myopia

Ultraviolet radiation and myopia

Ultraviolet radiation and myopia 2

I feel like writing another article about the possible benefits of something we’ve all heard is bad for us. Ultraviolet radiation (UV) sounds bad. Maybe because of the word radiation (not a bad word though) and then maybe all the news warning us about UV exposure. I’ve had many sunburns and believe it’s contributed to a couple of skin problems I’ve had so I believe the redness and pain associated with sunburns is a pretty obvious sign of too much sun. As a kid in the 70’s I remember putting zinc oxide on my nose. It was a thick bright white cream that definitely was noticeable. I wish I had a picture of that when I was sitting on the lifeguard stand watching all the other kids get their UV (and chlorine) exposure at the pool.

You’ve got to wonder though how our species ever survived with that constant stream of the suns rays just bearing down on us all the time. Scientists have divided up that UV band of radiation into 3 forms….A, B and C. A is the least harmful and C is the worst but C doesn’t even reach us because the atmosphere’s ozone absorbs that band. Why did we even call it UV-C if it doesn’t reach us? We can create UV-C ourselves through welding however. See the chart at the end showing the UV ranges.

One huge benefit of UV exposure is our body uses it to produce vitamin D. We can also get vitamin D from other sources and you’ll find plenty of foods supplemented with vitamin D. That just makes me wonder why all the news about vitamin D deficiency. I have read that too much UV-B exposure can actually destroy vitamin D production but that article I read didn’t say if that was 1% destroyed or 100%. That’s what bothers me about some of the information we get unless you dig further in the research. And this is where I think some organizations have gone too far with their warnings. They make the sun sound like it’s horrible! Too much of anything isn’t good for you but articles talking about avoiding UV just seem wrong. Life wouldn’t exist without it. Too much vitamin D supplementation isn’t good either….that’s toxic. Do they talk about that? Rarely. Instead of warnings, we should talk about moderation.

Here’s another thing I’ve been interested in regarding UV radiation. Most of the contact lenses I prescribe have an FDA approved UV blocking agent in the lenses. I don’t know when that all started. Since I don’t wear contact lenses and neither do most other people, will those that wear these UV filtering contact lenses be better off than the rest of us? And then there are glasses that have UV protecting effects. Will people that wear glasses be better off when the results of UV accumulation over a lifetime are more obvious regarding diseases attributed to UV exposure? I do wear sunglasses outside….sometimes. Most sunglasses, even cheap ones, block practically all UV radiation and our car windshields block that as well. I’d like to know how I can measure my lifetime UV exposure. Have I exceeded it? How can I possibly know if I have a little left over so I can go play outside?

But there’s one more thing that is interesting about the possible benefits of UV exposure…in children. It’s thought that the outdoors might provide some protective effects against myopia development. That means some very credible studies are finding the sun is good for kids. There’s even at least one study that shows that UV exposure may provide a certain protective effect against myopia. Instead of “protective” can I say benefit?

I say get outside and enjoy whatever weather you’ve got. Put down the ipads and back off the consoles and let me put up a permanent basketball goal at my house! The kids need to be outside more!

Here’s a study about UV and myopia.

http://www.ncbi.nlm.nih.gov/pubmed/22669720

 

UV graphic

UV graphic

 

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Myopia confers protection from diabetes

Myopia confers protection from diabetes 0

The title isn’t clear. Here’s what I mean. If you have myopia, some studies show that you are less likely to get diabetes or you are less likely to have significant diabetic problems. With all the bad things that can happen because a patient has myopia, I can see how the good things might not be reported or seem important. Let me be clear though, having myopia doesn’t mean you won’t get diabetes. It just means you are less likely.

Myopia is also called nearsightedness. It’s not something I have but it’s the most common reason for patients to come to my office. They want glasses or contact lenses usually. That’s mainly why I have a job….people need optical correction to correct their vision. My job is also to check for eye diseases. Those with myopia are at a LITTLE greater risk of some problems and more so if the myopia is high (greater than -5.00). The other guys…the hyperopics (those that are farsighted) have their own¬†LITTLE¬†risks for certain conditions. The other common vision problem easily corrected is presbyopia and I don’t know of any diseases associated with that condition other than losing your reading glasses.

Let me clear up what I mean by risk. If you read a research article and it says the odds ratio for some condition is greater than 1.0, then the risk is higher. If the risk ratio is less than 1.0, then that person is less likely to have/develop the condition than the other group in the study. If the odds ratio is 2.0, then that means twice as many people with myopia will develop that problem than the other group in the study.

In one study I read, a highly myopic person was less likely to develop what’s called proliferative diabetic retinopathy (PDR). Let’s just say, you don’t want to have diabetes AND PDR, period. The odds ratio of having PDR for a younger high myopia person with diabetes was 0.40. That’s lower than 1.0 which means they are less likely of getting PDR. What’s interesting about this is that those with high myopia are at a greater risk for other kinds of retinal problems but in this case, they are at less risk of PDR. It might have something to do with the vascular differences the study said and the extent of a condition called posterior vitreous detachment.

There’s another odds risk for those that have myopia and the likelihood that they will even get diabetes. It was reported as 0.90. That’s less than 1.0. So myopics were less likely to get diabetes compared to the other nonmyopic group in the study.

I should tell you what those bad things are that are more likely to happen in a myopic patient though. The odds ratio varies around 2.0-3.0 for these conditions compared to those with no myopia:

retinal detachment

glaucoma

PSC cataract (that’s not the typical age-related kind of cataract)

macular disease

So, just come in and let me look or get your eyes checked wherever you are. You’re probably fine but you myopes do have a LITTLE greater chance of me finding something there that isn’t good.

I am getting (or have) the complete articles below if anyone wants them.

http://www.ncbi.nlm.nih.gov/pubmed/20031224

http://www.ncbi.nlm.nih.gov/pubmed/8302567

http://www.ncbi.nlm.nih.gov/pubmed/22772022

myopia example

myopia example

 

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