Synskärpetabell

Synskärpetabell, often translated as visual acuity chart or simply eye chart, is a tool used by eye care professionals to measure a person's vision. The most common type is the Snellen chart, developed by Dutch ophthalmologist Herman Snellen in the 1860s. This chart consists of rows of letters, numbers, or symbols that decrease in size from top to bottom. Patients are typically asked to read the smallest line they can clearly identify from a standardized distance, usually 20 feet (6 meters).

The results are recorded as a fraction, such as 20/20. The top number represents the distance at which the test is performed (20 feet), and the bottom number indicates the distance at which a person with normal vision could read that same line. A score of 20/20 is considered standard or normal visual acuity. A score like 20/40 means the patient can only see at 20 feet what a person with normal vision can see at 40 feet, indicating poorer acuity. Conversely, 20/15 suggests better-than-average vision.

Variations of the synskärpetabell exist, including charts designed for individuals who cannot read, such as children, or those who speak different languages. These often use pictograms (like E, T, O) or symbols. The synskärpetabell is a fundamental component of routine eye examinations and is crucial for detecting refractive errors, amblyopia, and other vision impairments.