When nearsighted (myopia) you do not see well in long distances. The eye is too long in proportion to the eye's refractive ability. The picture of a remote subject is front of the retina. But with a concave lens you move the sharp picture backwards to the retina.

when long-sighted (heperopia) you cannot see well in a close range. The eye is too short in proportion to the eye's refractive ability. The picture of a remote subject is front of the retina. But with a convex lens you move the sharp picture forward to the retina.

Astigmatism can exist independently if you are nearsighted or long-sighted. The cornea is when not symmetrically, which makes the light refracting asymmetrically. Therefor a sharp picture is not created on the retina. Regular astigmatism can be corrected by a cylinder lens.

By presbyopia you cannot see sharply in the close range. In old age the eye's ability to accommodate decrease. Presbyopia usually starts in the 40's. Reading glasses helps against presbyopia.