You could be asked to read an eye measurement chart during your check-up with the eye doctor. The chart gauges your sharpness of vision, or visual acuity. Your eye doctor will use the results to determine if you need glasses or contacts if you do not currently use them. The outcomes of wearing corrective lenses will indicate whether your prescription needs to be adjusted.
Eye measurement chart
The classic eye chart, with its rows of large letters at the top that progressively get smaller as you move down, is one feature of optometry that almost everyone is familiar with.
However, how well-versed are you in this eye chart? Are eye charts identical? What are these eye charts used for? When were they released?
This is all the information you want on eye charts and more!
What is an eye chart?
One tool your eye doctor uses to evaluate your vision is an eye chart.
Your optometrist will measure the prescription that will provide you with the clearest, most comfortable vision before determining whether you have myopia (nearsightedness), hyperopia (farsightedness), presbyopia (age-related farsightedness), or astigmatism based on how well you can see different parts of the chart.
Do Eye Measurement Chart All Look the Same?
There are several kinds of eye charts. While some charts use text, others employ images or patterns. Some charts may be used by eye care professionals to measure near vision, while others may be used to measure distant vision.
While some eye charts are specifically designed for kids, others are suitable for both adults and kids. But the most widely used and well-known is the Snellen eye chart.
The Snellen Eye Chart: How to Use It
The Snellen eye measuring chart usually shows eleven rows of capital letters. One extremely enormous letter appears in the first line. The quantity of smaller-sized letters increases with each subsequent row.
Without your contacts or spectacles, you read from the Snellen chart while standing 20 feet away. You read the tiniest line of letters you can see while covering one eye.
After that, you cover the other eye and repeat. In certain offices, the chart is seen through a mirror.
This indicates that fewer than 20 feet of space is needed to conduct the test. Using a mirror or not has no effect on the outcome.
Your visual acuity is normal if you have 20/20 vision.
The top number indicates how far away you are from the chart in feet. When you read a line properly, the bottom number indicates how far someone with normal vision can see it. A person with 20/20 vision can see what an ordinary person can see on an eye chart at a distance of 20 feet.
The Snellen Eye Chart’s Background
The Snellen eye measurement chart was created in the 1860s by Dutch ophthalmologist Hermann Snellen. He worked with Dr. Franciscus Donders. By asking individuals to examine a chart on a wall and describe what they could see, Donders was able to detect vision issues.
Additionally, Dr. Snellen developed a chart known as the “Tumbling E” eye chart. It can be used by those who are illiterate and by young children who are unfamiliar with the alphabet.
This chart employs a capital letter E that faces in various orientations rather than utilizing distinct letters. The test taker indicates the direction that the E’s “fingers” are pointing with their fingers.
The eye chart was created during a period when the industry was expanding quickly.
People in a variety of occupations, including manufacturing workers and railroad engineers, need strong vision.
How Eye Exams Use the Snellen Chart
One huge letter makes up the first row of the typical Snellen chart, which has eleven rows of capital letters. The letters get smaller as you proceed down the chart.
Your eye doctor will ask you to sit or stand 20 feet away from the chart and remove any glasses or contacts you may be wearing. After that, you will be asked to read from the chart.
You will be instructed to read aloud the tiniest line of letters you can see with just one eye while covering the other eye. After that, you will be instructed to cover the other eye and repeat the action.
Many companies may not have 20 feet of space; therefore, you will be asked to look at the chart through a mirror. This gives you the same visual experience as if you were twenty feet away.
Therefore, if you have 20/20 vision, you can see on an eye chart what the typical person can see from 20 feet away. However, if you have 20/200 vision, which is the legal definition of blindness, you can only see clearly from 20 feet away what someone with normal vision can see clearly from 200 feet away.
What Time Is Best for an Eye Exam?
Your visual acuity is measured as part of an eye test. At age 40, the American Academy of Ophthalmology advises getting a baseline eye checkup. This is when visual abnormalities or early illness symptoms might appear. The eye doctor cannot determine if you have a retinal issue or an eye condition like glaucoma without using eye charts. Additionally, they don’t evaluate other visual issues like side vision loss.
In what ways do you keep your eyes healthy?
After eye measurement chart, Don’t take advantage of the one pair of eyes you have!
Follow these guidelines to maintain good eye (and body) health. These consist of:
- Eating a diet rich in fruits, vegetables, and fiber that is well-balanced.
- Drinking enough of water to maintain hydration in your body and eyes.
- Abstaining from smoking and secondhand smoke.
- Putting on sunglasses to shield oneself from ultraviolet (UV) radiation.
Which medical disorders can be identified by an eye exam?
A thorough eye exam can identify underlying illnesses including diabetes, high blood pressure, high cholesterol, tumors, autoimmune diseases, and thyroid issues that can endanger your vision and eye health.
For this reason, it’s crucial to have your eyes examined on a regular basis. Your quality of life will improve, and the result will be better the earlier you receive a diagnosis and treatment.
