Illinois Vision Certification Practice Test

Astigmatism is primarily an issue with which part of the eye?

1. Retina

2. Lens

3. Cornea

4. Iris

The correct answer is: Cornea

Astigmatism is primarily associated with an irregular curvature of the cornea or sometimes the lens of the eye. When the cornea is not perfectly spherical, it causes light to focus on multiple points in the eye instead of a single point, leading to blurred or distorted vision. This condition occurs because the cornea's shape affects the eye's ability to refract light properly, thus creating a variation in visual acuity. While the other structures listed are essential to the overall function of the eye, the cornea's shape is the key aspect in the development of astigmatism. In contrast, the retina is responsible for capturing light and sending visual signals to the brain, the lens helps focus light onto the retina, and the iris controls the amount of light entering the eye—all of which do not directly cause the refractive error seen in astigmatism.