What type of vision error does a concave lens typically correct?

Concave lenses are designed to correct myopia, commonly known as nearsightedness. In individuals with myopia, distant objects appear blurry while close objects can be seen clearly. This occurs because the eye is either too long or the cornea has too much curvature, causing light rays to focus in front of the retina instead of directly on it.

When a concave lens is used, it diverges light rays before they enter the eye, effectively allowing the rays to extend further back so that they converge directly on the retina. This adjustment helps improve distance vision for those suffering from myopia, enabling them to see distant objects more clearly.

The other vision errors listed, such as hyperopia (farsightedness), astigmatism (irregular shape of the cornea), and presbyopia (age-related difficulty in focusing on close objects), require different types of lenses for correction. Hyperopia is corrected with convex lenses, astigmatism may require cylindrical lenses, and presbyopia typically benefits from bifocal or multifocal lenses.