Astigmatism is a common eye condition that affects millions of people worldwide. It is a type of refractive error that occurs when the cornea or lens of the eye has an irregular shape. This irregular shape causes light to be focused unevenly on the retina, resulting in blurred or distorted vision. In this article, we will explore the definition and meaning of astigmatism, its origin, associations, synonyms, antonyms, and root words.
Definitions
Astigmatism is a type of refractive error that causes blurred or distorted vision. It occurs when the cornea or lens of the eye has an irregular shape, which causes light to be focused unevenly on the retina. This can result in difficulty seeing fine details, such as letters on a page or road signs.
Origin
The word astigmatism comes from the Greek words “a” meaning “without” and “stigma” meaning “point.” It was first used in the mid-19th century to describe the irregular shape of the cornea or lens that causes blurred vision.
Meaning in different dictionaries
According to the Merriam-Webster Dictionary, astigmatism is defined as “a defect of an optical system (such as a lens) causing rays from a point to fail to meet in a focal point resulting in a blurred and imperfect image.”
The Oxford English Dictionary defines astigmatism as “a defect in the eye or lens causing a distorted image, resulting from the eye or lens not being spherical.”
Associations
Astigmatism is often associated with other eye conditions such as myopia (nearsightedness) and hyperopia (farsightedness). It can also be caused by certain medical conditions such as keratoconus, a condition in which the cornea becomes thin and cone-shaped.
Synonyms
Some synonyms of astigmatism include:
- Refractive error.
- Irregular cornea.
- Corneal astigmatism.
- Lenticular astigmatism.
- Cylinder error.
Antonyms
There are no direct antonyms of astigmatism, but clear vision could be considered an opposite condition.
The same root words
There are no other words with the same root as astigmatism.
Example Sentences
- John’s astigmatism caused him to have difficulty reading small print.
- Mary’s optometrist prescribed glasses to correct her astigmatism.
- The irregular shape of his cornea caused his astigmatism.
- The contact lenses corrected her astigmatism and improved her vision.