Snellen chart
Snellen chart
The Snellen chart (/ˈsnɛlən/; Dutch: [ˈsnɛlə(n)]) is an eye examination tool used to measure visual acuity. It was named after the Dutch ophthalmologist Herman Snellen, who developed the chart in 1862.
Etymology
The term "Snellen chart" is derived from the name of its inventor, Herman Snellen, a Dutch ophthalmologist. The word "chart" comes from the Old French charte, meaning "card, map," and ultimately from the Latin charta, "leaf of paper, tablet."
Description
The Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, often the "E", "H", or "N". Subsequent rows have increasing numbers of letters that decrease in size. A person taking the test covers one eye from a specified distance, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the visual acuity in that specific eye.
Related Terms
- Visual Acuity: The sharpness of vision, usually measured with the use of a Snellen chart.
- Optotype: The characters or symbols used on a vision testing chart.
- LogMAR chart: An alternative to the Snellen chart that is often used in clinical trials and research.
- Eye Examination: A series of tests performed by an ophthalmologist or optometrist assessing vision and ability to focus on and discern objects.
See Also
References
External links
- Medical encyclopedia article on Snellen chart
- Wikipedia's article - Snellen chart
This WikiMD article is a stub. You can help make it a full article.
Languages: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
Urdu,
বাংলা,
తెలుగు,
தமிழ்,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
European
español,
Deutsch,
français,
русский,
português do Brasil,
Italian,
polski