Friday, November 22, 2013
Women who take the Pill for more than three years have double the risk of eye condition that leads to blindness
The effect described below is larger than the usual rubbish but the finding is still only a correlational one with no obvious causal path. If estrogen is at fault, women should be going blind all over the place
Women who take the contraceptive pill for more than three years are twice as likely to suffer from an eye condition that can lead to blindness, a new study has found. The research revealed women who take the pill are more likely to develop glaucoma.
The condition occurs when the drainage tubes within the eyes become blocked, preventing fluid from draining properly and causing pressure to build up, damaging the optic nerve and nerves from the retina.
In England alone around 480,000 people have the most common form of glaucoma, which is most often seen in white Europeans.
The new study is the first to establish an increased risk of glaucoma in women who have used oral contraceptives.
Scientists have now urged gynaecologists and ophthalmologists to tell women of the increased risk and to screen for the condition.
The eye damage caused by glaucoma cannot be reversed but prompt treatment will halt the progression of the condition.
Dr Shan Lin of the University of California in San Francisco said: ‘This study should be an impetus for future research to prove the cause and effect of oral contraceptives and glaucoma.
‘At this point, women who have taken oral contraceptives for three or more years should be screened for glaucoma and followed closely by an ophthalmologist.’
The researchers used data from 2005 to 2008 in the National Health and Nutrition Examination Survey.
This included 3,406 female participants aged 40 years or older from across the U.S. who completed the survey’s vision and reproductive health questionnaire and underwent eye examinations.
It found women who had used oral contraceptives, no matter which kind, for longer than three years were 2.05 times more likely to also report that they had been diagnosed with glaucoma.
Although there was no direct causative effect of oral contraceptives on the development of glaucoma, it indicates that long-term use of oral contraceptives might be a potential risk factor for glaucoma.
Previous studies have shown that oestrogen may play a significant role in the development of glaucoma.
The finding was presented at the 117th Annual Meeting of the American Academy of Ophthalmology in New Orleans.
About one in 50 white Europeans over the age of 40 have glaucoma, as do one in 10 people over the age of 75.
The most common form of glaucoma - chronic open-angle glaucoma - progresses very slowly and often does not cause any noticeable symptoms.
However, over time the patient will start to lose vision from the outer rim of their eye.
The loss of vision will slowly move inwards towards the centre of the eye.
Can’t get children to eat greens? Blame it on the survival instinct
It is a question that has perplexed parents for decades: why do children refuse to eat greens? Now, two American academics believe they have the answer.
After studying dozens of toddlers as they played with various objects, the researchers noted that they were far more reluctant to grasp plants than artificial items such as spoons or pipe cleaners.
They believe this is because evolution has biologically programmed children to be wary of flora as it may contain potentially hazardous toxins.
Due to a susceptibility to illness or injury in the early years of life, the body has designed an inbuilt defence mechanism that limits a child’s contact with plants, they think.
The researchers believe this is why infants in the study were wary of grabbing plants — and why children turn their noses up when faced with a plate of broad beans.
The findings are published in an academic paper by Dr Annie E Wertz and Dr Karen Wynn, both psychologists at Yale University, titled “Thyme to touch: Infants possess strategies that protect them from dangers posed by plants”.
They wrote: “Throughout human evolution … plants have been essential to human existence. Yet, for all of these benefits, plants have always posed very real dangers.
“Plants produce toxins as defences against predators that can be harmful, or even deadly, if ingested. Some plants also employ physical defences, such as fine hairs, thorns, and noxious oils that can damage tissues and cause systemic effects.”
They added: “We predicted that infants may possess behavioural strategies that reduce their exposure to hazards posed by plant defences by minimising their physical contact with plants.”
To test their theory, the academics studied how children aged eight to 18-months-old reacted when presented with a variety of objects while sitting on their parent’s lap.
In each case they would place six objects, one at a time, in front of the infant while saying “look what I’ve got” and timing how long it took before they clasped the item. Parents were told to keep their eyes shut to minimise their influence. By repeating the same test on almost 100 subjects, the researchers discovered significant variations in the time it took for children to reach out for different items.
On average, it took 3.4 seconds for a child to reach out for shells, 4.6 seconds for lamps and spoons but almost 10 seconds for parsley and basil plants, twice as long as many non-plant items.
Objects that were faked to look like plants also triggered a slow response time.
The authors concluded that trial and error across centuries of human existence had taught infants to be intrinsically wary of physical contact with plants.
“We are not suggesting that infants are actively afraid of plants,” Dr Wertz and Dr Wynn concluded.
“Rather, we propose that once infants identify an object as a plant, they deploy a behavioural strategy of inhibited manual exploration, which serves to help protect them from plants’ potential dangers.”
For parents who have been noting this “behavioural strategy” every time they attempt to spoon some peas into the mouth of their child, this finding should come as a welcome relief, they said.
Posted by jonjayray at 12:32 AM