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Focusing on Visual Acuity


Everyone has heard the expressions visual acuity and twenty-twenty vision. As common as these terms may be, do you actually know their meaning?

20/20 vision actually refers to the sharpness of vision from 20 feet away. If you've been told you have 20/20 vision, it means that from a distance of twenty feet you're able to clearly see what should be seen from that distance. You may not know this, but 20/20 is really just a standard measurement. Many people have eyesight better than 20/20; for instance, some people have 20/15 vision, so what they would be able to see at 20 feet, a person with normal vision might only be able to discriminate from 15 feet.

Your eyes are tested separately. During the part when you're asked to correctly read letters from the eye chart, the smallest letters you can clearly see determine the visual acuity in the eye being tested.

20/20 eyesight actually doesn't mean your vision is perfect, and that's because it only assesses how sharply you see at a distance. There are several other important components to seeing well; being able to focus on close objects, contrast sensitivity, peripheral awareness, eye coordination, depth perception and color vision - these all contribute to your overall ability to see. Also, someone who has 20/20 vision can have unhealthy eyes. Even people who have damage to the nerves within their eyes due to glaucoma, diabetes, high blood pressure, or a range of other diseases might still have 20/20 vision without needing to wear eye glasses. This is why your eye care professional always performs a comprehensive eye exam, as opposed to just a regular eye chart exam.

So the next time you have a comprehensive eye exam, you'll know exactly why you're being told to read letters off an eye chart, and more!

Dear Patients,

Dr. Lewis Eye Care has made the difficult choice to temporarily close due to the COVID-19 virus pandemic based on the recommendation of the CDC. We cannot perform eye exams while maintaining social distancing, so continuing to see patients at this time could contribute to the spread of the virus.

Our initial plan had been to reopen Monday April 6th. However, as we get closer to that date it is becoming apparent that we may have to be closed for a longer, indefinite period of time.

If you are having an urgent eye health issue, there are some clinics in our area that are seeing patients for emergencies during shorter business hours. You should call ahead to those offices before going to their clinic, as their availability might change day by day. Those clinics could include Vancouver Eye Care at 360-823-2020, Peace Health Medical Group Eye Care at 360-514-7210, and Vancouver Clinic in Salmon Creek at 360-882-2778.

If you need a glasses or contact lens prescription emailed to you from our office, click on the Contact Form link, type in your name, email, and what you are requesting, and we will email you the information you need as soon as we can.

Thank you for your understanding, and please stay healthy during this difficult time.


Dr. Scott Lewis, OD