An eye sight test

An eye sight test (visual acuity test) measures how clearly you see at various distances, commonly using a Snellen chart with letters of decreasing size. It identifies refractive errors like myopia or hyperopia to determine the need for glasses or contact lenses. Normal vision is 20/20, meaning you see clearly at 20 feet what should be seen at that distance. 

Common Eye Sight Tests

Snellen Chart: The standard test where you read letters from 20 feet away.

Tumbling E Chart: Used for children or language barriers, asking the direction of the letter 'E'.

LogMAR Chart: Provides more precise measurements, often used in clinical settings.

Near Vision Chart: Handheld cards to check reading vision. 

Comprehensive Eye Exam Components

A full, professional eye exam goes beyond just visual acuity: 

Refraction Test: Determines the exact prescription for glasses.

Pupil Dilation: Drops enlarge the pupil to examine the retina and optic nerve for diseases.

Tonometry: Measures eye pressure to check for glaucoma.

Slit-Lamp Exam: A microscope examination of the eye's structures. 

At-Home & Digital Testing

WHOeyes App: A free app from the World Health Organization that checks near and distance acuity.

Online Screenings: Websites like ZEISS offer quick, basic screenings for distance and near vision, but these are not substitutes for professional exams. 

When to see an eye doctor: If you experience blurry vision, headaches, difficulty reading, or if it has been more than two years since your last exam. 

Disclaimer: Online tests are for screening purposes only and cannot detect diseases like glaucoma or cataracts.