Dyop® – short for dynamic optotype
Twenty-first century electronic images use 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.
When the moving gaps and segments of a Dyop get too small, their strobic stimulus is too small for the pixel effect to be detected by the photoreceptors of the eye. The smallest Dyop gaps and segments detected as moving create an acuity and refraction endpoint.
Dyop® – short for dynamic optotype
Twenty-first century electronic images use 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.
When the moving gaps and segments of a Dyop get too small, their strobic stimulus is too small for the pixel effect to be detected by the photoreceptors of the eye. The smallest Dyop gaps and segments detected as moving create an acuity and refraction endpoint.
Unlike static image vision tests, such as a logMAR or Snellen chart, a Dyop, or dynamic optotype, is a segmented, circular figure composed of equally spaced gap/segments which spin at a constant velocity. A patient is presented with 2 Dyops, side by side, one spinning and one static and is asked to determine the direction and/or location of the spinning Dyop.
What is detected is not so much the motion of the gaps and segments, but the strobic stimulus of the photo receptors in the eye.
Unlike static images, which get increasingly blurry as they get smaller, the spinning of the Dyop seems to disappear when the acuity threshold is reached.
As the angular width of the Dyop diameter and the gap/segments gets sufficiently smaller, the strobic stimulus is no longer sufficiently large enough for the spinning of the gap/segments to be detected.
The added precision and reliance upon a visual physiological 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 vision for children.
The Dyop® (short for dynamic optotype) is a spinning segmented circular visual target whose uniform motion, viewing distance, diameter, and color/contrast creates a strobic visual stimulus. That strobic gap/segment stimulus area utilizes the pixel-like refresh rate of the photoreceptors to measure visual clarity and refractions. The acuity endpoint is the smallest diameter Dyop image that can be detected as spinning. Using a Dyop test to measure acuity is potentially faster, minimizes memorization, more accurate, and 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.
Figure on the left illustrates the fundamental geometry of the Dyop dynamic optotype. The total circular diameter or visual angle (A), speed of rotation (B), contrasting colors, in this study black and white (C), segment angle (D), segment arc width (E), and area of each segment in arc-minutes2 (F).
The Dyop® (short for dynamic optotype) is a rotating segmented circular gap/segment image whose uniform motion, viewing distance, diameter, and color/contrast creates a strobic visual stimulus. That strobic gap/segment stimulus area utilizes the pixel-like refresh rate of the photoreceptors to measure visual clarity and refractions. The acuity endpoint is the smallest diameter Dyop image that can be detected as rotating. Using a Dyop test to measure acuity is potentially faster, minimizes memorization, more accurate, and 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.
Figure on the left illustrates the fundamental geometry of the Dyop dynamic optotype. The total circular diameter or visual angle (A), speed of rotation (B), contrasting colors, in this study black and white (C), segment angle (D), segment arc width (E), and area of each segment in arc-minutes2 (F).
In 1862 visual acuity was re-defined as the ability to identify letters when reading became the dominant social skill. However, European vision science used the convenience of black letters on a white background as the benchmark, although much of what we see is NOT in black and white, only a small portion of the earth’s population could read European letters, and letter-based testing was, and is, frequently inconsistent and imprecise.
Today’s visual acuity is measured by the comfort and ability to read text, especially text on an electronic display. However, vision science has not kept up with the precision and demands of 21st century visual needs.
Figure on the right shows three Dyop optotypes on the screen with the largest on the left and the smallest on the right. In the actual test, each would be turning in a random direction. In this configuration the subject reports which direction the middle Dyop is turning. As threshold is reached, in the largest Dyop (left), motion is seen, the yellow highlighted middle sized Dyop appears to stop moving or “twinkles”, and the right smallest Dyop clearly no motion is reported. In typical acuity threshold ranges, the left could be 20/14, the middle 20/13, and right 20/12.
In 1862 visual acuity was re-defined as the ability to identify letters when reading became the dominant social skill. However, European vision science used the convenience of black letters on a white background as the benchmark, although much of what we see is NOT in black and white, only a small portion of the earth’s population could read European letters, and letter-based testing was, and is, frequently inconsistent and imprecise.
Today’s visual acuity is measured by the comfort and ability to read text, especially text on an electronic display. However, vision science has not kept up with the precision and demands of 21st century visual needs.
Figure on the right shows three Dyop optotypes on the screen with the largest on the left and the smallest on the right. In the actual test, each would be turning in a random direction. In this configuration the subject reports which direction the middle Dyop is turning. As threshold is reached, in the largest Dyop (left), motion is seen, the yellow highlighted middle sized Dyop appears to stop moving or “twinkles”, and the right smallest Dyop clearly no motion is reported. In typical acuity threshold ranges, the left could be 20/14, the middle 20/13, and right 20/12.
Each individual subject and their raw data from the Dyop with blur(orange); Mean = 0.873 Variance = 0.035.
Green graph shows each individual subject and their raw data from the Sloan VA with blur; Mean = 0.368 Variance = 0.193.
We noticed that with the Dyop we were able to get to endpoints very quickly, and when plotted, the data showed a marked reduction in variability with far more linearity. At times, when looking at averaged data the richness of clinical observations made gets obfuscated.
We noticed some outlier lines which seemed to indicate that going from one level of blur to another, where we expected a decrease in visual acuity, that we observed an increase. At the lowest part of the graph, a green line can be seen shifting downward (better visual acuity) towards +2.00 on the X-axis. Based on this finding we looked at individual sets of data to determine
how often this occurred.
In the Sloan VA testing, 31 of the 162 subjects had these anomalies. 15 of
them had a recording of a better level of visual acuity at the +4.00 level of blur than at +3.00. 12 of them had a recording of a better level of visual acuity at +3.00 blur over the +2.00 blur. Four subjects had the same exact level of visual acuity recorded at two different levels of blur, either at both the +2.00 and +3.00 or the +3.00 and +4.00 level of blur.
With the Dyop there were only three of 162 such instances. With one
subject the visual acuity recorded was the same with the +3.00 and +4.00 blur.
With one subject it was better with the +4.00 vs. the +3.00 blur and with one
other subject it was better at the +3.00 than at the +2.00 level.
Dr. Paul Harris, SCO.
Each individual subject and their raw data from the Dyop with blur(orange); Mean = 0.873 Variance = 0.035.
Green graph shows each individual subject and their raw data from the Sloan VA with blur; Mean = 0.368 Variance = 0.193.
We noticed that with the Dyop we were able to get to endpoints very quickly, and when plotted, the data showed a marked reduction in variability with far more linearity. At times, when looking at averaged data the richness of clinical observations made gets obfuscated.
Figure above shows each individual subject and their raw data from the Dyop with blur(orange); Mean = 0.873 Variance = 0.035.
Green graph shows each individual subject and their raw data from the Sloan VA with blur; Mean = 0.368 Variance = 0.193.
We noticed some outlier lines which seemed to indicate that going from one level of blur to another, where we expected a decrease in visual acuity, that we observed an increase. At the lowest part of the graph, a green line can be seen shifting downward (better visual acuity) towards +2.00 on the X-axis. Based on this finding we looked at individual sets of data to determine
how often this occurred.
In the Sloan VA testing, 31 of the 162 subjects had these anomalies. 15 of
them had a recording of a better level of visual acuity at the +4.00 level of blur than at +3.00. 12 of them had a recording of a better level of visual acuity at +3.00 blur over the +2.00 blur. Four subjects had the same exact level of visual acuity recorded at two different levels of blur, either at both the +2.00 and +3.00 or the +3.00 and +4.00 level of blur.
With the Dyop there were only three of 162 such instances. With one
subject the visual acuity recorded was the same with the +3.00 and +4.00 blur.
With one subject it was better with the +4.00 vs. the +3.00 blur and with one
other subject it was better at the +3.00 than at the +2.00 level.
Dr. Paul Harris, SCO.
Much like using the metaphor of the steam engine to describe your heart as pumping blood through the body, or using a computer to describe how we think, the functioning of the eye is similar to the metaphor of an electronic digital camera.
The photoreceptors in the back of your eye function much like the pixelized receptors in that electronic camera. What you really see (if you can see clearly) are really pixels rather than lines or shapes. The photoreceptors in your eyes send that pixelized image to your brain which uses it to bring the image into focus and give you your sense of vision.
The focus of light and images on the retina (normally) are the result of the biological lens changing its shape to adjust the focal length of light. The focus of images is regulated by the retina cone photoreceptors which are (normally) specifically sensitive to red (L), green (M), and blue (S) wavelengths of light, however, the red, green, and blue colors focus at different depths within the retina.
The disparity of the focal depth for those colors regulates the shape and focus of the biological lens. The layers of the retina neural ganglia function as a biological circuit board to combine and filter the responses of around 100 photoreceptors into the combined response that is both sent to the brain via one optic nerve and used to provide chromatic triangulation to control the focal length and adjust acuity as well as increase the eye’s sensitivity for detecting motion.
The photoreceptor pixelized processing in our eyes interprets what we see as a contiguous image, similar to the pixelized stimulus of a TV, computer display, or digital camera. Only when we get close enough to the image do we become aware of those individual pixels.
Those electronic pixels are similar to the Dyop® gap/segment stimulus. When the Dyop® gap/segment stimulus area gets smaller, or is viewed at a sufficiently farther distance, our eyes no longer detect the motion of the gap/segments, and merge them into the illusion of a continuous image. The perception of the smallest strobic gap/segment Dyop® stimulus and the photoreceptor refresh rate creates the acuity endpoint detection response.
The photoreceptor pixelized processing in our eyes interprets what we see as a contiguous image, similar to the pixelized stimulus of a TV, computer display, or digital camera. Only when we get close enough to the image do we become aware of those individual pixels.
Those electronic pixels are similar to the Dyop® gap/segment stimulus. When the Dyop® gap/segment stimulus area gets smaller, or is viewed at a sufficiently farther distance, our eyes no longer detect the motion of the gap/segments, and merge them into the illusion of a continuous image. The perception of the smallest strobic gap/segment Dyop® stimulus and the photoreceptor refresh rate creates the acuity endpoint detection response.
