Wednesday, June 1, 2011

Cataracts

An article I couldn't sell:



Cataracts

“Why should I read this?  Cataracts only happen to old people!”  Yes, but there are steps that you can take now so that they don’t happen to you when you get old—or at least, don’t happen to you until you are very old.  I am 54, and at my last ophthalmologist appointment, my doctor noticed that I am just beginning to get the first signs of cataracts—a slightly yellowing of the lens.  

Over time, this change goes from yellowing to a blur.  When you get old, or very old, the solution often involves removing the lens, and replacing it with an artificial lens.  It is not a particularly difficult or risky procedure (in spite of the fact that someone is cutting into your eye), but all things considered, I would prefer not to have this done if I don’t need it—and I would prefer to put it off as long as possible.  I’m a wimp—I prefer not having people with sharp objects going after my eyes.  Also, I am pretty sure that this procedure isn’t free, and I am a hopeless cheapskate.

What causes cataracts?  There are a number of causes.  Ionizing radiation, such as you get from nuclear weapons detonations, reactor accidents, and being someone who uses X-ray machines for a living, is an established risk factor.  I would recommend that you not purchase your own personal nuclear reactor if you want to avoid cataracts, and setting off fireworks in the kiloton range and above is definitely not a good idea (at least, don’t do it every month). Airline pilots are also at increased risk, apparently because of cosmic radiation exposure at high altitudes.  

There’s not much you can do about cosmic rays, nuclear weapons, or reactor accidents, so let’s look at something that you can control: ultraviolet light.  Ultraviolet light comes in two frequency ranges: UV-A (400 – 315 nanometer wavelength) and UV-B (315 – 280 nm).  The evidence is quite clear that UV-B increases the risk of cataracts.  A study of those working on Chesapeake Bay (who get a lot of UV exposure both directly and by reflection from the water) found that “doubling of cumulative exposure” increased the risk of one type of cataract “by a factor of 1.60.”  This was a statistically significant increase.  Similar studies elsewhere show this same relationship: the more UV-B exposure, the more risk of cataracts.

You could stop going out in daylight, and stay away from tanning salons, but unless you are planning to go vampire, this is not particularly practical.  What you can do is reduce your exposure, by wearing sunglasses—and specifically, sunglasses that block UV-B.  While some prescription glasses have a UV coating on them, it is less effective than sunglasses made specifically for that purpose.  The other problem with conventional glasses—and even many sunglasses—is that they do not provide protection from the sides.  This is especially an issue since the current fashion is no longer the enormous lens that were popular back in the 1970s (and which I still wear, since I am trapped in a disco time warp), but tiny lenses that remind me of what John Lennon used to wear.

There are several UV standards for sunglasses: the European standard EN 1836:2005 defines the amount of UV that passes through a lens.  If no more than 5% of 380 nm light passes through, it conforms to what is popularly called the UV 380 standard.  You will also see the UV 400 standard, which is much like UV 380, except measuring 400 nm light.  (UV 380 would be a better choice than UV 400, since 380 nm is shorter and more powerful than 400 nm.)  The U.S. standard ANSI Z80.3-2001 allows no more than 1% of UV-B to pass through the lens.  

As I mentioned, you really want something that wraps around the eyes, so that you are not getting UV-B exposure through the sides.  I bought some of these because they had polarizing lenses, had the wraparound protection, and slipped over my existing prescription sunglasses.  I wear them as consistently as I can when driving or when I am outside—but especially when there is snow on the ground.  (Snow reflects UV so well that it can double your exposure.)  My wife thinks I look like a geek when I am wearing them, but if I can delay cataract surgery five years—or even better, never need it, who cares what I look like?

2 comments:

Paul Sand said...

The "some of these" link is bad. I'd like to check them out, because I already look like a geek, so the extra geekiness would be marginal. Right?

Clayton said...

Fixed the link.