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 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
- Hold books very close while reading
- 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.
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:
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 finally every one to two years at age 55 and older.
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, it's recommended that you have an eye exam at the following intervals.
- An initial exam at 40
- Between ages 40 and 54 — every two to four years
- Between ages 55 and 64 — every one to three years
- Age 65 and older — every one to two years
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
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 images.
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. Nearsightedness can occur when your cornea is curved too much or, more commonly, when your eye is longer than normal. 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. When the eye is in a relaxed state, light will be focused beyond the back of your eye, making objects blurry. With a little effort, the eye can focus on distant objects making them clear. With greater effort, the eye can focus on near objects to allow them to be seen clearly. Problems with blurring occur when the crystalline lens begins to age and it loses its flexibility and focusing ability. You're usually able to see faraway objects clearly.
- Astigmatism. This occurs when your cornea is curved more steeply in one direction than in another. Uncorrected astigmatism blurs your vision. Typically, the images you see will be blurred more in one direction than another. For example, horizontal images may be more out of focus than are vertical or diagonal 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.
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 retinal 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 surgically reattached, this condition can cause permanent loss of vision in the affected eye.
Although a number of scientific attempts have been made to halt or slow the progression of nearsightedness, there are no proven ways to prevent the condition from occurring or progressing.