Stereo Acuity and Summation: The Advantage of Two Eyes



Frequently during eye exams, patients will notice they see better on the eye chart with two eyes open, and will try to sneak around the cover paddle to get to two eyes ASAP. We are well familiar with the mathematical rule, the whole is not greater than the sum of its parts, but eyes are an exception to this rule. Summation describes the brain’s ability to add the vision from each eye in order to produce better visual acuity than one eye provides alone. As a result, the exam chart may read something like this:

20/20 Right(OD), 20/20 Left(OS), 20/15 Both(OU)

Stereo acuity, or 3-D vision, is another binocular (when two eyes work together) visionprocess. Because the eyes are physically separated by space, they view object from a different angle, and the brain can then interpret depth. For example, those of you without stereo cannot appreciate 3-D puzzles and movies.

Eye conditions that can limit summation and stereo acuity include refractive error, amblyopia, monovision, esotropia, exotropia and a host of possible medical eye concerns.

We advise all minions, one and two-eyed, to have regular eye exams.

From the eye doctors, opticians and staff at Rinkov Eyecare Centers. We’ve provided comprehensive eye exams, contact lenses, eyeglasses, sunglasses and medical treatment of eye disease such as cataract treatment in Columbus, Ohio, for over 35 years. Come see an optometrist at one of our Columbus locations – Downtown, West, East, Westerville, Dublin, Bexley, Worthington and Nationwide Plaza.

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