What does 20/20 vision mean?
Results from an eye exam using the Snellen chart are conveyed as a fraction that has a 20 in the numerator, or top number, and a value between 10 to 600 in the denominator, or bottom number. The denominator refers to the distance from where a person with normal vision could clearly read the symbols on the chart. A visual acuity result that has a denominator larger than 20 indicates a visual deficit. 20/20 vision is considered “normal”, and the higher the denominator, the worse the vision.
It’s Important to Have Annual Eye Exams.
During a complete eye exam, our eye doctors in North Columbus, Gahanna or Dublin, OH will not only determine your prescription for eyeglasses or contact lenses, but will also check your eyes for common eye diseases, assess how your eyes work together as a team and evaluate your eyes as an indicator of your overall health.
A comprehensive eye exam includes a number of tests and procedures to examine and evaluate the health of your eyes and the quality of your vision. These tests range from simple ones, like having you read an eye chart, to complex tests, such as using a high-powered lens to examine the health of the tissues inside of your eyes.
Eyecare experts recommend you have a complete eye exam every one to three years, depending on your age, risk factors, and physical condition.
Pediatric Eye Exam at Pearle Vision Grove City, OH & Gahanna
Some experts estimate that approximately 5% to 10% of pre-schoolers and 25% of school-aged children have vision problems. According to the American Optometric Association (AOA), all children should have their eyes examined at 6 months of age, at age 3 and again at the start of school. Children without vision problems or risk factors for eye or vision problems should then continue to have their eyes examined at least every two years throughout school.
Children with existing vision problems or risk factors should have their eyes examined more frequently. Common risk factors for vision problems include:
- premature birth
- developmental delays
- turned or crossed eyes
- history of eye injury
- other physical illness or disease
The AOA recommends that children who wear eyeglasses or contact lenses should have their eyes examined at least every 12 months or according to their eye doctor’s instructions. Read more about Pediatric Eye Exams.
Annual Eye Exam at Our North Columbus Optometrist
The AOA also recommends an annual eye exam for any adult who wears eyeglasses or contacts. If you don’t normally need vision correction, you still need an eye exam every two to three years up to the age of 40, depending on your rate of visual change and overall health. Doctors often recommend more frequent examinations for adults with diabetes, high blood pressure and other disorders, because many diseases can have an impact on vision and eye health.
If you are over 40, it’s a good idea to have your eyes examined every one to two years to check for common age-related eye problems such as presbyopia, cataracts and macular degeneration. Read more about Vision After 40.
Because the risk of eye disease continues to increase with advancing age, everyone over the age of 60 should be examined annually. Read more about Vision After 60.
Vision Testing with Eye Charts
How does it work?
In general, eye charts are the golden standard used to measure visual acuity. To test vision quality, our optometrists in Grove City, OH, will ask you to read an eye chart during your eye exam. There are many versions of eye charts, with the Snellen chart being the most common.
The chart will be mounted at a standardized distance from where you are seated, and you’ll need to read rows of letters and/or numbers aloud. If you wear eyeglasses or contact lenses, you’ll have to remove them before this eye exam. With the Snellen chart, patients are placed 20 feet away, and each eye is tested separately for distance vision. The symbols get progressively smaller with each successive row, and it’s important for you to keep reading them until they are too small to identify. Your visual acuity refers to the smallest symbols that you are able to see clearly from that distance.
After your vision quality without eyeglasses or lenses is determined, you will be asked to repeat the test with eyewear on, which should normalize your visual acuity. This is how your accurate vision prescription is confirmed or determined.
Charts other than the Snellen chart will be used to figure out your vision in different situations, other than viewing from a distance. For example, the Rosenbaum or Jaeger chart may be used to test near vision when diagnosing presbyopia.