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

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 surgery.

Source: http://www.mayoclinic.com

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 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 early school years through the teens. A child with nearsightedness may:

• Persistently squint
• Need to sit closer to the television, movie screen or the front of the classroom
• Seem to be unaware of distant objects
• Blink excessively
• Rub his or her eyes frequently

When to see a doctor

If your difficulty clearly seeing things that are far away is pronounced enough that you can't perform a task as well as you wish, or if the quality of your vision detracts from your enjoyment of activities, see an eye doctor. He or she can determine the degree of your nearsightedness and advise you of your options to correct your vision.

Seek emergency medical care if you experience a sudden onset of flashes of floaters or a shadow covering part of your field of vision. These are warnings signs of retinal detachment, which is a rare complication of myopia. Retinal detachment is a medical emergency, and time is critical.

Regular eye exams

Since it may not always be readily apparent that you're having trouble with your vision, the American Academy of Ophthalmology recommends the following intervals for regular eye exams:

Adults

If you're at high risk of certain eye diseases, such as glaucoma, get an eye exam every two to four years up to age 40, then every one to three years between 40 and 54, and every one to two years beginning at age 55.

If you don't wear glasses or contacts, have no symptoms of eye trouble, and are at a low risk of developing eye diseases, such as glaucoma, get an eye exam at the following intervals.

• An initial exam at 40
• Every two to four years between ages 40 and 54
• Every one to three years between ages 55 and 64
• Every one to two years beginning at age 65

If you wear glasses or contacts, you'll likely need to have your eyes checked regularly. Ask your eye doctor how frequently you need to schedule your appointments. But, if you notice any problems with your vision, schedule an appointment with your eye doctor as soon as possible, even if you've recently had an eye exam. Blurred vision, for example, may suggest you need a prescription change, or it could be a sign of another problem.

Children and adolescents

Children need to be screened for eye disease and have their vision tested by a pediatrician, an ophthalmologist or another trained screener at the following ages and intervals.

• During the newborn period
• At well-child visits until school age
• During school years, every one to two years at well-child visits, or through school or public screenings

Source: http://www.mayoclinic.com

Nearsightedness usually occurs when your eye is too long or has a cornea that's curved too steeply. This causes the light rays entering each eye to focus in front of the retina, instead of on the retina, leading to blurry images. The exact reason for some people developing longer eyes is unknown, but it may be related to genetics or environmental conditions.

Normal vision

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

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.

A refractive error

However, if your cornea or lens isn't evenly and smoothly curved, light rays aren't refracted properly, and you have a refractive error. Nearsightedness is one type of refractive error. Instead of being focused precisely on your retina, light is focused in front of your retina, resulting in a blurry appearance of distant objects.

Other refractive errors

In addition to nearsightedness, other refractive errors include:

• Farsightedness (hyperopia). This occurs when your cornea is curved too little or your eye is shorter from front to back than normal. The effect is the opposite of nearsightedness. In adults, both near and distant objects are blurred.
• Astigmatism. This occurs when your cornea or lens is curved more steeply in one direction than in another. Uncorrected astigmatism blurs your vision.

Source: http://www.mayoclinic.com

Nearsightedness is diagnosed by an eye exam. A complete eye exam involves a series of tests. Your eye doctor may use various instruments, aim bright lights directly at your eyes and ask you to look through several lenses. Your doctor uses these tests to examine different aspects of your eyes and vision and to determine the prescription needed to provide clear vision with eyeglasses or contact lenses.

Source: http://www.mayoclinic.com

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. Uncorrected nearsightedness may cause you to squint or strain your eyes to maintain focus. This can lead to 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.
• Other eye problems. Severe nearsightedness puts you at a slightly increased risk of retinal detachment, glaucoma and cataracts.

Source: http://www.mayoclinic.com

You can't prevent nearsightedness. Some studies suggest you may be able to slow its progression. You can help protect your eyes and your vision by following these tips:

• Have your eyes checked. Do this regularly even if you see well.
• Control chronic health conditions. Certain conditions, such as diabetes and high blood pressure, can affect your vision if you don't receive proper treatment.
• Protect your eyes from the sun. Wear sunglasses that block ultraviolet (UV) radiation.
• Prevent eye injuries. Wear protective eyewear when doing certain things, such as playing sports, mowing the lawn, painting or using other products with toxic fumes.
• Eat healthy foods. Try to eat plenty of fruits, leafy greens and other vegetables. And studies show that your eyes benefit if you also include in your diet fish high in omega-3 fatty acids, such as tuna and salmon.
• Don't smoke. Just as smoking isn't good for the rest of your body, smoking can adversely affect your eye health as well.
• Use the right corrective lenses. The right lenses optimize your vision. Having regular exams will ensure that your prescription is correct.
• Reduce eyestrain. Look away from your computer or near-task work, including reading, every few minutes.
• Recognize symptoms. You may have a serious medical problem if you have a sudden loss of vision in one eye, experience sudden hazy or blurred vision, or see flashes of light, black spots, or halos around lights. These may indicate certain conditions, such as glaucoma, stroke, or a retinal tear or detachment. See your doctor immediately if you experience any of these symptoms.

Source: http://www.mayoclinic.com

Certain risk factors may 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 the condition is increased. The risk is even higher if both parents are nearsighted.
• Reading. People who do a lot of reading may be at increased risk of myopia.
• Environmental conditions. Some studies support the idea that a lack of time spent outdoors may increase the chances of developing myopia.

Source: http://www.mayoclinic.com