Nearsightedness

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Definition

Nearsightedness (myopia) is a common vision condition in which you can see near objects clearly, but objects farther away are blurry.

The degree of your nearsightedness affects your ability to focus on distant objects.  People with severe nearsightedness can see clearly only objects just a few inches away, while those with mild nearsightedness may clearly see objects up to several yards away.

Nearsightedness may develop gradually or rapidly, often worsening during childhood and adolescence.  Nearsightedness tends to run in families.

A basic eye exam can confirm nearsightedness. You can easily correct the condition with eyeglasses or contact lenses. Another treatment option for nearsightedness is refractive surgery.

Symptoms

Nearsightedness symptoms may include:

  • Blurry vision when looking at distant objects
  • The need to squint or partially close the eyelids to see clearly
  • Headaches caused by excessive eyestrain
  • Difficulty seeing while driving a vehicle, especially at night (night myopia)

Nearsightedness is often first detected during childhood and is commonly diagnosed between the ages of 5-18.  A child with nearsightedness may:

  • Persistently squint
  • Need to sit closer to the television, movie screen or the front of the classroom
  • Hold books very close while reading
  • Seem to be unaware of distant objects
  • Blink excessively
  • Rub their eyes frequently

Causes

To focus the images it sees, your eye relies on two critical parts:

  • The cornea, the clear front surface of your eye
  • The crystalline lens, a clear structure inside your eye that changes shape to help focus objects up close

In a normally shaped eye, each of these focusing elements has a perfectly smooth curvature like the surface of a smooth rubber ball.  A cornea and lens with such curvature bend (refract) all incoming light in such a way as to make a sharply focused image on the retina at the back of your eye.  If you’re nearsighted, the light rays that enter each eye are focused in front of the retina, instead of on the retina.  This causes blurry distance images.

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

  • Family history- nearsightedness tends to run in families.  If one of your parents is nearsighted, your risk of developing nearsightedness is increased.  The risk is even higher if both parents are nearsighted.
  • Close work- there may be an increased incidence of nearsightedness among people who do a lot of reading or other close work.

Complications

Nearsightedness may be associated with several complications, such as:

Reduced quality of life:  Uncorrected nearsightedness can affect your quality of life. You might not be able to perform a task as well as you wish, and your limited vision may detract from your enjoyment of day-to-day activities.

Eyestrain:  Squinting to see in the distance can cause eyestrain and headaches.

Impaired safety:  Your own safety and that 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.

Glaucoma:  Severe nearsightedness increases your risk of developing glaucoma, a potentially serious eye disease.

Retinal tear and detachment:  If you’re significantly nearsighted, it’s possible that the retina of your eye is thin.  The thinner your retina, the higher your risk of developing a retinal hole, tear or detachment. If you experience a sudden onset of flashes, floaters, or a dark curtain or shadow across part of your eye, seek medical assistance immediately. Retinal detachment is a medical emergency, and time is critical. Unless the detached retina is promptly reattached surgically, this condition can cause permanent loss of vision in the affected eye.

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