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Five frequently asked Questions

about Refractive Error

Refractive error is the most common cause of vision impairment, and uncorrected refractive error is the second leading cause of blindness in the world. 

Below are five frequently asked questions about refractive error.
 
COVER PHOTO: Hugh Rutherford (2012)


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Click on the link below to go directly to the question you want answered:

  1. What is refractive error?
  2. What are the types of refractive errors?
  3. Can refractive error lead to blindness?
  4. What are the symptoms of refractive error?
  5. How do you fix a refractive error?



1. What is refractive error?

In order to see clearly, the refractive components of the eye (lens and cornea) and the length of the eyeball must match. This enables light, from objects we are looking at, to be focused onto the retina at the back of the eye to form a clear image. When there is a mismatch between the refractive components of the eye and the length of the eyeball – the result is an out of focus or blurred image. This is known as refractive error.



2. What are the types of refractive errors?

These are the four most common types of refractive errors: 

 

Myopia (near-sightedness or short-sightedness)

Myopia is also known as near-sightedness or short-sightedness. A person with myopia will be able to clearly see objects that are near but objects far away will appear blurry.

In eyes with myopia, the image of distant objects is formed in front of the retina, usually due to the eyeball being too long. Myopia typically appears during childhood and progresses or worsens during puberty.

 

Hyperopia/ hypermetropia (farsightedness or long-sightedness)

Hyperopia – sometimes called hypermetropia – is farsightedness or long-sightedness. It occurs when the distance between the cornea and the retina is too short. This causes the light rays to focus behind the retina, rather than on it. Children with low or moderate hyperopia may experience eye strain or headaches but still have clear vision.

 

Presbyopia (loss of near vision with age)

Presbyopia is loss of near vision with age. With age, the eye’s lenses become rigid, allowing less close-range focusing flexibility. Signs of presbyopia start to emerge from around 35-45 years of age. This is a normal part of the aging process and can easily be addressed by an eye examination and a pair of glasses.

 

Astigmatism (uneven focus)

Astigmatism refers to uneven focus. Astigmatism is caused by an irregularly shaped cornea or sometimes the lens in the eye. Instead of being symmetrically curved like a soccer ball, the curves are more like that of a rugby ball. This causes the light coming through the cornea to focus unequally on the retina, resulting in a distorted or ‘stretched out’ image. In most cases, a person with astigmatism will have blurred vision, whether it’s near or far.
 
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Photographer: Hugh Rutherford (2012)
 


3. Can refractive error lead to blindness?

Uncorrected refractive error is the second leading cause of blindness in the world. Refractive error can be diagnosed by an eye care professional after a comprehensive eye examination. It can be treated in most cases with a simple pair of glasses. However, if left untreated it can have a big impact on educational outcomes, productivity, and the quality of life of those affected. In children, uncorrected refractive error can sometimes lead to amblyopia, also known as lazy eye.
 



4. What are the symptoms of refractive error?

Some of the symptoms of uncorrected refractive error are blurred or distorted vision; headaches, squinting and eye strain; difficulty reading; double vision; ‘halos’ around bright lights; haziness.



5. How do you fix a refractive error?

There are a few simple solutions that are available to correct refractive error, including eyeglasses, contact lenses, or different kinds of surgery. Eyeglasses are the most common and simple solution. An eye care professional can measure you for a pair of eyeglasses for effective correction. 

Contact lenses are a less common, but still popular treatment for correcting refractive error. They work by placing an artificial lens on the film of tears covering the eye’s surface.

Corrective surgery is a possibility for some patients. Corrective surgery options include refractive laser surgery and intraocular lens (IOL) implant surgery. 
 
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Photographer: Sophavid Choum (2013)

 

Learn more:

Find our more about uncorrected refractive errors.


DISCLAIMER: 

The content on this page is not intended to be medical advice. For specific medical advice, please contact your health professional.