Látásélessége

Látásélessége, often translated as visual acuity, is a measure of how clearly a person can see fine details. It is a fundamental aspect of human vision and is crucial for a wide range of daily activities, from reading and driving to recognizing faces and navigating the environment. Visual acuity is typically assessed using standardized charts, such as the Snellen chart, which displays letters or symbols of decreasing size.

The most common way to express visual acuity is as a fraction, such as 20/20 (or 6/6 in metric countries). A person with 20/20 vision can see at 20 feet what a person with normal vision can see at 20 feet. A lower number in the numerator, like 10/20, indicates better-than-average vision, while a higher number in the denominator, such as 20/40, signifies poorer vision, meaning the person needs to be at 20 feet to see what a person with normal vision can see at 40 feet.

Several factors can influence visual acuity, including refractive errors like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism, as well as conditions affecting the eye's internal structures such as cataracts or macular degeneration. Regular eye examinations are important to monitor visual acuity and detect any potential problems early. Corrective lenses, such as glasses or contact lenses, or surgical interventions can often improve visual acuity if it is reduced due to refractive errors.