What Causes Someone to Be Nearsighted?

Nearsightedness is also called myopia. A person who is nearsighted can see objects that are near, but objects that are more distant appear out of focus. There are different degrees of nearsightedness. The degree of nearsightedness determines how distant an object must be in order to become out of focus. An optometrist can determine how much correction is needed during an eye examination.

Physical Cause

The eye has two parts that participate in focusing the light from objects into clear visual images on the retina. These images are turned into signals that are transmitted to the brain via the optic nerve. The two parts are the cornea, which is the clear surface part of the eye, and the lens, which is the clear, oval part that changes shape in the eye. When either of these eye parts isn't smoothly shaped or curved, nearsightedness can result.

Genetic Cause

Genetic factors can be a factor in the cause of nearsightedness. People who have parents with myopia are more likely to develop nearsightedness. Just as genetics affects the shape of bodies, it affects the shape of the eye.

Birth Factors

The Johns Hopkins University School of Hygiene and Public Health cites evidence that suggests that babies born prematurely or with a low birth weight have a higher risk of developing nearsightedness later in life.

Close-up Visual Work

According to the American Optometric Association, people who use their eyes for close-up work such as reading, viewing a computer monitor or other close-up visual work may have an increased risk of developing nearsightedness.

Nearsightedness Symptoms

Nearsightedness symptoms can occur with properly shaped lenses and corneas. These nearsightedness symptoms can result from changes in blood sugar levels in people with diabetes or in people who are developing cataracts.

Chlorthalidone

The Indian Journal of Ophthalmology reports a case of myopia developing in a person who took the drug chlorthalidone, which is used to treat hypertension.