Myopia, also known as nearsightedness, is an eye defect characterized by the inability of the eye to focus light on the retina. Myopia is characterized by the ability to see nearby objects clearly while distant objects appear blurred. It occurs when the eyeball is elongated or the cornea is too curved, causing the incoming light to focus in front of the retina instead of directly on it.

Both astigmatism and myopia (nearsightedness) are eye defects caused by the inability of the eye to focus light properly on the retina, but they manifest differently: astigmatism causes blurred or distorted vision due to an irregularly shaped cornea or lens, while myopia causes blurry vision at a distance because the eye focuses light in front of the retina.