Eye power, also known as refractive error, refers to the way your eye focuses light onto the retina at the back of the eye. A "plus" (+) sign in front of the number on your prescription indicates that you are farsighted (hyperopia), meaning your eye focuses light behind the retina. A "minus" (-) sign means you are nearsighted (myopia), meaning your eye focuses light in front of the retina. These numbers determine the lens power needed to provide clear vision for each eye, whether through eyeglasses or contact lenses.
Here's a breakdown of the common types of eye power:
- Hyperopia (Farsightedness): Individuals with hyperopia have difficulty seeing objects up close. Their eyes focus light behind the retina, requiring a convex lens (plus power) to correct vision.
- Myopia (Nearsightedness): Individuals with myopia have difficulty seeing objects far away. Their eyes focus light in front of the retina, requiring a concave lens (minus power) to correct vision.
- Astigmatism: This occurs when the cornea, the clear front part of the eye, has an irregular shape. It causes blurry vision at all distances. Astigmatism is corrected by using a cylindrical lens that focuses light evenly on the retina.
Eye power can be measured by an eye care professional during an eye exam. A comprehensive eye exam can detect refractive errors and other potential eye health problems.
