Eye chart
Eye chart
An Eye chart (/aɪ tʃɑːrt/) is a chart used by optometrists, ophthalmologists, and other healthcare professionals to measure visual acuity. The chart typically contains several rows of letters, numbers, or symbols, which decrease in size from top to bottom.
Etymology
The term "Eye chart" is derived from the English words "eye", referring to the organ of sight, and "chart", meaning a sheet of information in the form of a table or diagram.
History
The most commonly used eye chart is known as the Snellen chart, named after the Dutch ophthalmologist Herman Snellen who developed it in 1862. Other types of eye charts include the LogMAR chart, Landolt C, and the Lea test.
Usage
Eye charts are used in the diagnosis of various eye disorders, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. They are also used to assess the effectiveness of corrective measures like glasses or contact lenses.
Related terms
- Visual acuity: The sharpness of vision, measured by the ability to discern letters or numbers at a given distance according to a fixed standard.
- Optometrist: A healthcare professional who provides primary vision care, including comprehensive eye examinations and correction of common vision disorders.
- Ophthalmologist: A medical doctor who specializes in eye and vision care, diagnosing and treating all eye diseases, performing eye surgery, and prescribing and fitting eyeglasses and contact lenses.
- Snellen chart: A chart used to measure visual acuity, consisting of lines of letters, numbers, or symbols in standardized graded sizes, with a designated distance at which each line of letters is normally visible.
External links
- Medical encyclopedia article on Eye chart
- Wikipedia's article - Eye chart
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