Hi, again! Back being a Mr. Wizard wannabe with little-known facts about AMD, your eyes, light and all sorts of weird stuff. This is kinda fun! I started looking for the stuff about altitude and AMD and stumbled upon more cool facts about UV light. Thanks to the National Weather Service, Flagstaff.
Ultraviolet – or “beyond violet” because the wavelength is even shorter than violet light, the shortest wavelength light we can actually see with our eyes – is generally reflected or absorbed by the ozone layer. However, there is plenty of UV light that gets through. This UV light can get through to us either directly or in a diffuse manner. Because ultraviolet, violet and their other, short buddy, blue, are so small, they get pushed around more than the other lights. The sky is blue because all the short-stuff rays are being pushed around up there. Violet and ultraviolet are there, too, of course.
Being small and doing all that bouncing around mean ultraviolet is more stealthy. It slips through in “sky shine”. It also slips through on overcast days. That means we need to be even more careful and wear our sunglasses when it is overcast.
And speaking of sunglasses, I discovered why they say sunglasses are good for ultraviolet and then a letter. Ultraviolet has parts A, B and C. UVC is the bad stuff. It is a danger to both plants and animal. 99% of ultraviolet UVB is absorbed by the ozone layer. The 1% that reaches the ground can potentially cause damage at the molecular level. UVA fades things and makes things brittle.
So that is the science lesson on UV light. Now it is time to move on to the effects of altitude. Or, more precisely, high altitude hypobaric hypoxia. Huh? You know, low air pressure, low oxygen conditions like you get on, oh, for example, Everest or K2.
Back in 2005 a group of researchers working in Nepal published a study in Ophthalmologica on macular changes at high altitudes. They only studied three people, all of them experienced climbers. All three showed macular changes for the worse. The authors concluded AMD folks should avoid high altitudes without proper acclimation.
In 2012 Grimm and Willman published a study again on hypoxia and retinopathy. They determined low oxygen can lead to the expression of vascular endothelial growth factor.
When you think about it, it makes sense. The eye is actually an energy hog. Energy production requires oxygen. If your eye is low on oxygen, it may try to get more by building more “supply lines”. That is what blood vessels are; yes, no? Our bodies are actually pretty smart.
From the little research I did, it would appear there are some reasons for concern when traveling in high altitude locales. However, provided you are not attempting an ascent of Everest, the effects are not so bad they cannot be mitigated.
It would appear good quality sunglasses are a must in such environments. It would appear from the research that proper acclimation to the altitude is also a must. Give your body time to become more efficient in getting oxygen where it needs to go.
As I have said numerous times, I am not a doctor. These are just educated guesses and precautions that I, as a fairly intelligent person, would take. Remember to check with your doctor for all medical advice. Your retinologist should be your guide.
(And if you are in Nepal, greetings! My puppygirls just realized you had Kukur Tihar, the day of the dog celebration, November 6. They think any people who have a day set aside to honor dogs are just great!) [Since Sue & I are both ‘dog people’ she thought it’d be cool to show a photo of a dog on that day. At my house, every day is The Day of the Dogs! ::smile::]
Written November 17th, 2018
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