How does eye strain affect the length of the eyeball?

[BHL 20]

Ever since I learned that short-sightedness is due to the eyeball being too long, and far-sightedness is due to the eyeball being too short, I've wondered what the point of avoiding eye strain is. How could straining the eyes possibly have the effect of changing the length of the eyeball? By strain I mean both trying to see things very far away and close-up; and the continued use of eyes when they are tired.

 

[Doug Huffman]

While there may be a correlation, the usual cause attributed to such is age related. Muscle stress may be essential to proper function of the muscle, including muscles of the eye.

You do know that strain is dl/l?

 

[jollyunclejoe]

Ever since I learned that short-sightedness is due to the eyeball being too long, and far-sightedness is due to the eyeball being too short, I've wondered what the point of avoiding eye strain is. How could straining the eyes possibly have the effect of changing the length of the eyeball? By strain I mean both trying to see things very far away and close-up; and the continued use of eyes when they are tired.

I think Doug is correct, myopia often develops with age. As far as I know, normal eye strain (simply focusing on objects for a rather long time) won't damage the eyes or change their anatomy in any way. Apparently however, straining on distances at short range (aka a computer screen) can result in the eye to lengthen and thus near nearsightedness to progress, but I wouldn't know if that is for sure . If it is, then I should probably get off of the internet so I don't become blind.. Hope this helps.

 

[Andy Resnick]

Ever since I learned that short-sightedness is due to the eyeball being too long, and far-sightedness is due to the eyeball being too short, I've wondered what the point of avoiding eye strain is. How could straining the eyes possibly have the effect of changing the length of the eyeball? By strain I mean both trying to see things very far away and close-up; and the continued use of eyes when they are tired.

Eyestrain appears unrelated to the shape of the eyeball- it seems to be fatigue in the muscle that controls blinking:

http://journals.lww.com/optvissci/A...ed_Pain_Induced_by_Visually_Demanding.13.aspx