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Understanding Refractive Errors

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Everything You Need to Know About Refraction & Refractive Errors

The term refraction refers to the bending of light as it passes through one object to another.

Our eyes work by refracting light as it passes through the cornea and the lens. From here, the light is then focused on the retina which converts the light rays into messages to be interpreted by the brain.

These messages are sent from the retina to the brain via the optic nerve. The brain then processes these messages into the images we see.

What is a Refractive Error?

By applying our knowledge of what refraction is, we can assume that a refractive error is a result of light being bent incorrectly.

A refractive error occurs when the shape of the eye prevents the light from focusing on the retina. This can be caused by either the length of the eyeball, a misshaped cornea, or with age.

Who Can They Affect?

Refractive errors can affect both children and adults, regardless of age. Those whose parents have a refractive error are more likely to get one.

All adults over 35 are at risk of developing presbyopia, a very common refractive error that occurs with age.

Types of Refractive Errors?


Commonly known as farsightedness, hyperopia is a common type of refractive error that makes distant objects appear clear while nearby objects are not. Severe hyperopia could result in blurred vision regardless of the distance of the object.

  • Symptoms of hyperopia include blurred vision up close, squinting to see close objects, and headaches after reading up-close material.


Opposite to hyperopia, myopia is a condition that makes far away objects blurry while nearby ones are clear. This is due to light being focused in front of the retina opposed to directly on it.

  • Symptoms of myopia are similar to hyperopia, however, are experienced from opposite tasks. For example, a person with myopia may experience headaches when attempting to read road signs while driving.


Much like myopia and hyperopia, astigmatism results in your vision being blurry. This is due to the fact that light is not being evenly focused on the retina.

  • Symptoms of astigmatism are difficult to pinpoint as they are the same as other refractive errors such as hyperopia and myopia. However, unlike other errors, someone with astigmatism may experience blurred vision at all distances, as well as difficulty seeing at night.


Not to be confused with hyperopia, presbyopia is an age-related condition that results in the inability to focus on up-close objects.

With age, our lens cannot manipulate its shapes enough to allow us to view objects up close clearly, resulting in light not being focused on the retina properly.

Symptoms of presbyopia are similar to hyperopia. These symptoms include: eyestrain after doing close work, difficulty reading small print, the need for brighter light to read, and holding material at arm’s distance in order to read it.

Written by Dr. Daniel Evans

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