Illinois Vision Certification Practice Test

What kind of lens is used to correct astigmatism?

1. Convex lens

2. Concave lens

3. Cylindrical lens

4. Bifocal lens

The correct answer is: Cylindrical lens

Cylindrical lenses are specifically designed to correct astigmatism, which is a refractive error caused by the irregular shape of the cornea or lens in the eye. In astigmatism, light rays entering the eye do not focus evenly on the retina, leading to blurred or distorted vision. Cylindrical lenses have different optical power in different meridians, effectively compensating for the unequal curvature of the eye. This characteristic allows them to focus light more accurately and provide clearer vision in individuals with astigmatism. In contrast, convex lenses are primarily used to correct hyperopia (farsightedness), while concave lenses are used for myopia (nearsightedness). Bifocal lenses are a combination of two types of lenses typically used to assist with both distance and near vision, but they are not specifically designed for astigmatism. Thus, cylindrical lenses are the most appropriate choice for correcting this specific refractive error.