Dyop® - Dynamic Optotype™

Helping the world see clearly, one person at a time




Personal Vision

Infant Vision

Color Screening

Professional Use


How it works







Vision is the Ultimate Illusion. 

Introducing the "revolutionary" Dyop® test method of measuring vision





Dyop Vision Webpage







Dyop Video





   Dyop Strobic Stimulus



Vision is the Ultimate Illusion.  As you read these words they are likely on a computerized display. What you are seeing as letters, lines, and shapes are really pixels of light generated by the phosphors within the surface of the screen.

Those phosphor pixels are perceived by the photoreceptors of you eye functioning as biological pixel receptors which combine their response into giving you the illusion of vision. 


Our bodies are biological machines and vision functions best as an autonomic process.  Our eyes developed as sensors for detecting motion, distance, and colors so that humans could better detect predators and game, and eat rather than be eaten.   To see most efficiently we have to be totally unaware of the mechanics of that process. 


Dyop® (short for dynamic optotype) is spinning segmented ring visual target.  Dyop gaps and segments constant rate spin creates a strobic stimulus of the photoreceptors of the eyes.  That gap/segment strobic stimulus can be used to measure acuity (visual clarity) and determine refractions. The smallest Dyop diameter ring detected as spinning creates an acuity and refraction endpoint which not only allows you to measure vision in black and white, but to also precisely measure vision in color.


When the spinning gap/segment area of a Dyop gets too small, that stimulus is too small for the photoreceptors to detect the motion.  The smallest Dyop stimulus area detected as spinning (the area of about 20 photoreceptors) creates a visual clarity threshold.  That threshold can be used by doctors to measure visual acuity and the refraction endpoint, and is significantly more precise than staring at letters.



21st Century Vision Can No Longer Rely on 1862 Technology

Our eyes developed primarily as vision sensors to detect motion, rather than just distance and color, so that humans could detect predators and game, and to eat rather than to be eaten.  Vision “standards” from 1862 are based upon the cultural ability to detect the size and difference between static letters such as “E” and “C.” As a result it tends to mistake cognition for acuity, and improperly and imprecisely “measure” vision.





We see in five variables – motion, height, width, distance, and color - NOT just in height and distance.  “Classical” 1862 based vision tests measure vision in only two variables - height and distance.  “Classical” tests are inherently imprecise because they also use cultural cognition of shapes as the benchmark rather than the physiological response of the eye.


How the Dyop test works


The bioelectrical response of the photoreceptors of the eye functions much as the pixels in a computerized video camera.  Your brain uses the response of about 100 photoreceptors for every optic nerve going to the brain to create vision and bring that image into focus.  Photoreceptors not only allow you to see in color (primarily red, green, and blue for most people), but the refresh rate of the photoreceptors and the saccade process allow you to track changes in the location of those images.  The comparative focal depth of the red, green, and blue stimulus of those images regulates the shape of the lens and the focal clarity.


However, we normally aren’t aware of that photoreceptor strobic stimulus because it would interfere with being able to see the lines and shapes as transmitted to the brain.  We literally would "see the trees rather than the forest."  The loss of cognition would be the same as if you got close enough to see the pixels on your monitor.  You totally lose the ability to see the shapes and understand the words.  It is also why fixating on a shape will literally have that shape seem to disappear as the photoreceptors lose their ability to bio-electronically respond.




Light passes through the lens

to reach the retina

Retina Structure

Epithelium  =>  4 Neural Layers  =>  Photoreceptors


Photoreceptors as Pixels


Retina Color Perception

Wavelengths of light









Light => => => Perception


Faster and more accurate visual acuity testing


When using the 1862 Snellen test, and other static image charts which derived from it, the target letters get increasingly blurry as they get smaller.  Cognition based letters become a guessing game for both the doctor and patient requiring conceptual processing by the patient as much as it does visual clarity. 


For Dyop testing, as the Dyop diameter (angular width) and the gap/segments gets sufficiently smaller, the strobic stimulus on the photoreceptors is no longer sufficiently large enough for the motion of the gap/segments to be detected. The smallest Dyop diameter (arc width) detected as moving/rotating creates a visual clarity threshold, which is used by doctors to measure visual acuity and the refraction endpoint, and is more precise than staring at letters.  The direction of rotation is irrelevant.  


The added precision and reliance upon a Dyop physiological visual response, rather than cognition of European-type letters, provides a more precise, consistent, accurate, and efficient method for measuring visual acuity. It also lets the Dyop test be used for people with limited literacy and very young children.


The History of Vision Measurement


Hundreds of thousands of years ago our eyes developed as survival tools to spot predators and game.  Thousands of years ago, visual clarity (acuity) was defined by the ability to see the nighttime gap between two of the smaller stars in the handle of the Big Dipper constellation.



Stellar Acuity

Static Letter-based Acuity

Dyop Strobic Stimulus Acuity


In 1862 Snellen defined visual acuity as the ability to identify letters, since reading had become a dominant social skill.  European vision science used the convenience of black letters on a white background as the acuity benchmark, although much of what we see is NOT in black and white.  Also, only a small portion of the earth’s population could read European letters, and that letter-based response was, and is, frequently inconsistent and imprecise.


























1862 Snellen Vision Testing


21st Century Dyop® Vision Testing


The strobic Dyop stimulus lets you sense the pixel response to the images you are seeing.


Twenty first century technology is letter-based technology.  Today’s visual acuity is primarily measured by the clarity and ability to read text on an electronic display.  Unfortunately, vision science has not kept up with the precision and demands of 21st century visual needs.



The precisely calibrated Dyop® tests are intended as a global replacement for Snellen, Sloan, and Landolt optotypes.


The personal version of the Dyop® test is intended to measure your visual clarity; however getting glasses or contact lenses requires a refraction performed by your eye doctor which CANNOT be done on a two-dimensional display such as a computer.  Measure your vision with the Dyop test using the Dyop Personal Acuity Test, and if you can’t see clearly enough, GO SEE YOUR EYE DOCTOR.


Dyop® tests are for vision screening purposes only and are NOT a substitute for an examination by a licensed vision care professional. 



“Any sufficiently advanced technology is indistinguishable from magic.”
- Arthur C. Clarke’s Third Law


As a culture we are only as good as our memory.  As a species we are only as good as our vision.


Just as the hand, held before the eye, can hide the tallest mountain, so the routine of everyday life can keep us from seeing the vast radiance and the secret wonders that fill the earth.

-          Chasidic, 18th Century


The Dyop® (Dynamic Optotype™) tests and concept are covered under U.S. Patent US 8,083,353

and International Published Patent WO 2011/022428.

For further information contact: Allan Hytowitz at Allan@Dyop.org

5035 Morton Ferry Circle, Alpharetta, GA, 30022   /   678-893-0580

Copyright©2018 Dyop® Vision Associates.  All Rights Reserved