I am not even 20 and my vision is getting progressively worse. what can make vision worse?

Heredity : If you are nearsighted, as long as you are still growing your eyes will be growing as well causing more nearsightedness. Also, extensive reading or computer work will cause a temporary change as well. There is a rare form of progressive nearsightedness that never stops changing. Astigmatism rarely gets worse without underlying corneal problems which should be investigated with corneal mapping.