Posted by garnet71 on March 26, 2009, at 7:49:00
In reply to Re: To Larry H. - epidemiology info. question » garnet71, posted by Larry Hoover on March 24, 2009, at 13:17:01
"The prevalence of myopia shows a decline with age in cross-sectional studies. This pattern may represent an increase in the prevalence of myopia in younger generations, possibly through increased exposure to near work, or an intrinsic age-related decline in myopia prevalence"
I haven't had enough motivation yet to pull up that article and grasp its findings, so I wasn't going to comment yet..but...
Do you trust that NHANES and other H&HS data when comparing a timespan? They changed their methodologies for many of their data collections in several areas, I noticed. I looked at the drug rates for U.S. youth, and at the time when they changed their methodology (if you read the small print), substance abuse has declined and sort of held steady at the declined rate ever since. They have a whole section that describes the methodology and explains how they adjusted for it. I didn't actually read all that, but it is suspicious that youth drug abuse has declined at the very time they changed data collection method, even after adjusting for it.
So I looked at other H&HS data--for substance abuse hospitalizations to see if trends could be established that way. There was no consistency, so there is really nothing to compare over decades.
I was hoping there were some university studies seperate from the govt ones, but it appears all the researchers use the same govt. data. I did find one university study but it only covered a small time period. Well, if drug use has declined like they say, that would be great. I just don't trust their numbers but hope they are accurate.
For the myopia rates, that study doesn't seem to indicate the increases in youth and excludes those under 20. I need to retrieve the article though.
It's suprising this hasn't been tracked in the U.S. since those studies in the 70s and 80s. For the articles I skimmmed about Asian rates, I saw various theories as to why myopia rates are increasing, besides genetics, such as:
- spending more time studying
- lack of natural light
- lack of outdoor activity
- diet - increase in processed foodsOh, I also came across an article that links a pesticide with vision problems. Can't remember where i found that.
I forget what else. It would be interesting if someone studied myopia rates in to those countries where children go to school all summer long vs. those like the U.S. where kids have off in the summer.
Anyway, its very difficult to look at trends over the past 15-20 years in an aggregate manner with lack of data consistency considering what's available, thus it would be difficult to project future trends.
I love looking at trends and evolutionary changes. "Predicting the future" has a lot of utility in many ways, I think. And if someone was a diehard entrepreuner, if they would have caught the trends in Asia, they could have capitalized upon the eyeglass and contact markets in Asia considering almost all children in some areas need eyewear. Should have bought stock in that industry years ago...lol I wonder if that's the type of industry where there is just a few large manufacturers, or whether there are many small ones. Maybe different in Asia. Eyeglasses are so much cheaper there in the U.S. I wear contacts most of the time, but have glasses too. Last time I bought them a couple years ago, they were $350. I can't see good and need new ones, but can't afford to buy them. I have nice fake Prada frames from China too, just waiting to have lenses inserted in them..lol. The frames are going to go out of style by the time I can get them.
Anyway, thank you very much for finding that.
poster:garnet71
thread:886785
URL: http://www.dr-bob.org/babble/20090322/msgs/887057.html