What is Refractive Errors?
Refractive errors are errors in which the eye’s ability to focus light is affected, causing reduced visual capacity. This is the most common and well-known eye condition including various types such as spherical errors and cylindrical errors.
Refractive errors affect a large part of the population. To some degree almost everyone possesses reflective errors in one eye (asymptomatic) or in both eyes (symptomatic).
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Spherical errors occur when the optical power of the eye is either too large or too small to focus light correctly on the retina, the light-sensitive tissue lining the inner surface of the eye. Examples of spherical errors are:
- Myopia: myopia is often referred to as nearsightedness. This causes the image that one sees when looking at a distant object to be out of focus, but an image that one sees up close to be in focus.
- Hyperopia: hyperopia is often referred to as farsightedness. This causes the image that one sees when looking at a close object to be out of focus, but an image that one sees in the distance to be in focus.
Normal vision vs. Myopia
Cylindrical errors occur when the optical power of the eye is too powerful or too weak. Examples of cylindrical errors are:
- Astigmatism: astigmatism is caused by an irregularly shaped cornea (the transparent part of the eye that covers the iris, pupil and anterior chamber). In an eye with astigmatism, light fails to come to a single focus point to produce clear vision. Instead, multiple focus points occur.
- Presbyopia: presbyopia causes the flexibility of the lens to decline, resulting in difficulty with focussing on nearby objects.
What are the symptoms of Refractive errors
Symptoms of refractive errors vary per individual and may
- eye strain
- blurred or distorted images either up close or in the distance
What to expect from Refractive Errors
How refractive errors are treated depends on the amount and the severity of the condition. Glasses and contact lenses are often used to correct the blurred vision resulting from a refractive error. In some cases, refractive surgery may be an option to correct the underlying cause. Discuss the best options for your specific case with your eye care professional.
More information about Refractive Errors
There is extensive information available about refractive errors. The information included is intended to inform you about the basics of this eye condition, and is not intended as a replacement for information from your physician or eye specialist. Information regarding assistive devices that can help you if you have been diagnosed with refractive errors is included. Our recommendations can be found under Tools and Resources.