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Nearsightedness, or myopia, is a refractive error like astigmatism and farsightedness. About 20 to 30 percent of the population is nearsighted. People with myopia have difficulty seeing distance objects clearly, like highway signs, while near vision is sharper for tasks such as reading or sewing.

In the nearsighted eye, the cornea is more rounded than it needs to be, and the eye itself is usually longer than normal. This causes light to become focused in front of the retina, so that the far images look blurred, without spectacle or contact lens correction. If the cornea is not rounded or spherical, objects may also be distorted or ghosts images may appear.

 


Far objects look blurry to nearsighted people

In a nutshell, Myopia, or near-sightedness, is the ability to clearly see objects up close but not those at a distance.

The eyeball in a nearsighted person is slightly longer than usual from front to back. Light rays of images you see focus in front of the retina, the light-sensitive part of the eye, rather than directly on the retina. When this happens, you have blurry distance vision.

Nearsightedness runs in families and usually appears in childhood. Sometimes myopia plateaus, or sometimes it worsens with age, called myopic creep.

Nearsighted people often complain of:

  • headaches
  • eyestrain
  • squinting
  • fatigue when driving
  • playing sports
  • looking more than a few feet away.
If you experience these symptoms while wearing your glasses or contact lenses, you may need a comprehensive eye examination as well as a new prescription.


Myopia is a refractive error, meaning that the light rays bend incorrectly into the eye to transmit images to the brain. Changing the refraction, or the way the light rays bend, corrects nearsightedness. Refractive errors may be corrected by glasses, contact lenses, refractive surgery or orthokeratology.

How a spherical lens corrects myopia

  
The shape of a myopic eye focuses images in front of the retina, producing blurred distance vision.
 
By reducing the cornea's focusing power, a spherical contact lens creates a single focal point on the retina where vision is sharpest.

 

Depending on your refractive error, you may need to wear your glasses or contact lenses all the time, or only when you need distance vision, like driving, seeing a chalkboard or watching a movie. With myopia, your prescription is a negative number, such as -3.00. The higher the numeral, the stronger your lenses will be. Refractive surgery can reduce or even eliminate your dependence on glasses or contacts.

The most common procedures are performed with an excimer laser. In photorefractive keratectomy or PRK, the laser removes a layer of corneal tissue, which flattens the cornea and allows light rays to focus closer to or even on the retina. In laser-assisted in situ keratomileusis (LASIK), a flap is cut through the top of the cornea, a laser removes some corneal tissue, then the flap is dropped back into place. LASIK is the most common surgery used to correct myopia. An even newer procedure for correcting mild myopia is the implantation of plastic corneal rings, which also alter the shape of the cornea. One advantage of the rings is that they may be removed in case of a problem or adjusted should a prescription change become necessary. Or they can be left in place permanently.

In orthokeratology, special retainer contact lenses slowly reshape the cornea to correct myopia over time. Depending on your eyes, these contact lenses may need to be worn only at night. Orthokeratology is controversial in the eyecare community, with some practitioners reporting great results and others finding that effects don't last long enough.

For more information of Myopia and its correction:

 

Source(s): All above information & images are based on an article written by Gretchyn Bailey allaboutvision.com and from an article at alphavista.com and self created images. All rights reserved by respective owners.

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Disclaimer: Any information displayed here is just for educational purposes, and may not be taken as an expert advice and should not be applied in life without consulting your eye doctor/specialist. We here by take no responsiblity of the accuracy of the above content as they have been taken from various sources.

Did you know ?

There are today some 160 MILLION people in the world with disabling visual impairments; this figure will double in the next 25 years, unless decisive public health action is taken.

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