How Sharp Is Your Vision? Here’s How It’s Tested

Acuity of vision, also termed visual acuity, describes the clearness of your vision when measured from 20 feet away. Acuity of vision is the most common medical measurement of your eyes’ visual capability without help from eyeglasses or contact lenses. An ophthalmologist uses these measurements to determine the lens strengths of their patients’ eyewear. 

At the office of Glaucoma Consultants of St. Louis, we are experts at helping our patients with their eye health. We give all of our patients as much time as they need to understand their treatment options. From diagnosis to treatment, we’re here for you every step of the way.

If someone’s visual acuity measurement is 20/20, then he (or she) has a good quantity of detail of an object that’s 20 feet away. If another person’s measurement is 20/40, he can see the same amount of detail from 20 feet away as the person with 20/20 vision would see from a distance of 40 feet. Only 35 percent of adults have 20/20 acuity without help from glasses, contacts or laser surgery. People with 20/200 vision are considered legally blind. Many people can have 20/20 vision with help from corrective lenses.

Having 20/20 vision doesn’t mean your sight is perfect, however. Vision power also encompasses your eyes’ coordination, depth perception, color visualization, peripheral vision and ability to focus. Children’s visual acuity should be tested regularly to monitor the development of their vision. 

Most ophthalmologists use two types of visual acuity exams: the Snellen and the Random E. 

• The Snellen chart is 11 rows of capital letters. The top line has one very large letter. Each subsequent row has more letters that get increasingly smaller. You cover one eye and call out the smallest line of letters you can see clearly. 
• The Random E test has only a capital letter E and is for children and adults who have difficulty identifying letters. ‌As the chart progresses from top to bottom, each E faces up, down, left or right and shrinks in size. The patient identifies the directions of the Es until they can’t be seen clearly. 

Glaucoma Consultants of St. Louis’s professional team is made up of friendly specialists who are eager to help you feel comfortable and relaxed while receiving the best treatment. For more information about our office and how we can help you, please don’t hesitate to schedule an appointment.

By Glaucoma Consultants of St. Louis

October 25, 2022