Which refractive error causes difficulty in seeing distant objects?

Myopia, commonly known as nearsightedness, is the refractive error that causes difficulty in seeing distant objects clearly while nearby objects may be seen well. This condition occurs when the eye is either too long or has an excessively curved cornea, causing light rays entering the eye to focus in front of the retina instead of directly on its surface. As a result, objects that are farther away appear blurred.

In contrast, hyperopia (farsightedness) is characterized by trouble focusing on close-up objects, and emmetropia refers to a state where vision is normal, with no refractive error present. Astigmatism is caused by an irregular shape of the cornea or lens, leading to blurred vision at all distances. Hence, myopia specifically addresses the difficulty with distance vision, making it the correct answer to the question about which refractive error impairs the ability to see distant objects clearly.