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The Biomedical Engineering blog is the place for conversation and discussion about topics related to engineering principles of the medical field. Here, you'll find everything from discussions about emerging medical technologies to advances in medical research. The blog's owner, Chelsey H, is a graduate of Rensselaer Polytechnic Institute (RPI) with a degree in Biomedical Engineering.

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Don't be Myopic About Going Outside

Posted April 17, 2015 12:00 AM by Chelsey H

I got my first pair of glasses when I was 14 years old because I couldn't read the board from the back of the classroom. I remember walking out of the store and being surprised that I was able to read the names of stored across the parking lot - I didn't know I should have been able to see them.

But I am hardly alone in needing glasses, and nearsightedness is reaching epidemic status. More than 2.5 billion people around the world will have myopia by 2020. This problem is especially prevalent in China, where 90% of teenagers are nearsighted.

Myopia, also called nearsightedness, is caused by a slightly elongated eyeball, which means that the light is focused just in front of the retina instead of on it. The danger of myopia comes when the deformation stretches and thins the inner parts of the eye, which increases the risk of retinal detachment, cataracts, glaucoma, and event blindness. Image Credit

A recent article in Nature magazine (very interesting read) points to an interesting hypothesis behind the cause of all the nearsightedness: kids are staying indoors for too long these days. The hypothesis is based on several studies showing kids who spent more time indoors had a higher risk of developing myopia. And before you get to bashing computers - it's not the lack of physical activity that's causing the problem, it's the lack of exposure to bright light.

The eye grows throughout childhood and outdoor light promotes eye growth. One researcher encourages kids to spend at least three hours a day exposed to bright light - the equivalent of sitting under a tree wearing sunglasses.

Unfortunately, if you're already nearsighted it's too late to fix it with sunlight. But going outside is probably good for you anyway.

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#1

Re: Don't be Myopic About Going Outside

04/17/2015 2:51 AM

I'm far sighted, I guess I spent too much time outdoors.....

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#2

Re: Don't be Myopic About Going Outside

04/17/2015 8:27 PM

I started needing glasses by age 10. Prescription got progressively worse until my mid-forties when it topped out at about -8 on both sides. It's getting better now, down into the minus sixes and I am 52 now.

I was very much an outdoor kid and adult. Very little time spent indoors, so I don't think there is that much to this hypothesis.

My dad had a similar situation. As he got older, the nearsightedness diminished to the point where he didn't need correction to pass the eye test for driver's license. Since he just recently had cataract surgery with lens replacement, he now has perfect distance vision and wears glasses for reading.

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Re: Don't be Myopic About Going Outside

04/20/2015 9:45 AM

The change in your dad's eyesight after cataract surgery is exactly the same as a friend of mine experienced. I was really surprised that the surgery not only allows her to see clearly but it also allowed her to ditch her bifocals and use only reading glasses when she needs them. Did your dad's opthamologist offer any insights (pun accidentally intended)? Maybe when/if I have cataract surgery I can ditch these glasses I've worn since I was 4.

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Re: Don't be Myopic About Going Outside

04/20/2015 10:53 AM

Yes, absolutely. Talk to your ophthalmologist. The replacement lenses can be selected to correct your vision to near perfect (single prescription). There are multi-focal lenses available too but not everyone is a good candidate for that as there is some brain training required to get used to them. They are also looking at replacement lenses that allow the eye's muscles to 'adjust' for reading and then relax for distance, but those are still very much in the developmental stages.

Although I wear contacts for distance vision and then reading glasses for close up work, I won't have anybody cut on my eyes until I HAVE to. At the point in which my eyes develop cataracts, then I will make that jump. And I figure by then, the technology will have improved. the longer I can put it off, the better.

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#3

Re: Don't be Myopic About Going Outside

04/18/2015 10:17 AM

I'm nearsighted in one eye and farsighted in the other. Not sure what that means.

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Re: Don't be Myopic About Going Outside

04/18/2015 4:23 PM

I suggest you stop peering out through the keyhole :)

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#6
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Re: Don't be Myopic About Going Outside

04/18/2015 9:24 PM

Did you play outside a lot?

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Re: Don't be Myopic About Going Outside

04/18/2015 4:29 PM

There is a contradiction in the logic here:
1. Myopia is caused by an elongated eyeball.
2. Outdoor light promotes eye growth.
3. Kids who spent more time indoors had a higher risk of developing myopia.

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#9

Re: Don't be Myopic About Going Outside

04/22/2015 11:03 AM

I'm another who got his first pair of glasses as an early teen (13). Near-sighted due to lack of bright light? Then why am I so familiar with dermatologists now? I spent so much time in the bright Texas sun getting blistering ultraviolet radiation burns during the first 20 years of my life that I have had to have things scrapped from and cut out of my skin every year for the most recent 20 years of my life.

Of course, my story may be like the "but I know someone who was thrown clear" type of rebuttal of the safety value of seat belts. But the increase of myopia coinciding with the decrease of outdoor activity does not, in itself, indicate a connection between the two.

I need to read the links and see what they have to say.

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Re: Don't be Myopic About Going Outside

04/22/2015 11:51 AM

After reading the articles, I have several questions, which I should ask an ophthalmologist, I suppose.

First, myopia is from elongated eyeballs. In all cases? what is the "normal" length? (mean and std dev) How many std dev longer than the mean indicates myopia?

Second, when myopia is diagnosed, is length of eyeball measured in every case? Not calculated or inferred, but actually measured?

Third, the lens focuses the light on the retina. Is all myopia due to length of eye, or are factors surrounding the lens subsystem also causes? Eg, lens pliability. Muscle strength.

Here is my take: Given (from past reading, which I may document later) the normal state of the lens system is resting, with muscles relaxed, and focus set at far. Given, near vision requires lens muscles flexed and lens at max distortion from resting state. Hypothesis: Prolonged indoor activity forces the lens system into an attitude from which it may not fully relax, even when trying to focus on far. Result: increasing incidence of myopia.

That is, the "far" of outdoors is much different than the "far" of indoors, so the system calibrates itself to the indoors "far".

But I really, really, want to know if all myopia is from the focal point falling in front of the retina because the eyeball is too long, or if it can be because the focal system is defective.

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#11

Re: Don't be Myopic About Going Outside

04/22/2015 11:52 AM

From the Nature article:

"Ian Flitcroft, a myopia specialist at Children's University Hospital in Dublin, questions whether light is the key protective factor of being outdoors. He says that the greater viewing distances outside could affect myopia progression, too. "Light is not the only factor, and making it the explanation is a gross over-simplification of a complex process," he says."

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