What type of lens is used to correct hyperopia?

Hyperopia, or farsightedness, is a common refractive error where distant objects may be seen more clearly than nearby objects. This condition occurs when the eyeball is shorter than normal or when the cornea has too little curvature, causing light entering the eye to focus behind the retina instead of directly on it.

To correct hyperopia, a convex lens is used. Convex lenses are shaped such that they are thicker in the middle and thinner at the edges. This shape allows them to converge light rays before they enter the eye, helping to focus the light directly onto the retina. By compensating for the insufficient curvature or shorter length of the eyeball, convex lenses enable people with hyperopia to see nearby objects more clearly.

In contrast, other types of lenses such as concave lenses diverge light and are typically used to correct myopia, where light focuses in front of the retina. Cylindrical lenses are specifically designed for astigmatism correction, addressing irregularities in the shape of the cornea or lens. Bifocal lenses combine two different optical powers to help with both distance and near vision but are not specifically designed to correct hyperopia on their own. Thus, the convex lens is the appropriate choice for correcting hyperopia.