Refractive errors
Refractive Errors
Refractive errors (/rɪˈfræktɪv ˈɛrərz/) are a type of vision problem that makes it hard to see clearly. They happen when the shape of your eye doesn't bend light correctly, resulting in a blurred image. The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia.
Etymology
The term "refractive error" comes from the Latin word "refractum" which means "to break up", and the English word "error". This refers to the eye's inability to properly focus light on the retina.
Types of Refractive Errors
- Myopia (/maɪˈoʊpiə/), or nearsightedness, is a condition where objects up close appear clearly, while objects far away appear blurry. This occurs when the eye grows too long or the cornea is too curved.
- Hyperopia (/ˌhaɪpəˈroʊpiə/), or farsightedness, is a condition where distant objects may be seen more clearly than objects that are near. This happens when the eye is too short or the cornea is too flat.
- Astigmatism (/əˈstɪɡmətɪzəm/) is a condition that causes blurred vision due to the irregular shape of the cornea or the lens inside the eye.
- Presbyopia (/ˌprɛzbiˈoʊpiə/) is an age-related condition in which the ability to focus up close becomes more difficult. This happens as the lens of the eye loses its flexibility.
Diagnosis and Treatment
Refractive errors are diagnosed by an optometrist or ophthalmologist during a comprehensive eye examination. Treatment options for refractive errors include eyeglasses, contact lenses, and refractive surgery.
Related Terms
External links
- Medical encyclopedia article on Refractive errors
- Wikipedia's article - Refractive errors
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