Which of the following is a common cause of visual impairment?

Deformities in the eye are a recognized cause of visual impairment because they can directly affect how light is refracted and processed by the eye. Conditions such as cataracts, glaucoma, or congenital deformities can lead to significant vision issues, impacting an individual's ability to see clearly or even at all. These structural abnormalities can impair the eye's function and, subsequently, the individual's visual perception.

Other options do not have the same direct correlation with causing visual impairment. Excessive screen time is often linked to eye strain or discomfort, but it does not typically lead to permanent visual impairment. Lack of physical exercise and high levels of sugar in the diet may have general health implications but are not established direct causes of visual impairment. Understanding the mechanics of eye health helps clarify why structural deformities carry a stronger link to visual challenges.