Do you wear glasses? 

Then what about eye lenses?

Ahh i get it i get you've done the eye surgery thing!

If by any chance you don't have an eye issue then you are very lucky my friend. Nearsightedness or Myopia is the most common eye issue among humans. it is estimated that over 42% of Americans between 12-54 have Myopia. Also the ones that earn the first spot in Myopia are East Asians with a socking 69% at 15 years of age. Chances are that if you live in a village and in general a rural area you are luckier in terms of Myopia than those who live in big cities. Before we get to the main issue i can't help it but mention that according to this study by 2050 more than 50% of the world population will have Myopia.

Do I Have Myopia?

Before we start explaining what Myopia is we first need to see what are the signs that gonna make you understand if you need to concern or not. If you haven't Myopia then you shouldn't care much about that post as there is no point other than to just gain some extra knowledge. The top sign to understand if you have Myopia is to just not see clearly the show you are regularly watching in Tv or Pc or the subs. In general you won't see clearly some road signs and you gonna face difficulties seeing distant objects,faces and letters. 

On the other hand a good thing is that you can pretty much watch everything that i close to you and read for your school, college or for your own entertainment. If you have high Myopia then you may find some difficulties in reading too but it won't be much of a deal. The rule is the closer the better when we are talking about that kind of issue. Also another minor sign is if you have headaches while as we said you find out that you can't see as good as you used to. If that's the case then you need to visit a doctor and to be more exact an optometrist or ophthalmologist.

Don't worry you are not gonna hurt. The ophthalmologist will just make some tests and will check your eyes closer to measure if you have eye issues and how much Myopia you have. A funny test is when he/she will tell you check some numbers and letters and tell them him/her. the result if you have Myopia will be really funny as the letters and numbers start from big one and end up really tiny. An A maybe an E in your eyes, a 5 can be and 8 and A X maybe nothing at all!

How is Myopia caused? 

For better explaining it we need first to learn what the retina and the cornea is. Below of the terminology i have a picture for better understanding and to realize where exactly in our eyes they exist. 

Retina: The Retina is a sensory membrane that is located in the inner tissue in the back of the eye. It has a bunch of different layers and in a particular one we can find the photoreceptor cells that can further divided in rods and cones. Rods can detect motion and provide us with the black & white vision while Cones cover a broader variety that of color vision and their performance is better in bright light. 

Cornea: The Cornea is the front surface of our eyeballs that anyone can see. it is responsible for allowing the light to pass through and has 5 layers too. Except a light entrance the Cornea plays another big role and that is that provides about 65-75% of our eye's focusing power. 

source

We finally came to the part of answering the big question of how Myopia is caused. Basically what's happening is that light falls in a wrong way onto the retina. the retina as we mentioned through it's photoreceptor cells that can react to color and sent that information to our brain don't do that and that's why we can't see clearly. Now this one has an explanation to it too. Our eyeballs are too long comparing to the focusing of the cornea so the light is focusing only to a certain point onto retina and not the whole surface. There is also a chance that the cornea might be to curved for the length of the eyeball.

So what your doctor does is finding the correct lenses either this is glasses or contact lenses that can fit you new shaped-changed eyeball or he/she gonna suggest you an eye surgery than can alter the shape of your lens!

A Funny Trick To See!

As a bonus i will show you a funny little trick i found over the internet that can make us see a little bit without using glasses and contact lenses. All we need is only our bare hands. First of all take of whatever you use to see better ( well after you read the next part :P ), make a tiny hole with your hand and now look through it a distant object. For better results use only an eye and a hand pet time not both hands and eyes and set a goal to see a distant photo,object or to read something that is a bit far. If you still don't see any improvement try to make the hole a bit smaller. 

I bet you have seen a bit clearer don't you?

Great! Now let's explain how this whole thing is happening. The whole big deal of the trick is the tiny hole you created with your bare hands. As light is everywhere and travels everywhere by creating this hole we limit the amount of light entering our eyes and retina to small percentage and space. So now light can only travel through one spot and not many different ones. At the same time when light travels through a small space it's easier to be focused from anywhere.   

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sources
http://www.allaboutvision.com/conditions/myopia.htm
https://nei.nih.gov/health/errors/myopia
https://www.nature.com/news/the-myopia-boom-1.17120
http://onlinelibrary.wiley.com/doi/10.1111/opo.12130/epdf
http://eyewiretoday.com/2016/06/21/nearly-10-million-adults-found-to-be-severely-nearsighted-in-the-united-states