Myopia

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 4, 2016
Start › Diseases › Myopia

Myopia or nearsightedness is a visual condition that causes the person afflicted to have trouble seeing things that are far away. It affects roughly a third of the United States population. While nobody knows exactly what causes it, it's easily treated and typically does not have negative effects on quality of life.

Contents

Definition & Facts

Currently, myopia affects roughly 30 percent of the United States population, and it's on the rise. The National Eye Institute found in 2010 that between the time periods of 1971-1972 and 1999-2004, the prevalence of myopia diagnoses in the United States population rose approximately 66 percent. Additional research is needed to determine why there's been such a dramatic increase. The prevalence of myopia varies by age group, but it's estimated that 24 percent of older adults (40 and up) suffer from it.

Symptoms & Complaints

Like many medical issues, the onset of myopia is gradual. This can make it difficult to recognize. Many of its symptoms involve problems with visual acuity, but some do not. Symptoms include:

  • Blurry vision- Those who have myopia will likely experience blurry vision when they stare at objects in the distance. Objects that are close will generally be clearer.
  • Squinting
  • Frequent headaches - The strain that myopia places on the eyes as they struggle to see can cause persistent headaches
  • General trouble with seeing

Symptoms among children include:

  • Eye rubbing - Many children with myopia will frequently rub their eyes.
  • Sitting closer to the TV/teacher - A child with myopia will usually simply move closer to things in order to see them.
  • Very frequent blinking - Just like eye rubbing, blinking frequently is a sign of myopia in children.
  • Unawareness of distant objects

Causes

While the exact causes of myopia still need to be uncovered by research, some evidence suggests that hereditary causes are at least partially responsible for the development of myopia. Some suggest that the eye strain caused by frequent reading can cause myopia to develop, but this has not been proven. Some research suggests that contact lenses and glasses can cause nearsightedness to develop further.

A myopic eye is more oblong than an eye that sees normally. The abnormal shape of the eye causes light entering the eye to not be refracted correctly, making it difficult to see clearly. When a lens - either as part of glasses or contacts - is placed over the eye, it correctly refracts light, thus allowing the affected person to see clearly.

Diagnosis & Tests

The best way to detect myopia early on is to have regular eye examinations. During an eye exam, an ophthalmologist, or eye doctor, will start with a vision test. In this test, one will be asked to read letters from afar. Sometimes, young children are shown a video on a small TV and asked to describe what happens.

If the vision tests show that the patient is having trouble seeing, the ophthalmologist will then shine a light in the eye. The way the light reflects off the retina will show the doctor if the patient is nearsighted or farsighted (hyperopia). Because treatment involves corrective lenses, the doctor will use a phoropter to measure the exact refractive error in each eye. Then, lenses - either contacts, glasses, or both - will be specially made for the patient to help correct eyesight and bring the corrected vision as close to 20/20 as possible.

Treatment & Therapy

While it can be difficult or impossible to fully correct myopia, there are many treatments available. The earliest treatment developed is that of glasses. Now, though, one has the option of contact lenses, and most recently, laser eye surgery has been developed. While corrective lenses refract light to make it easier to see, corrective surgery permanently alters the eye so one can see clearly without needing lenses over the eyes.

If one is not sure what treatment is best, the person should talk to the ophthalmologist. He or she can discuss pros, cons, and costs of each. In addition, some eye conditions may not be correctable with certain options (for instance, if a person has extreme astigmatism, some contacts may not work).

Prevention & Prophylaxis

It's impossible to definitively prevent myopia from developing, but early diagnosis can help an individual avoid discomfort and inconvenience. While many people develop myopia early in life, there are still plenty of people who develop it later.

If one is not at risk for glaucoma or other serious issues, and one has reached age 40 with no need for glasses, then it's wise to have an initial exam at 40, and then one every two to four years between 40 and 54. An exam every one to three years is recommended between 55 and 64, and then an exam every one to two years after age 65.

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