What can cause nearsightedness?

im in 7th grade,and have to wear glasses since 2 years ago because i cant see words that are written that are more than 5 ft. away (but i can see people far away very clearly),but anyway i was wondering what can cause this because no one in my family wears glasses for nearsightedness so its not heredity.

i wear my glasses most of the time,but i take them off when im reading because it gives me a headache and i take them off when i dont need to read stuff on the teachers chalkboard or something like that.

I'm myopic, and have to wear glasses too. I can see people but details are difficult for me.

Sometimes straining your eyes too much can make it worse, like trying to squint more to see.

Also, do you regularly wear your glasses? When I was in high school, I would take them off sometimes because I didn't like them but it made my eyes worse and then had to get a stronger prescription.

Just some thoughts.

Sitting too close to the tv


Or genetics!

If you've been on the computers for 24/7.

I was the middle of 5 kids, and the only one blind as a bat. Nearsightedness is caused when the eyeball itself is slightly too long (think oval). The image cannot focus properly on the retina, so it is fuzzy. Next time you see your eye doctor, get them to explain it to you. When you are old enough (and I mean probably in your 20's), you can get lasix to correct the vision. In the mean time, there are some pretty cool frames out there, or even cool contacts you can wear.