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:
- eyes that hurt or feel tired
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
- 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)
Correction for Nearsightedness:
Your eye doctor can diagnose nearsightedness by performing a complete eye exam.
Correction for nearsightedness may include:
- corrective lenses
- corneal refractive therapy
- refractive surgery
Eyeglasses and contact lenses are examples of corrective lenses. These devices compensate for the curvature of your cornea or the elongation of your eye by shifting the focus of light as it enters your eye.
Your prescription strength will depend on how far you can see clearly. You may need to wear corrective lenses all the time or just for certain activities, such as driving.
Contact lenses generally give you a wider field of corrected vision than glasses. Contact lenses are applied directly to the corneas of your eyes. Some patients cannot tolerate contact lenses because they irritate the surface of their eyes.
Refractive surgery is a permanent form of correction for nearsightedness. Also called laser eye surgery, the procedure reshapes your cornea to focus light onto the retina. Most people who have refractive eye surgery no longer need to wear contact lenses or eyeglasses.
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 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