Refractive errors include myopia, hyperopia, presbyopia, and astigmatism, eye conditions that are very common. Most people have one or more of them. Refractive errors can usually be corrected with eyeglasses or contact lenses.
What is myopia (nearsightedness)?
If you have myopia you can clearly see close objects, but distant objects are blurry. Myopia is usually 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.
What is hyperopia (farsightedness)?
If you have hyperopia, you can see distant objects more clearly than close ones, but depending on you age, all objects might be blurry without glasses. Hyperopia occurs when the eyeball is too short for the light rays to focus clearly on the retina.
What is astigmatism?
If you have astigmatism, your cornea is not perfectly round; rather it is more oval, and so it is not able to focus light as clearly as a round cornea. Astigmatism rarely occurs alone; it usually accompanies myopia or hyperopia.
What is presbyopia?
If you have presbyopia, you have the lost the ability to focus up close as a result of too many birthdays. 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 they have to hold the newspaper farther away from their eyes to see it clearly.