When you visit your eye doctor for a routine eye exam, they will first assess your ability to see details at near and distant points. This is done using a printable eye chart.
Visual screening tests involve reading letters, numbers, or symbols of different sizes on a chart-like structure placed at a distance (usually 20 feet away). The results of an eye chart tell your doctor whether you have a refractive error such as:
Today, you can find free printable eye charts to test your eyesight at home before consulting your eye doctor.
In this article, we’ll review printable eye charts in detail and demonstrate how they can be valuable for home vision checks. We’ll cover the following:
- Definition and history of eye charts
- Structure of an eye chart
- The Snellen eye chart and its variants
- How to perform home vision checks
- When to consult an eye doctor
What is a Printable Eye Chart?
A printable eye chart is an optometry tool used to assess the clarity of your vision (visual acuity). The chart has rows of letters, numbers, and symbols (optotypes) of different sizes that test your near and distant vision without requiring a visit to an eye doctor.
Printable eye charts can be downloaded and printed from online sources. Some eye charts are specifically for children (pediatric eye care), while others work universally.1
History of Eye Charts
Even before the standardized eye chart was invented, doctors used customized charts to examine vision problems. Some preferred symbols or images of varying sizes, while others used words and letters.
Eye charts became even more invaluable during the peak of the Industrial Revolution, a time when good vision was vital in securing employment. The Snellen chart was the first standardized eye chart invented, thanks to Dutch ophthalmologist Herman Snellen.2
According to The New York Times, Dr. Snellen made the chart following a request by his colleague Dr. Franciscus Donders.3 Since its introduction in 1862, the Snellen eye test remains the most widespread technique for measuring visual acuity, although other variations exist.
Structure of an Eye Chart
Generally, the structure of an eye chart consists of 11 rows of capital letters (optotypes). Only the nine letters C, D, E, F, L, O, P, T, and Z are featured in a standard Snellen chart. Other visual screening charts may consist of symbols, images, and blocks of text.
The first line has one large letter, usually the “E,” while the other lines have increasing numbers of optotypes. Each row of lines also contains smaller letters than the previous one.
The inability to read a line clearly defines an individual’s level of visual acuity. The optometrist will “refract” the eye until you see the unclear letters. The readings will help your doctor determine the correct prescription for your vision.
For example, the largest letter at the top represents a visual acuity of 20/200. This means that one has to stand 20 feet away to clearly see an object that normal eyes can see from 200 feet away. According to the US Social Security Administration (SSA), if a person has a central visual acuity of 20/200 or less in the better eye while requiring a correcting lens, they are considered “legally blind.”4
The Snellen Chart and Its Variants
The developments of the Snellen chart did not stop with Dr. Snellen. Since 1862, several variations have emerged. Even so, most Snellen variations share one common feature—the rectangular shape, arising from the varying numbers and sizes of optotypes on each line.
Different eye charts may have varying numbers of lines and size progression. Today’s Snellen charts observe the following rules:
- Improved letter design
- Use of the same number of optotypes on each line
- Has a uniform 25 percent increase from line to line
The Science Behind “20/20” Vision
20/20 vision is the normal visual acuity measurement developed by Dr. Herman Snellen. Other visual acuity fractions include 20/25, 20/40, 20/50, 20/200, etc. Collectively, they’re referred to as Snellen fractions.
The first number (20) in a Snellen fraction represents the distance the person being tested is positioned from the chart. The second number represents the distance at which the smallest standardized letters are clearly visible.
Someone having 20/20 vision means they can clearly see an object positioned 20 feet away. According to research, only about 35% of adults have natural 20/20 vision.8
Alternatives and Modern Iterations of the Snellen Chart
Although the Snellen chart is considered quick, portable, affordable, and widely used, it has several drawbacks. This includes difficulty interpreting results, language barriers, and cognitive disabilities. These disadvantages have encouraged improvements in more modern charts, such as the Early Treatment Diabetic Retinopathy Study (ETDRS).
Below is a list of modern iterations of the Snellen chart:
- Tumbling E chart. Also invented by Dr. Snellen, this chart is helpful for people who can’t read letters and children unfamiliar with the alphabet. The chart uses only one letter (capital E) that faces different directions. The person being examined uses their fingers to show which direction the letter “E” is facing.
- Landolt C eye chart (Japanese vision test). Invented by Edmund Landolt, a Swiss ophthalmologist, this chart is similar to the tumbling E chart but uses Landolt’s broken ring symbols in various orientations. It measures high-contrast visual acuity and it’s helpful for illiterate or non-English speakers.
- Jaeger eye chart. Invented in 1954, this small hand-held card consists of short blocks of text in different sizes. The person being tested reads the different blocks of text to determine their visual acuity.
- LEA Symbols Chart. This test utilizes symbols and play. It was designed for young children to eliminate language barriers.6 The child is required to name the symbols and their colors to measure visual acuity.
- LogMar Chart. Invented in 1976 by the National Vision Research Institute of Australia, this chart measures visual acuity using the logarithm of the minimum angle of resolution. It enables more accurate results than the Snellen chart and is approved by the U.S. Food and Drug Administration (FDA) as the worldwide standard test for clinical eye trials. Examples of Logmar charts include the ETDRS and the Bailey-Lovie chart.
- Freiburg Visual Acuity Test (FrACT).7 This is a computerized Landolt C chart where the patient is randomly presented with Landolt C symbols in various sizes and orientations, and they respond by pressing a button based on their interpretation.
How to Do Home Vision Checks
Home vision checks can help you catch eye and vision problems early before your condition deteriorates.
You can do home vision checks on yourself or family members by downloading and printing an eye chart from a trusted online source and conducting a reading test.
Vision screening tests vary in accuracy, with some showing higher false negative results than others. For this reason, it’s important to follow the doctor’s guidelines accurately. Do the following to ensure accurate results:
- Ensure the room and Snellen chart are well-illuminated
- If you wear glasses, keep them on while you take the test
- If you have difficulty reading results, record them and reach out to your doctor
Although performing an at-home vision test under your optometrist’s directions is recommended, these tests are not alternatives to professional eye exams.
Using the Printable Eye Chart: Step-By-Step Guide
Once you’re prepared to take an at-home vision check, below is a step-by-step process of using a printable eye chart:
- Download your desired eye chart from your identified site.
- Print the eye chart full scale on regular print paper.
- Pin the chart to a wall at eye level. Ensure the room is well-lit.
- Position yourself 20 feet (6 meters) away from the chart.
- Cover one eye (keep your distance vision prescription glasses on).
- Have someone direct you by pointing at each line as you read letters aloud. They will keep track of the letters you get right.
- Continue reading row by row until you can no longer read the letters.
- Note the M-unit of the smallest line where you identified the majority of letters correctly (The reading represents your visual acuity for that eye).
- Cover the other eye and repeat steps 6-8.
Adults and older children with normal eyesight should be able to read the 20/20 line on the chart. Children 3-4 years old should be able to clearly see the 20/40 line, while 5-year-olds should be able to see the 20/30 line.
If you end up with results outside the standard, schedule an eye exam.
Alternative Visual Acuity Tests
If you’re unable to recognize letters from the eye chart, other tests can be conducted, such as:
- Counting fingers (CF vision)
- Hand movements (HM vision)
- Light perception (LP vision). If you can’t identify light, this should be recorded as “no light perception (LP)”
When to Consult an Eye Doctor
Adults and children with 20/20 vision might not require medical attention unless other underlying issues exist. However, consult your doctor if your test shows abnormal results, such as being unable to see the 20/20 line (normal vision).
Your doctor will conduct a comprehensive eye exam, which involves the vision chart and other tests to determine the overall health of your eyes.
A printable eye chart is an optometry tool used to assess the clarity of your vision (visual acuity). Most eye charts today feature rows of letters, numbers, and symbols (optotypes) of different sizes.
The Snellen chart was the first standard eye chart invented in 1862 by Dr. Herman Snellen. Since then, there have been significant improvements to enhance the accuracy and reliability of this vision test. Common variations include the Tumbling E, Landolt C, Jaeger eye chart, Freiburg Visual Acuity Test (FrACT), and LogMar chart.
Taking at-home vision checks from eye charts can assess your visual acuity. However, it should not replace your regular eye exams. Use the eye charts to check for any vision changes, but consult an eye doctor for an accurate assessment of your eye health.
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