Dyop® - Dynamic Optotype™

Helping the world see clearly, one person at a time




Personal Vision Test

Children’s Vision Test  

Color and Dyslexia Screening

Professional Test




Visual Impairment





Not everyone sees COLOR the same way.


The Dyop® test enables measuring acuity in COLOR as well as in Black and White.

Color perception affects your visual skills and personality.


Dyop® Professional Color  Test


FREE Dyop Color Screening Test



Dyslexia has little to do with intelligence, or limited intelligence.  Instead, it seems to be a caused by visual stress which reduces the ability to read letter-based words. 

There likely is a correlation between color perception and symptoms of dyslexia, migraines, and epilepsy.  Dyop® Color Screening may be a useful indicator of   potential symptoms of dyslexia, migraines, and epilepsy.


Color_Perception and Dyslexia - SandraStark


Other Research Articles:

Harris – Colored Contacts Paper


Harris – Colored Contacts Poster


Chromatic Modulation Symptoms


Correlation of Reading Speed to L/M Ratios




Visual acuity (and accommodation) is regulated by the comparative responses by the cone-shaped Red (L), Green (M), and Blue (S) cone photoreceptors in your eyes.  The cone photoreceptors function as pixelized biological receptors of color much like those of a digital video camera.  The cone photoreceptors also use the focal length disparity between Red and Green to adjust the shape of the lens and bring the overall image into focus (accommodation). 


Green Focused Vision (GFV)

50% red and 45% green photoreceptors

Red-Focused Vision (RFV)

75% red and 20% green photoreceptors


Retina Structure

Epithelium  =>  4 Neural Ganglia Layers  =>  Photoreceptors


Retina Color Perception















Wavelengths of light


There are approximately 100 photoreceptors for every optic nerve fiber.  The retina neural ganglia layers “process” those photoreceptor responses in clusters of about 20 photoreceptors as a biological circuit board with the emphasis on patterns of motion and proximity.  Static photoreceptor stimulation tends to be ignored or increase visual strain.  The difference in the perception of color allows the eye to use those colors to create chromatic triangulation to regulate the focal length of the lens, with Blue, Green, and Red at increasing focal depths.


Acuity endpoints vary as to specific colors and visual perception group.

Smaller arc width or Snellen ratio indicates better acuity.

The above color/contrast permutations are included in the Dyop professional test as part of the Chart2020 vision test platform.


Dyslexia also seems to be associated with HOW we see colors.

Your Red/Green ratio determines HOW you see and WHAT you see.

(Ask your friends what THEY see.)

Green-Focused Vision (GFV)

The Dress is Gold/White

More stable near-image vision

Red-Focused Vision (RFV)

The Dress is Blue/Black

More stable distance-image vision


One of the possible causes of symptoms of dyslexia, migraines, and/or epilepsy is the Red Focused Vision (RFV) and near vision stress caused by having a higher ratio of Red to Green photoreceptors (75% red and 20% green photoreceptors).  That Red Focused Vision increases the visual stability of distance images but also decreases the stability of the lens when it needs to focus on near images.   That visual dissonance at near distances is associated with dyslexia-type symptoms.  Green Focused Vision (GFV) - with 50% red and 45% green photoreceptors enables a more stable close visual image.


Photoreceptor Distribution

Vision / Photoreceptor Ratio Type

Red % (L)

Green % (M)

Blue % (S)

Green-Focused Vision (GFV)




Red-Focused Vision (RFV)





Red Focused Vision (RFV), enables a more stable distance image which facilitates spotting predators and game and seeing pictographs as words, rather than words as letter-based combinations, and may contribute to symptoms of dyslexia, migraines, and epilepsy.


Dyop color/contrast screening test


To screen for the color vision group, select the FREE Dyop® Color Screening Test above for use on a PC, iPad, or SmartPhone (iPhone or Android).  Move away from the identical-diameter spinning Dyop® rings until you CAN ONLY detect either the spinning Green-on-White Dyop® OR the Blue-on-Black Dyop®.  You can also use the Minus (-) or Plus (+) symbols to make the spinning rings smaller or larger.  For a proper color perception screening, the test should be taken without wearing your glasses or other corrective lenses. 


If you can detect only the spinning Green Dyop® when the spinning rings get sufficiently smaller or further away, you have Green Focused Vision (GFV).   If you can detect only the spinning Blue Dyop® ring you have Red Focused Vision (RFV).   The higher-red ratio (75% red and 20% green) of Red Focused Vision (RFV) contributes to an unstable near vision but enables you to better see pictographic words rather than letter-based word combinations.)


The spinning Dyop® color images below are for use on a Smart Phone or tablet


















When you move away from the screen, detecting spinning of ONLY the Blue-on-Black Dyop® is potentially indicative of Red Focused Vision and symptoms of dyslexia, migraines, or epilepsy. You may also use the colored spinning GIF files on this webpage (above) by moving away from the spinning images and noting, when they are sufficiently smaller, as to whether you CAN ONLY detect spinning of the Green-on-White Dyop® OR the Blue-on-Black Dyop®.   



The following is a Static image screenshot of the Dyop® Color/Contrast Screening Test.




Red-Focused Vision contributes to an unstable near-image.

That unstable near-image is symptomatic of dyslexia, and likely a catalyst for migraines and epilepsy.



- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


There are multiple forms of dyslexia as well as varying symptoms


See: https://aceitnow.wordpress.com/2013/02/07/types-of-dyslexia/

Note that Red Focused Vision (RFV) may NOT seem to be a factor with Dyscalculia (number dyslexia).


Dyops® create a unique, and previously unavailable, ability to understand and experiment with visual perception.  The Dyop® color/contrast test uses the Red Focused Vision (RFV) versus Green Focused Vision (GFV) response to significantly correlate to symptoms of dyslexia, migraines and epilepsy.



Previous Color/Contrast Research

Using the ability of a Dyop test to determine precise acuity endpoints, a matrix of color/contrast permutations was created to validate those specific color acuity endpoints.



Dyop Color Matrix with 60 color/contrast permutations




Dyop Color Matrix with 60 color acuity endpoints - visual threshold endpoint distances in feet.


It was subsequently realized that the color/contrast acuity endpoint for some individuals with dyslexia significantly differed from individuals WITHOUT associated symptoms of dyslexia, migraines, or epilepsy.



31 permutations of the Dyop Color Matrix for dyslexia screening


The 31 color/contrast permutations became the basis for a Dyop duo test which can be used as a ten second color vision group screening test for potential symptoms of dyslexia, migraines, and epilepsy.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


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


Your comments, feedback, and test results would be greatly appreciated.  Please send them to Allan@Dyop.org.



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   /   404-281-7798

Copyright©2021 DyopVision™ Associates.  All Rights Reserved.