Timolol, used to treat glaucoma, can cause heart problems. The lenses, which are due for human trials within the next two years, have the added benefit of ­protecting the eye from sun damage because vitamin E in contact lenses blocks UV radiation.

Barbara McLaughlan, of the Royal National Institute of Blind People, said: ‘The concept of a contact lens that keeps nutrients such as vitamin E close to the eye, to treat glaucoma, seems plausible.

‘It may offer more flexibility to ­people who struggle with their ­current treatment regime.’

Health check-ups

Green light: Contacts that administer drugs direct to the part of the idea they're designed to treat have recently been introduced

Green light: Contacts that administer drugs direct to the part of the idea they're designed to treat have recently been introduced

As the eye is made up of a network of blood vessels, it offers the means to measure a range of ‘biomarkers’ — indicators found in the blood that can reveal the state of your health.

Scientists at the University of Washington in the U.S. are working on solar-powered contact lenses with in-built microscopic computers.

With a tiny radio transmitter in the circuitry, health condition reports measured from the eye’s surface could be automatically sent to ­doctors monitoring a patient.

This technology is still in early research stage.

But, potentially, it could identify illnesses that require diagnostic blood tests such as anaemia, diabetes, ­cholesterol ­levels, thyroid, kidney and liver functions, and even some sexually transmitted diseases.

Using hundreds of semi-­transparent LEDs, sensors and wireless technology, contact lenses could also display images and words. This could be used to inform the wearer when to take their tablets or seek medical help. The lenses could even be ­developed to include translating speech into ­captions in real time for the deaf.

Short-sightedness

Contact lenses worn only at night are helping people suffering from short-sightedness by gently pressing on the eye to restore it to the shape of someone with normal vision.

With short-sighted sufferers, the ­cornea is either too curved or the eyeball too long.

This means the light rays from distant objects focus in front of the ­retina, rather than directly on it, making objects seem blurred.

The new overnight lenses work by gently pressing on the cornea, reducing its curvature and so refocusing the light directly on to the retina. The lenses, available since 2008, are also made to prescription, so patients can see if they wake up at night.

Overnight lenses are made from a special hard type of plastic lens, called gas permeable, that allows oxygen to reach the eye. Tissues in the cornea maintain their transparency in part by not having blood vessels flowing through them, but this means the cornea must get its oxygen directly from the air. ­Without oxygen, the cornea will become less transparent and can scar.

Although the lenses should be worn every night for continued benefits, it takes a few days for short-sighted effects completely to wear off. An ­independent review found the new lenses could improve vision by around 70 per cent after one night, often ­correcting sight fully within a week.

Around 12 million people in the UK are short-sighted and three million already wear normal contact lenses.

Implantable Contact Lenses - another innovation already available - also offer severe short-sightedness sufferers an ­alternative to correct their vision. (The lenses can also help those not suitable for corrective laser eye surgery, because if eyes are already poor, an operation is considered too risky.)

The lenses, which cost £2,500 to £3,500 for each eye, improve vision by working with the eye’s existing natural lens, boosting its effectiveness and allowing the patient’s eye to adapt to different distances.

The 15-minute procedure causes minimum discomfort and has instant results.

Source : http://www.dailymail.co.uk/health/article-1267345/How-contact-lenses-help-save-life.html

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