Nearsightedness usually results when the eye is too long or oval-shaped rather than round. It also may result when the curve of the cornea is too steep. With these changes, light rays come to a point in front of the retina and cross. The messages sent from the retina to the brain are perceived as blurry.

Adults with nearsightedness may notice difficulty reading street signs or signs in stores. Some people may experience blurry vision in dim light, as with nighttime driving, even if they see clearly in daylight. This condition is called night myopia.

If you have diabetes, a family history of eye disease, high blood pressure, or other risks of heart or vascular disease, you'll likely need more-regular eye exams. Also, you'll likely need more-regular exams if you already have prescription glasses or contacts or if you've had surgery for vision correction. Your healthcare professional or eye care specialist can recommend how often to get an exam.

These are warnings signs of the retina becoming detached from the back of the eye. This condition is a medical emergency requiring prompt treatment. Significant nearsightedness is associated with an increased risk of retinal detachment.

Time-lapse videos are automatically created by speeding up a video so that it fits into a length between 15 and 30 seconds. For example, if you take a 100-second time-lapse, it'll be sped up 4x and the final video will be 25 seconds long. There's no limitation on how long you may take a time-lapse video, but for best results, make sure your Chromebook is plugged into a power source.

The American Academy of Ophthalmology recommends that healthy adults with no known problems with vision or eye disease should get a complete eye exam on the following schedule:

With typical vision, an image is sharply focused onto the retina. In nearsightedness, the point of focus is in front of the retina, making distant objects appear blurry.

For you to see, light has to pass through the cornea and lens. These parts of the eye bend — also called refract — the light so that the light is focused directly on the retina at the back of your eye. These tissues translate light into signals sent to the brain, which lets you perceive images.

Nearsightedness is a common vision condition in which close objects look clear but far objects look blurry. The medical term for nearsightedness is myopia. Myopia happens when the shape of the eye — or the shape of certain parts of the eye — causes light rays to bend or refract. Light rays that should be focused on nerve tissues at the back of the eye, called the retina, are focused in front of the retina instead.

Your child's pediatrician or other healthcare professional does relatively simple exams to check the health of your child's eyes at birth, between 6 and 12 months of age, and between 12 and 36 months of age. If there are any problems, you may be referred to a doctor specializing in eye health and care, called an ophthalmologist.

Make an appointment for yourself if you notice a change in your vision, have difficulty performing tasks such as driving or find that the quality of your vision affects your enjoyment of activities.

School-age children may have difficulty seeing things on whiteboards or screen projections in the classroom. Younger children might not express difficulty seeing, but they may have the following behaviors that suggest difficulty seeing:

Nearsightedness usually develops during childhood and adolescence. Typically, it becomes more stable between the ages of 20 and 40. It tends to run in families.

Nearsightedness is a refractive error. This problem happens when the shape or condition of the cornea — or the shape of the eye itself — causes an inaccurate focusing of the light passing into the eye.

A basic eye exam can confirm nearsightedness. You can correct the blurry vision with eyeglasses, contact lenses or refractive surgery.

Vision screenings are tests to check for vision problems. A screening test may be done by a pediatrician, an ophthalmologist, an optometrist or another trained provider. Vision screenings are often offered at schools or community centers.

Both children and adults may not be aware of problems with vision or changes that happen gradually. The American Academy of Ophthalmology recommends regular vision screenings to ensure timely diagnosis and treatment.

If a problem is found in a screening test, you'll likely need to schedule a complete eye exam with an optometrist or ophthalmologist.

With typical vision, an image is sharply focused onto the retina. In nearsightedness, the point of focus is in front of the retina, making distant objects appear blurry.

Make an appointment with an eye care specialist if your child shows any signs of vision problems or if a teacher reports possible problems.