Myopia
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.
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