Myopia is a refractive error that makes distant objects appear blurry. It happens when the shape of the eye focuses light in front of the retina (a light-sensitive layer of tissue in the back of your eye), instead of onto it.

If you are nearsighted, your eye doctor may prescribe glasses or contact lenses to help you see clearly.

The most common symptoms of myopia are:

• Difficulty seeing things that are far away
• You have to close your eyes to see clearly
• Eye strain (if your eyes feel tired or painful)

Some people who are nearsighted get a headache, but this is less common.

If you have mild myopia, you may not notice any symptoms. That's why it's important to get regular eye exams so your doctor can make sure you see as clearly as possible.

People with severe myopia (also called high myopia) may also be at higher risk for other eye conditions, such as retinal detachment (when the retina is pulled out of its normal position).

Anyone can be nearsighted, but you are at higher risk if you have family members who are also nearsighted.

Myopia usually starts between the ages of 6 and 14 and gets worse until your early 20s. Children who spend more time outdoors are less likely to be myopic, but experts aren't sure why.

Myopia occurs when your eyeball grows too long from front to back, or when there are problems with the shape of your cornea (clear front layer of the eye) or lens (an inner part of the eye that helps eye focus).

These problems cause the light to focus in front of the retina instead of on it - and that makes distant objects blurry.

Ophthalmologists can check for nearsightedness as part of a comprehensive eye exam. The exam is simple and painless.