Evolution of eye sight and huge need of glasses?

Question

I have been thinking about this problem for a long time. It is more than often said that eye sight is perhaps the most important sense of human beings. However, it is a very high percentage of people who need glasses and would have a hard time without them.

Why is myopia so extremely common? One could think that such important sense as eye sight would have evolved perfectly but it hasn't.

I also heard of a documentary that suggested that "modern eyes" don't get enough practice in today's environment. Thus, people suffering of myopia should, according to the documentary, wear in fact convex ("plus") lenses to train the eye.

I would love to know why so many people need eye glasses. And please feel free to post any relevant links on the topic. Thanks so much in advance!

Thanks for the comment #1. Just to add sth since I think I didn't quite stress the main idea of my question: I would like to know what biologically (no matter what the "spirit or intelligence" is behind all this, it could be evolution or not) makes the human eye so dependent on eye glasses. What has changed in the history? Is it genes or just daily life that requires different things from the eye muscles?

Answer 1

I am an MD. I have wondered about this very question alot myself. I believe it has possibly at least several different explanations. First, there is a study that has shown that infants and toddlers that are exposed to the outdoors alot, especially to daylight during the very early years are far less likely to develop myopia or nearsightedness. It seems that the periphery of the eye needs sunlight or daylight to develop properly, and without this, we encourage myopia. Since we have only recently transitioned from an "outdoor species" to an "indoor species", evolution has not had any time to correct this problem.
The second thing is that we live roughly twice as long as chimpanzees, and also twice as long as our chimpanzee common ancestor, we presume. When we humans grow older than roughly 40-45, even people with perfect vision become unable to see things close up. This is called "presbyopia" and is considered a normal part of aging. However, a touch of nearsightedness greatly ameliorates this problem without the use of corrective lenses. Myopia may be a positive adaptation to our very recently evolved longer life expectancy.
Anyway, it is fun to think about.

Answer 2

I suspect that part of the answer could be, the lack of natural selection we encounter is allowing those with poor vision to live far longer and to reproduce propagating poor vision.

Also, I suspect, we have far more awareness of vision problems and far more access to testing to make the bad vision determination. 20 to 50 years ago, many people may have just lived with mediocre vision as it was adequate to get through life. But, more recently with in-school testing and more emphases on healthcare, more people are made aware of their vision issues. So, it seems like there is a disproportionate number of people requiring glasses, but in reality, it's always been this number.

It could be similar to breast, prostate, and colon cancer. It seems like the numbers keep going up, but I suspect we are just better at testing, and test more often so we get the appearance of higher numbers when in fact, the numbers may be going down.

Answer 3

Do you really believe in evolution? It just seems so far fetched to me? I agree that we all evolve but i deny that we came from some sort of oze. By the way, and I apologize for not having the specifics with me, the author, along with a lot of other very liberal professors, of the very text book that college's use to teach evolution has made the statement that he was not taught the truth and his own textbook is wrong. They no longer believe in evolution. They say that life is too complex to have just happened to happen. Intelligent design.