What occurs when a cataract develops in the eye?

When a cataract develops in the eye, the lens becomes cloudy. This clouding of the lens occurs as proteins in the lens begin to clump together, affecting the clarity of the lens and impairing vision. As the cataract progresses, individuals may experience blurred vision, difficulty with night vision, and sensitivity to glare, among other symptoms. The primary issue lies in the lens, which is responsible for focusing light onto the retina, and when it becomes opaque, vision is significantly compromised.

The other choices highlight conditions or changes that are not directly related to cataracts. Pupil dilation refers to changes in the size of the pupil usually in response to light or focus, but this is not a characteristic of cataracts. Thinning of the macula is associated with age-related macular degeneration, which is a different eye condition. A grayish-white circle around the cornea may indicate a condition like a corneal arcus, not cataracts. Thus, the development of a cataract specifically leads to the lens becoming cloudy, resulting in the visual disturbances associated with this condition.