'Smart' glasses that could slow down sight loss
The prevalence of short-sightedness is increasing, but a new type of lens that better focuses light could make an important difference
SCIENTISTS have developed glasses with 'rings' in the lenses to halt or slow the progress of myopia, or short-sightedness, where distant objects appear blurred.
The concentric rings are designed to focus light onto the retina, making images clearer, and by doing so, slow the rate at which the eyeball changes shape - a hallmark feature of myopia.
In a Chinese study, 167 children who wore the glasses for 12 hours daily saw an up to 70 per cent slowing in the progression of their myopia after two years.
Myopia is becoming more common. In the UK it affects almost 40 per cent of the population, compared to about 27 per cent in the 1970s.
It occurs when the eyeball grows too long, and becomes oval-shaped rather than round. This alters the way light hits the retina, the light-sensitive cells at the back of the eye which send the visual images we see, to the brain.
The lengthened eyeball makes light focus in front of the retina, meaning near objects are clear and focused, yet those more distant appear blurry.
Exactly why myopia occurs is unclear. Genes play a part, but environmental factors are implicated too, given the big rise in cases in recent years.
Little time spent outdoors is thought to figure. One theory is that bright light triggers the release of dopamine (a chemical messenger) from the retina, which may stop the eye lengthening.
The problem may be worsened by focusing on phone screens or reading for long periods.
Glasses help, yet stopping or slowing myopia progression has been the Holy Grail of eye research. Special contact lenses can be effective, but these aren't suitable for all, particularly children.
The Stellest spectacles look like regular glasses but use HALT (highly aspherical lenslet target) technology, consisting of 11 rings of 1mm inside the lenses.
According to the maker, "the power on each ring has been ingeniously determined to guarantee a volume of signal always in front of the retina and following its shape, to achieve consistent myopia slowdown".
In myopia, when the outer areas of the retina detect the out-of-focus light from distant objects, the eyeball responds by growing longer to sharpen the images.
But the more it grows to try and bring these images into focus, the greater and faster the progression of myopia.
The Stellest lenses stop this by changing the nature of light that reaches the periphery of the retina. The rings are oval-shaped to mirror the shape of the eyeball - this is thought to better focus the light rays on the retina.
In a study by Wenzhou Medical University, China, 167 children wore the glasses for at least 12 hours a day and found they slowed progression of myopia by an average 67 per cent after two years.
After the first year, the eye growth in 90 per cent of children wearing the specs was similar to or slower than children without myopia. Two-thirds did not need a prescription change, it was reported at the recent Association for Research in Vision and Ophthalmology conference.
Manufacturer, Essilor, plans to roll out Stellest specs in other Chinese hospitals, followed by launches in other countries.
Professor Bruce Evans, director of research at the Institute of Optometry, says: "The new designs of lenses for myopia control, of which Stellest is one, are game-changers. They make myopia control much easier, both for practitioners and for patients.
"On average, children who wear the lenses will be less short-sighted, and in later life will have a lower risk of the eye diseases that can accompany myopia."
© Daily Mail