näkövirheitä
Näkövirheitä, or refractive errors, are common conditions that affect the way the eye focuses light, leading to blurry or distorted vision. These occur when the eye's shape or the length of the eyeball prevents light from being focused precisely on the retina, the light-sensitive tissue at the back of the eye. The most frequent types of näkövirheitä are myopia (likinäköisyys), hyperopia (kaukotaittoisuus), and astigmatism (hajataittoisuus). Myopia causes distant objects to appear blurry, while hyperopia makes near objects difficult to see clearly. Astigmatism results from an irregularly shaped cornea or lens, causing blurred vision at all distances. Presbyopia (ikänäköisyys), a natural aging process, is also considered a type of refractive error, characterized by difficulty focusing on close-up objects that typically begins around age 40.
The causes of näkövirheitä are often genetic, though environmental factors can also play a role. Diagnosis