Refraktiohäiriö

Refraktiohäiriö, commonly known as refractive error, is a vision condition that affects the way light focuses on the retina, the light-sensitive tissue at the back of the eye. When light does not focus properly, images appear blurry. The most common types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia.

Myopia occurs when the eye focuses images in front of the retina, rather than on it. This results in distant objects appearing blurry, while close objects are seen clearly. Hyperopia happens when the eye focuses images behind the retina. This can cause both near and distant objects to appear blurry, although the effect is often more noticeable with distant vision. Astigmatism is caused by an irregularly shaped cornea or lens, which leads to distorted vision at all distances. Presbyopia is an age-related condition that typically affects people over 40. It occurs when the lens of the eye loses its flexibility, making it difficult to focus on close-up objects.

Refractive errors are usually diagnosed through a comprehensive eye examination. Vision tests, such as reading an eye chart, are used to assess visual acuity. Other tests may be performed to measure the refractive power of the eye.

The most common treatments for refractive errors include eyeglasses and contact lenses, which correct vision by reshaping the way light enters the eye. Refractive surgery, such as LASIK, is another option that permanently alters the shape of the cornea to improve vision.