Refractive errors include myopia, hyperopia, presbyopia, and astigmatism. Most people have one or more of them. Refractive errors can usually be corrected with eyeglasses or contact lens.

Myopia (nearsightedness)

If you have myopia you can clearly see close objects, but distant objects are blurry. Myopia is caused by the eyeball being too long. Myopia occurs in different degrees from minimal to extreme. The more myopic you are the blurrier your vision is at a distance and objects will have to be closer to you so you can see them clearly.

Hyperopia (farsightedness)

If you have hyperopia, you can see distant objects clearly, but close ones are blurry. Hyperopia occurs when the eyeball is too short for the light rays to focus clearly on the retina.

Astigmatism

If you have an astigmatism, the surface of the eye (cornea) is not perfectly round, rather it is more oval and doesn't allow the eye to focus clearly. The cornea is very important in helping the eye focus light rays on the retina. Astigmatism rarely occurs alone, and is usually accompanied by myopia or hyperopia.

Presbyopia

If you have presbyopia, you have trouble focusing up close. Presbyopia occurs as you age. Most people are between 40 and 50 years when they realize for the first time that they can't read objects close to them. The letters of the phonebook are "too small"or you have to hold the newspaper further away from your eye to see it clearly. At the same time your ability to focus on objects that are far way remains normal.

Here is what you see with normal vision:

Here is what you see if you have a refractive error. The image appears blurry at a distance if you have myopia or it is blurry close up if you have hyperopia or presbyopia.