Eye chart

Eye chart

An eye chart is a tool used by optometrists and ophthalmologists to measure visual acuity. Eye charts are essential in diagnosing vision impairment and determining the need for corrective lenses.

A Japanese eye chart used for testing visual acuity.

Types of Eye Charts

There are several types of eye charts used around the world, each designed to test vision in different ways. The most common types include:

Snellen Chart

The Snellen chart is the most widely used eye chart in the world. It consists of 11 lines of block letters, with the top line containing one very large letter. The letters become progressively smaller as one reads down the chart. The standard testing distance is 20 feet.

LogMAR Chart

The LogMAR chart is used for more precise measurements of visual acuity. It is often used in research settings and for patients with low vision. The chart uses a logarithmic scale to measure vision.

Tumbling E Chart

The Tumbling E chart is used for patients who are illiterate or for young children who cannot read. It consists of the letter "E" in different orientations, and the patient must indicate the direction the "E" is facing.

Landolt C Chart

The Landolt C chart is similar to the Tumbling E chart but uses a ring with a gap (the "C") in different orientations. The patient must identify the direction of the gap.

Japanese Eye Chart

The Japanese eye chart, as shown in the image, is used in Japan and features symbols that are culturally relevant. It is designed to test visual acuity in a manner similar to the Snellen chart.

Usage

Eye charts are typically used in a clinical setting. The patient is asked to cover one eye and read the smallest line of letters they can see clearly. This process is repeated for the other eye. The results are used to determine the patient's visual acuity, often expressed as a fraction, such as 20/20.

Related pages

• Visual acuity
• Optometry
• Ophthalmology
• Vision impairment
• Corrective lens