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Clarksville, IN Eye Tests: Exploring the Vision Exam


Ever wonder why 20/20 is the standard for ''perfect'' vision and what it actually represents? 20/20 vision is a term used to describe a normal level of sharpness of eyesight or visual acuity measured from 20 feet away from the object. That is to say that an individual with 20/20 visual acuity will be able to clearly see an object from 20 feet away which is deemed the norm to see at that distance.

In cases of individuals that cannot see at 20 feet away, their visual acuity score is designated according to the first point at which they are able to see sharply, compared to what is normally expected. As an example, 20/100 acuity means that you must be as close as 20 feet to see what a person with normal eyesight can see at a distance of 100 feet.

It's also possible to have vision that is better than 20/20. For example someone with 20/10 vision can see sharply at 20 feet an object that most can see only at 10 feet. A number of animals particularly birds of prey have more acute eyesight compared to humans. For example, hawks have been known to have 20/2 vision, designed for spotting prey from high in the air.

A typical eye screening is performed with the use of an eye chart usually the classic Snellen eye chart developed by Dutch eye doctor, Herman Snellen in the mid-1800's. While there are now many versions, the chart generally has eleven lines with capital letters which get progressively smaller as one looks downward. The top of the chart usually shows the capital letter - ''E'' with letters being added subsequently as you move down the chart. During the eye exam, the eye doctor will examine which is the smallest line of letters you can see clearly. Your score is determined since each row is assigned a distance, with the 20/20 row usually being assigned the eighth row. In instances where the patient can't read, such as young children or disabled individuals, a variation of the chart is used called the ''Tumbling E''. At the same scale as the regular Snellen chart, this variation shows only the uppercase letter E in different rotations. The person being tested uses their hand to mimic which direction the arms of the E are facing: right, left top or bottom. In order for the results to be accurate the chart must be positioned at a distance of 20 feet from where the patient is viewing it.

Despite common conception, 20/20 vision does not indicate someone has perfect eyesight but merely that they are able to see as expected at a distance. Total eyesight includes a number of other necessary competencies such as peripheral vision, depth perception, focus for near vision, color vision and coordination between the eyes to name a few.

Although a vision screening using a Snellen chart will establish if you need eyeglasses to see far away it will not give the optometrist a complete perception of your total eye health. Make sure you still go in for an annual comprehensive eye exam which can diagnose potential conditions. Call us today to schedule a Clarksville, IN eye exam.


Our office will be opening on Monday, May 18th. We will be following all CDC guidelines as well as those recommended by our National and State Organizations including the KOA and AOA as well as the Governor of Kentucky. We will be adding to our protocol to ensure the safety of our patients and staff. Due to the recommendations, we are following, all patients will need to call from the parking lot when they arrive. We will ask you if you are running a fever, or have symptoms of COVID-19. We may even take your temperature to keep for our records. We will ask that you remain in your car until we notify you to come to our office.

All patients entering the building must wear a mask or face covering.

We ask for your patience over the next few months as we work to get our patients rescheduled that had to be canceled during the closure. We will not be working at full capacity for some time and realize this will most likely cause delays in getting people rescheduled. We will also not be taking walk-in patients and ask that you please call if you need to be seen to set up an appointment. Please know that we are doing everything we can to take care of our patients during these difficult times.

You now can order contacts from the convenience of your home on our website by clicking here.
If you do not know your current prescription, please email us at or call us at 859-271-6194.
If you have insurance you would like to use, you will need to call us and we will be happy to place the order for you and submit it to your insurance.

Thank you and we look forward to seeing you all soon,

Dr. Jason Glenn and Staff