In order for an object to be seen clearly, its image must come to a clear focus at the central region of the retina, called the fovea. Myopia or nearsightedness, in which images are focused in front of the retina. Myopia is corrected by a concave lens that causes light rays to diverge before striking the eye.
Hyperopia is corrected by a convex lens that refracts light rays before they strike the eye.
Presbyopia , is a condition that occurs as one ages, in which the refractive power of the lens diminishes. The effect is that objects near the eye cannot be focused. Repeat this procedure with the left eye and repeat with both eyes open. If some groups of lines appear blurred or lighter in color, this indicates that astigmatism is present. Repeat with the right eye.