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Summer babies 'are more likely to be short-sighted'
Last updated at 00:37am on 01.09.07
As many as a quarter of all cases of short-sightedness are caused by too great an exposure to sunlight in the first weeks of life
Babies born in the summer are more likely to become short-sighted in later life, a study has shown.
As many as a quarter of all cases of short-sightedness are caused by too great an exposure to sunlight in the first weeks of life, say eye experts.
They are advising all parents to put sunglasses on their babies during the first weeks.
Scientists had already established that over-exposure to sunlight caused short-sightedness in animals.
Researchers who compared the months in which babies were born with whether they needed glasses later on say the principle also applies to humans.
A study of almost 300,000 young adults - the largest of its kind - showed that those born in June and July had a 25 per cent greater chance of becoming severely short-sighted than those born in December or January.
Research leader Professor Michael Belkin, of Tel Aviv University, said it was because prolonged illumination causes the eyeball to lengthen - causing short-sightedness.
Hence the more light a newborn is exposed to, the more the eyeball lengthens and the worse the short-sightedness will be.
The mechanism which lengthens the eyeball is associated with levels of melatonin, a pigment which protects the skin against harmful rays of the sun.
In young babies not enough melatonin is released as protection, meaning they are more vulnerable to sunburn and changes to eyeball shape.
Myopia - the condition of short-sightedness which causes distant objects to appear blurred - is common worldwide.
In Britain, around 20million people - a third of the population - are myopic.
The first indication that the season of birth could have an impact on myopia came when one of Professor Belkin's students carried out a study of chickens.
It was found that the degree of short-sightedness in the chickens could be controlled by changing the amount of light they experienced in their first weeks.
Professor Belkin then studied data on almost 300,000 Israeli soldiers aged between 16 and 23.
The results, published in the journal Ophthalmology, showed that a child born in winter or autumn will have better long-range sight and less chance of requiring glasses than one born in summer.
Israel averages more than four hours of sunlight a day in the summer months, but Professor Belkin said the research was applicable worldwide - even to Britain, where summers are less sunny.
"The eye in childhood is much clearer than when we are older so it's vital that children start to wear sunglasses from birth onwards," he said.
Sight expert Professor Daniel O'Leary, of Anglia Ruskin University in Cambridge, agreed.
"At the moment we don't know the precise cause of why light exposure affects sight, but the evidence seems to prove that it is one of the reasons for people becoming shortsighted," he said.
"It would make sense to put sunglasses on babies born in the summer, or better still keep them out of strong sunlight for the first few weeks of their life."
Reader views (2)
Though it may be all very interesting, I don't think it will put anyone off, 'having-a-baby' in the summer months, not that we get much summer these days!
I for one, don't care when our baby comes, its the if and when that's important!
- Charles Linskaill, Edinburgh UK
I was born in June, am nearly 40 and have never worn glasses!
- Suzanne, Surrey
