Definition:
Myopia is the medical term for nearsightedness. People with myopia
see objects more clearly when they are close to the eye, while distant objects
appear blurred or fuzzy. Reading and close-up work may be clear, but distance
vision is blurry.
Causes,
incidence, and risk factors: People are able to see because
the front part of the eye bends (refracts) light and points it to the back
surface of the eye, called the retina.
Nearsightedness occurs when the
physical length of the eye is greater than the optical length.
This makes it more difficult for the
eyes to focus light directly on the retina. If the light rays are not clearly
focused on the retina, the images you see may be blurry.
Nearsightedness affects males and females equally. People who have a family
history of nearsightedness are more likely to develop it. Most eyes with
nearsightedness are healthy, but a small number of people with severe myopia
develop a form of retinal degeneration.
Symptoms
of Nearsightedness: The most obvious symptom of nearsightedness is
blurry vision when looking at faraway objects. Children may have trouble seeing
the blackboard at school. Adults might not be able to see street signs clearly while driving. Other signs of
nearsightedness include:
- headaches
- eyes that hurt or
feel tired
- squinting
The symptoms
of nearsightedness usually go away after treatment with eyeglasses or contact lenses. Headaches and eye fatigue may linger
for a week or two as you adjust to your new eyeglass or contact lens
prescription.
Signs
and tests:
A nearsighted person can easily read the Jaeger eye
chart (the chart for near reading), but has trouble reading the Snellen eye
chart (the chart for distance).
A general eye examination,
or standard
ophthalmic exam may include:
- Eye
pressure measurement (See: Tonometry)
- Refraction
test, to determine the correct prescription for glasses
- Retinal
examination
- Slit-lamp
exam of the structures at the front of the eyes
- Test of
color vision, to look for possible color blindness
- Tests
of the muscles that move the eyes
- Visual acuity, both at a distance (Snellen), and close up (Jaeger)
Expectations
(prognosis): Early diagnosis
of nearsightedness is important, because a child can suffer socially and
educationally by not being able to see well at a distance.
Complications:
- Complications can
occur in people who use contact lenses (corneal
ulcers and infections)
- Complications of
laser vision correction are uncommon, but can be serious
- People with myopia
can, in rare cases, develop retinal
detachments or retinal degeneration
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