You'd think this one would be simple for a guy like me who has worn glasses since the third grade, but it's so much a part of my life that I rarely think of it. We all know people who have bad vision, but there are ways of mitigating the issue that were not widely available during previous eras. Why is it then that we rarely read about a character who is deficient in this way (unless they are very old, generally used for comic effect)? Where is my near-sighted hero?
After doing some research, it seems that the rate of myopia (nearsightedness) is significantly on the rise. According to the National Eye Institute, cases in adults aged 40+ increased by more than 10% from 2000-10. A TIME Magazine article from 2012 suggests that up to 90% of Asian schoolchildren suffer from myopia (though it's only 20-30% of schoolkids in the UK). Unfortunately, it's very difficult to ascertain the prevalence of this issue historically.
There are a few theories about the causes of nearsightedness. The first suggestion is that it is a result of doing "close work" (think of a tinkerer bent over his workbench, or You right now) and the related eye strain. It's why my mom always used to tell me to turn on more lights when I was reading (ok, she still does). This theory in general has been discounted, though it may be connected to the root cause.
The second theory is closely related to the first, but suggests that our eyes don't get the stimulus they've grown accustomed to over the evolution of humanity with various depths of field and such. Sitting indoors under steady fluorescent light provides little challenge to our system. Since modern humans don't make the eyes work as much, they do not develop at the rate of our ancestors'.
A more recent theory suggests that (in children) myopia may occur due to a lack of exposure to daylight which could limit eye growth. "Our hypothesis that the mechanism of the effect of light was mediated by retinal dopamine, a known inhibitor of eye growth whose release is stimulated by light, has also been supported by animal experiments." (CNN 6/1/11) In other words: an increase in retinal dopamine, brought on by sunlight exposure, is a signal that the body is trying to control eye growth (it was an interesting quote to interpret). That almost sounds scientific!
Any of these reasons would explain the images I have of nearsighted monks wandering monastery halls. It was long thought that myopia was genetically tied to intelligence (because they often appear together), but poor vision seems to simply be a byproduct of spending too much time indoors reading. Apparently, these connected conditions are part of the problem science continues to have in trying to determine a true cause (though naturally there may be more than one).
To return to my initial question, I think the reason for the lack of my bespectacled hero is obvious (no, Harry Potter doesn't count). Most humans during the pre-industrial period got plenty of sunlight and stimulation. It does lead one to wonder what would happen to miners or dwarfs who might spend most of their days underground. Hmmm maybe the dwarfs would pull a Daredevil (the Marvel Comics character, silly) and acquire other senses more acute. Ah well, I guess the monocles and pince-nez will remain in steampunk.
http://en.wikipedia.org/wiki/Myopia
http://www.nei.nih.gov/eyedata/myopia.asp
http://healthland.time.com/2012/05/07/why-up-to-90-of-asian-schoolchildren-are-nearsighted/
http://www.cnn.com/2011/HEALTH/06/01/myopia.causes/
No comments:
Post a Comment