Using a Dyop test to measure acuity is potentially faster, minimizes memorization, is more accurate, and is more consistent than classic (Snellen/Sloan/Landolt) letter-based tests. That precise Dyop response can be used to determine the acuity/refraction endpoint regardless of an individual’s age, language, or culture, and does not require literacy, let alone the ability to read English.

Much like the steam engine metaphor used to describes your heart as pump pushing blood through the body, or the metaphor of a computer describing how we think, the functioning of the eye is similar to the metaphor of an electronic digital camera or display.  Rather than lines or shapes, what you really see are pixels of light with the photoreceptors in the back of your eye functioning much as the pixelized receptors in an electronic camera.  The photoreceptors send that pixelized image to your brain, and giving you your sense of vision.

Vision science has not kept up with the precision and demands of 21^st century visual needs.  Acuity (visual clarity) is now primarily measured by the comfort and ability to read text, especially text on an electronic display.  Twenty-first century electronic images use rapidly scanning lines of pixels which change color and intensity to create the images we see. The photoreceptors of the eye function much like those pixels. Your brain uses the photoreceptor response to create vision and bring that image into focus.

Centuries ago acuity was measured as Resolution Acuity and the ability to see the separation of two distant points or perhaps two stars.  In 1862 acuity was re-defined as Recognition Acuity and the ability to identify European-style letters when reading became a dominant social skill.  Although much of what we see is NOT in black and white, European vision science used the convenience of black letters on a white background as the benchmark.  However only a small portion of the earth’s population could read European letters and letter-based testing was, and still is, frequently inconsistent and imprecise

Except, acuity is a not a static process but rather is a dynamic process.  The optimum size and rotation rate of a Dyop has an angular diameter of 7.6 arc minutes, with a 10% stroke width, and a 40 RPM rotation rate.  That creates a visual stimulus area (Minimum AREA of Resolution or MAR) of 0.54 arc minutes squared.  That Dyop MAR is equivalent to a stimulus rate (akin to a visual shutter speed) of 0.33 arc minutes squared per second, but the stimulus receptive area is only about 20 photoreceptors.  Since the ratio of photoreceptors to optic nerve fibers is 100 photoreceptors to every optic nerve fiber, it takes the stimulus of about 5 clusters of 20 photoreceptors to create a sufficient stimulus for an optic nerve fiber to signal the brain.