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Dyop® - Dynamic Optotype™ Helping the world see clearly, one
person at a time |
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Vision Scientists and
Eye Care Professionals have known for decades
that the Snellen test is
inaccurate and inconsistent.
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"Results confirm the arbitrary nature of the Snellen fraction
and warn about the accuracy of visual acuity determined by using charts of
different letter types, calibrated by Snellen's
system." A. Medina, B. Howland - Ophthalmic and Physiological Optics,
January 1988 “A novel
high-frequency visual acuity chart” https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1475-1313.1988.tb01076.x The Dyop® test
optimize the refraction and acuity processes to generate a more precise and
consistent refraction to reduce both
patient and refractionist visual stress.
In an era where SmartPhones and
computers are ubiquitous, the errors inherent in Snellen testing are no
longer acceptable. Preliminary studies indicate that Dyop®
acuity tests: ·
are more accurate than Snellen/Sloan tests, ·
are more consistent than Snellen/Sloan tests, ·
are potentially faster to use than Snellen/Sloan tests, ·
maintain greater precision as refractive power increases, ·
inherently avoids overminused and underminused refractions, ·
minimize optotype fixation and
decision fatigue, ·
minimize image memorization, ·
do not require the ability to read to measure visual acuity, ·
potentially save doctors and patients’ time and money in determining
visual needs. Clinical results demonstrate improved Dyop precision,
consistency, efficiency, and reduced excess minus. https://www.dyop.info/documents/Snellen_vs_Dyop_Refractions-Sanni.pdf Dyop® acuity tests are intended to be a more precise and faster to use
replacement for Snellen, Sloan, and Landolt visual acuity/refraction
tests.
Dyop® tests use apparent motion detection from the strobic
stimulus and refresh rate of the photoreceptors to determine the visual
acuity and refraction endpoints. Snellen
letters are culturally derived, NOT
proportional, and do NOT
provide a consistent basis for determining visual acuity. As a
result, Dyop® tests are more accurate and efficient than
the 1862 classic Snellen test, and create a visual acuity test based on physiology rather than
subjective and imprecise cognition. Dyop® tests
enable patients to have a visual acuity endpoint which avoids overminused
refractions which seem to be inherent with static image fixation. It is typically difficult for patients to
perceive when optotypes are "too crisp" (over- minused), despite
the discomfort and visual stress, which is one of the inherent inadequacies
with Snellen and other static image tests.
Dyop® tests determine visual acuity based upon photoreceptor
physiology with a precision (approximately +/- 0.04 diopters) not previously available with
traditional static image visual acuity tests.
Unlike static image tests, which may be dependent upon cognition as
much as they are for visual acuity, Dyop®
tests also maintain a higher level of
accuracy as visual acuity decreases with increased blur.
Is
1862 Vision Technology Making
21st
Century Patients Blinder?
The Dyop strobic stimulus has greater precision and less variance than
static visual targets The increased precision
and consistency and “resolution acuity” of Dyop tests are intended as
a global replacement for static letter-based “recognition acuity” tests such as
Snellen, Sloan, and Landolt optotypes, and can provide a more
universal and efficient method of vision measurement.
The
2013 projected Sloan optotypes are “fuzzier” than the 2013 computer generated
Sloan optotypes, and thereby give a “fuzzier” acuity response. The
0.54 arc minutes squared Dyop® visual stimulus area (the arc width of the
gap/segments) is smaller and inherently more precise than the 1.0 arc minute
squared visual stimulus area (the “Minimum Area of Resolution”) of
Snellen/Sloan/Landolt optotypes. The
0.54 arc minutes squared Dyop® visual stimulus area correlates to about 20
photoreceptors.
Fixating on static Snellen/Sloan images also
increases accommodative stress, which leads to an overminused acuity response
and possible overminused refraction. The visual dissonance/stress from an
overminused refraction is frequently a major reason for patients’
complaining about their lenses and/or not wearing their lenses at all.
The
Dyop® Acuity/Refraction Test can be
used on virtually any personal computer system with minimal setup-up and
training. Dyop®
vision testing should increase the accuracy of prescriptions, let patients
more easily know when their vision is not proper, maintain higher
practitioner testing consistency, and potentially save doctors and patients’
time and money when getting their vision checked. |
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The Dyop®
concept is revolutionary, both
literally and culturally. Previous
static methodologies for measuring visual acuity were culturally based and a
combination of the perceptual guesses of the subject and the observational guesses
of the examiner. The 1862 Snellen
test, and the 1888 Landolt ring as an attempt at a “culturally neutral” test,
use static images with a limited precision increment range that is no longer
adequate for a society where much of the day is spent looking at the
precision of a computerized display and/or regularly travelling at speeds
greater than 55 miles per hour (88.5 kilometers per hour). Snellen letters are culturally derived, NOT proportional, and do NOT provide a consistent basis for
determining visual acuity: Snellen
tests also ignore the fact that the visual stimulus is the “Minimum AREA of Resolution” rather
than the “Minimum ANGLE of Resolution.” Visual acuity
measurement in increments of +/- 0.25 diopters was acceptable and adequate in
1862 because of the difficulty of making lenses more precisely than +/- 0.25
diopters. Visual testing in increments
of +/- 0.25 diopters was also adequate because of the small percentage of the
population able to read, or needed to be able to read. Varying Difficulty of Snellen Letters and Common Errors in Amblyopic
and Fellow Eye PDF File http://archopht.ama-assn.org/cgi/content/abstract/129/2/184 http://archopht.jamanetwork.com/article.aspx?articleid=426887 Snellen test responses also are NOT equivalent to the responses from
the academically preferred Landolt ring test. Because of the increased cognition factor inherent in the
non-uniformity of the Snellen letters, for them to be equivalent to the
5 arc minute size of Landolt rings, Snellen letters should actually be only
4.25 arc minutes in size (15% smaller) and NOT the currently accepted 5.0 arc
minute height. Correlation of Optotypes with
the Landolt Ring PDF file PDF file Note:
Dyop® tests are for vision screening purposes only and are NOT a
substitute for an examination by a licensed vision care
professional. |
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©2022 DyopVision™
Associates. All Rights Reserved.