Overview

Nearsightedness (myopia) is a common vision condition in which near objects appear clear, but objects farther away look blurry. It occurs when the shape of the eye — or the shape of certain parts of the eye — causes light rays to bend (refract) inaccurately. Light rays that should be focused on nerve tissues at the back of the eye (retina) are focused in front of the retina.

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

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

Symptoms

Nearsightedness signs or symptoms may include:

  • Blurry vision when looking at distant objects
  • The need to squint or partially close the eyelids to see clearly
  • Headaches
  • Eyestrain

Children may have difficulty seeing things on white boards or screen projections in the classroom. Younger children might not express difficulty seeing, but they may have the following behaviors that suggest difficulty seeing:

  • Persistently squint
  • Seem unaware of distant objects
  • Blink excessively
  • Rub their eyes frequently
  • Sit close to the television

Adults with myopia may notice difficulty reading street signs or signs in a store. 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.

When to see a doctor

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

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

Seek emergency medical care if you experience any of the following:

  • Sudden appearance of many floaters — tiny specks or lines that seem to drift through your field of vision
  • Flashes of light in one or both eyes
  • A curtain-like gray shadow covering all or part of your field of vision
  • A shadow in your outer or side vision (peripheral vision)

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.

Regular eye exams

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 a timely diagnosis and treatment.

Children and adolescents

Your child's pediatrician or other health care provider will conduct 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 medical doctor specializing in eye health and care (ophthalmologist).

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

The recommended times for screening are as follows:

  • At least once between ages 3 and 5
  • Before kindergarten, usually age 5 or 6
  • Annually through the end of high school

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

Adults

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:

  • At least once between ages 20 and 29
  • At least twice between ages 30 and 39
  • Every 2 to 4 years from ages 40 to 54
  • Every 1 to 3 years from ages 55 to 64
  • Every 1 to 2 years after age 65

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 health care provider or eye care specialist will recommend how often to get an exam.

Causes

Your eye has two parts that focus images:

  • The cornea is the clear, dome-shaped front surface of your eye.
  • The lens is a clear structure about the size and shape of an M&M's candy.

In order for you to see, light has to pass through the cornea and lens. They bend (refract) the light, so that the light is focused directly on the nerve tissues (retina) at the back of your eye. These tissues translate light into signals sent to the brain, which enables you to perceive images.

Refractive errors

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

Nearsightedness usually results from the eye being too long or oval-shaped rather than round. It may also result from the curve of the cornea being too steep. These changes result in light rays coming to a point in front of the retina and crossing. The messages sent from the retina to the brain are perceived as blurry.

Other refractive errors include:

  • Farsightedness (hyperopia). This occurs when your eyeball is shorter than a typical eye or your cornea is curved too little. Some people may perceive distant objects as somewhat clear, but near objects appear blurry. For some people with farsightedness, objects are blurry at all distances.
  • Astigmatism. This occurs when your cornea or lens is curved more steeply in one direction than in another. Vision is distorted or blurry at all distances.

Risk factors

Certain risk factors may increase the likelihood of developing nearsightedness, such as the following:

  • Genetics. Nearsightedness tends to run in families. If one of your parents is nearsighted, your risk of developing the condition is increased. The risk is higher if both parents are nearsighted.
  • Prolonged close-up activities. Prolonged reading or other close-up activities are associated with an increased risk of nearsightedness.
  • Screen time. Studies have shown that children who use computers or smart devices for long periods have a greater risk of developing nearsightedness.
  • Environmental conditions. Some studies support the idea that a lack of time spent outdoors may increase the risk of nearsightedness.

Complications

Nearsightedness is associated with a variety of complications from mild to severe, such as:

  • Poor school experiences. Children with myopia or other vision problems can experience delays in reading or other academic skills, difficulty with social interactions, and poor self-esteem.
  • Reduced quality of life. Uncorrected nearsightedness can prevent you from performing daily tasks well or enjoying activities.
  • Eyestrain. Uncorrected nearsightedness may cause persistent eyestrain and headaches.
  • Impaired safety. Your safety and the safety of others may be jeopardized if you have an uncorrected vision problem. This could be especially serious if you are driving a car or operating heavy equipment.
  • Other eye problems. Severe nearsightedness puts you at an increased risk of retinal detachment, glaucoma, cataracts and other serious eye conditions.