Can doctors tell you what causes poor eyesight?

Yes: Vision requires the proper focusing of light coming into the eye, the conversion of that light into an electrical signal, and higher order processing of those signals by the brain. Alterations along this pathway can have an impact on vision. An ophthalmologist (a medical doctor who has specialized training in the eye) can perform an exam and tests to evaluate the reason for decreased vision.

Poor Eyes: There are many causes of poor eye sight. One is poor nutrition, since a healthy diet is important for eye and overall bodily health. Another is prolonged near work without a break-- make sure to take a break every 20-30 minutes when reading or using a computer-- take time to look at something far away out the window to relax your focus.