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Controlling Optical Wavelengths
to Create a Comfortable
Field of Vision— NeoContrast™ Technology —Tomoya Handa, Ph.D.
Professor of Orthoptics and Visual Science,
School of Allied Health Sciences, Kitasato University

optical monthly Gankyo, February 2020, p.70-73

Quality of View (QoV) for all*QoV (Quality of View) is a measure of quality and satisfaction in all areas related to eyes and eyesight in our lives.
The term encompasses vision optimization and comfort, ocular health, and measures to prevent optical diseases.

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Controlling Optical Wavelengths
to Create a Comfortable
Field of Vision— NeoContrast™ Technology —of Orthoptics and Visual Science,Tomoya Handa, Ph.D. Professor
School of Allied Health Sciences, Kitasato University
Light is an essential item for our everyday lives and forseeing things. However, this does not mean that themore light we have, the better we can see things. The
role of the eye is to capture light and pass a signal onto
the visual area of the brain, but photic stimulation isconstantly received from extremely far-ranging lightwavelength and quantity whether indoors or outdoors.
To capture light and achieve a comfortable range ofvision, it is necessary to pursue both aspects of“refraction” (function of capturing light and forming a
sharp image on the retina) and “optical wavelengthcontrol” (function of cutting a certain opticalwavelength to improve visual quality and protect theeyes). With regard to the former; the function(refraction) of capturing light from a spectacle lens anddelivering sharp images to the retina is already known
greatly throughout society. Could the same be said, on
the other hand, of the former – optical wavelength

control ? Looking at
it from a perspectiveof protecting the eyesfrom light, the effectsof controlling optical
wavelengths, such as
cutting ultraviolet rays
(UV-A, UV-B) andshort wavelength blue
light (380 to 500nm)
from visible rays, havebeen raised. However, I do not believe that the effects ofimproving QOV (quality of vision) through optical
wavelength controlling and all of its possibilities havebeen adequately expressed.

When considering QOV, it may also be necessary totake into account not just the vision (sensitivity andresolving power of eyes) of theFigure 1observer, but also wavelength control
Relationship between Appearance of Objects, Light Source,by light source (illumination) and by
and Perception of Observers
having a lens in front of the eyes
(Figure 1). When we look at objects,
Changing light source
Perception of observer
the object is illuminated by light(wavelength control of light source)(Wavelength control by lenses)
irradiated from the light source, andwe recognize the color and shape ofthe object by making incident thereflected light from the object on theeyes of the observer. If the wavelengthof the light source changes, theobject’ s appearance also changes.
Similarly, if the wavelength iscontrolled by a lens in front of theeyes, the object’ s appearance changes.

Reflection of object

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However, the light environment in our everyday lives isdiverse and cannot be adjusted in many cases. However,given that optical wavelength control by lenses (achieving a variety of spectral characteristics by adding coloringmatter) can be easily adjusted by putting on and taking
off glasses, this is a more practical solution. Lenses thatcut short wavelengths (blue light) to lighten photophobia
and protect eyes have mainly been used by low-visionpatients in the past. NeoContrast™ (Mitsui Chemicals,Inc. ) has been developed in recent years as a technique tocontrol optical wavelengths by selectively cutting yellowlight (approx. 585nm) (Figure 2). Correcting vision by
regular eyesight testing at everyday clinical practices isfine, however, middle and old-age symptoms such as“cannot see characters clearly” and “vision is hazy” areexperienced. This could be attributed to various causes,
but the effects of changing optical characteristics (yellowlight) that accompanies the aging process is seen as themain one.

Transmittance (%)

Figure 2

Funamentally, there is a slight yellowing of the crystalline lens from a young age rather than it becoming completely colorless and transparent1). With accompanimentof the aging process, there is a yellowing of the crystalline
lens and the permeation of the short-wavelength region(blue system) of visible rays of light worsens. The yellowing of the crystalline lens slowly advances as a personages, so while sense of color adapts and there is no clear
awareness of this, the medium and long wavelength
region (yellow system) is more pronounced and the fieldof vision has a yellowish tinge. Due to this, there is anawareness of reduced QOV due to reduced ability to
distinguish between subtle colors (e.g. black and navyblue). Sakamoto2) reported that cutting yellow light was
effective in improving contrast sensitivity of middle-aged
and older people. NeoContrast™ selectively cuts yellowlight (approx. 585nm) from the medium and long wavelength region that becomes more pronounced as people
get older, so one could surmise that it could improve

Light Transmittance of NeoContrast™ (Mitsui Chemicals, Inc.)
10090807060
50403020
100350450550650750

Wavelength (nm)Light Transmittance of NeoContrast™ is shown in the left diagram and an example of NeoContrast™ lenses (sportsglasses type) in the right photograph.

Contrast sensitivity testing
Spatial frequency (cycle/degree)

Figure 3

CSV-1000 (VectoVison)

361218High

Contrast (%)

Low

The left diagram shows the appearance of thecontrast sensitivity testing instrument(CSV-1000 by Vector Vision).
The right diagram shows the contrast
sensitivity testing target (striped target) usedby the CSV-1000. The target is set so that the
spatial frequency of its striped patternincreases the lower you go, and the contrast
reduces the further right you go.
The contrast sensitivity target is divided into a
top and bottom with a striped target on one
side and a monochrome target on the other.
The subjects answer whether the stripedtarget is top or bottom, and contrast sensitivity is obtained from the value of the contrast
sensitivity target with the lowest correct
answers.

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Contrast sensitivity testing results for the healthy
subjects while wearing and not wearing NeoContrast™
are shown in Figure 4. Contrast sensitivity while wearing NeoContrast™ is significantly high for 12cpd and18cpd (Mann-Whitney Rank Sum Test, p<0.05) compared to while not wearing it. Contrast sensitivity testing
results for the cataract patients while wearing and notwearing NeoContrast™ are shown in Figure 5. Contrast
sensitivity while wearing NeoContrast™ is significantly
high for all spatial frequencies (Mann-Whitney Rank
Sum Test, p<0.05) compared to while not wearing it. It
is necessary to infer the influence in the information
processing process of the color in the geniculate body andcerebral cortex from the retina’s cone cell (S cone, Mcone and L cone) as a reason for the contrast improvement effect due to wearing NeoContrast™. Reduced
sensitivity of S, M and L cones accompanied by the aging
process has been measured from a psychophysicalperspective, and it has been reported that sensitivity
decreases together with aging for all cone cells 3). The
influence of changes to crystalline lens optical character-Figure 4
Contrast sensitivity of healthy subjects
2.5

Contrast sensitivity (logarithm)

The most typical method of evaluating QOV is eyesighttests (using clear and high contrast light and shade visualtargets), but there is a contrast sensitivity test of “sense ofform (form perception)” for eyesight, which is difficult toassess. To test the QOV improvement effects of NeoContrast™, we measured contrast sensitivity using acontrast sensitivity testing instrument (CSV-100 madeby VectorVision) on a sample of 15 healthy subjects(average age of 36±6.9 years; corrected vision of 1.0 ormore) and 15 cataract patients (average age of 76 ±7.5
years; corrected vision of 0.3 to 0.7) (Figure 3). This
instrument quantitatively evaluates the contrast sensitivity thresholds of four spatial frequencies (A:3cycles/degree (cpd), B:6cpd, C:12cpd, D:18cpd). Whatever the
spatial frequency domain, if the contrast is high (large
difference between visual target and background), it iseasy to recognize, while characters with a low contrast(small difference between visual target and background)are difficult to recognize. If the contrast sensitivity value
is high, this indicates that the subject possesses an excellent sense of form and is able to recognize visual targets
with even small lightness and darkness differences(difference between eyesight target and its background).
The testing room illumination was set at 500lx.

istics becomes greater for the S cone, which possesses
spectral sensitivity in a particularly short wavelength
range. By selectively diminishing the medium and longwavelength range of approximately 585nm (yellow),
NeoContrast ™ relatively improves the perception ofblue light, which is an antagonistic color 4). Due to this,

2.0
1.5
1.0

While wearing NeoContrast™
Without lenses

0.50.0A (3c/d)

B (6c/d)C (12c/d)

D (18c/d)

Spatial frequency (cycle/degree)＊:Mann-Whitney Rank Sum Test, p<0.05
This shows contrast sensitivity while wearing NeoContrast™
and without lenses based on a sample of healthy subjects(average age of 36±6.9 years).
The vertical axis is contrast sensitivity vales (value calculated
from inverse of target contrast value (%) is converted to alogarithmic value (log)), which shows that the contrast
sensitivity is better the higher the value.

Figure 5Contrast sensitivity of cataract patients
2.5

Contrast sensitivity (logarithm)

QOV by compensating for the effects of a yellowing
crystalline lens that comes with aging.

2.0
1.5
1.0
0.5

While wearing NeoContrast™
Without lenses

0.0
A (3c/d)

B (6c/d)C (12c/d)

D (18c/d)

Spatial frequency (cycle/degree)＊:Mann-Whitney Rank Sum Test, p<0.05
This shows contrast sensitivity while wearing NeoContrast™
and without lenses based on a sample of cataract patients(average age of 76±7.5 years).

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the color perception balance of contrast sensitivity test
targets (Figure 3 left) improves (white becomes whiterand the difference between black and white becomesclear) and it can be inferred that there is a possibility that
this leads to improved contrast sensitivity results.
To securely maintain QOV in one’s everyday life, which
is subject to a changing light environment, there is apossibility that optical wavelength control with a lens canhelp to securely maintain QOV whether indoors oroutdoors. The NeoContrast ™ being introduced here
selectively cuts yellow light (approx. 585nm), so reading
printed letters in a newspaper under indoor lighting(daylight color: slightly yellow illumination light, color
temperature of 5000K) should become easier andoutdoor visibility should improve. Reduced visibility inurban areas due to air pollution is becoming a significant
problem, which is leading to even more serious problems
such as car and aircraft accidents. Figure 6 shows changes in visibility in urban areas by wearing NeoContrast ™.
It is recognized that wearing NeoContrast™ improves
visibility by reducing yellowing and improving contrasts.
Given that improving outdoor visibility directly helps toprevent car and aircraft accidents, there are hopes that
NeoContrast™ can be applied as a traffic safety measure.

Figure 6Changes in visibility in urban areas while wearing
NeoContrast™

This shows changing visibility by wearing NeoContrast™ inIndian urban areas (Mumbai: region with a relatively low levelof air pollution), which have a serious air pollution problem.
Through this lens, yellowing is reduced and contrast (particularly building contrasts) and color vividness is perceived
better.

Bibliography

With regard to the effects of wavelength control by spectacle lenses, it will be necessary in the future to once
again examine the wavelength region to be cut as well aslens strength (transmissivity), and to develop optical
wavelength effects that adapt to lifestyle situations andenvironments. The NeoContrast™ introduced herecould be called an innovative lens technology that is thefirst step to an optical wavelength control effect that canproduce an improved QOV effect through improved
contrast (visibility improvement).

1) Tanito M, OkunoT, Ishiba Y, Ohira A. Transmission spectrum
and retinal blue-light irradiance values of untinted andyellow-tinted intraocular lenses. J Cataract and Refract Surg,
36:299-307,2010.
2) Sakamoto Y. Shading and Visual Functions – Challenge toCreate Transparent Eye Goggles. Japanese Society for
Cataract Research, 22, 24-28, 2010. (in Japanese)
3) Sagawa K, Takahashi Y. Spectral luminous efficiency as afunction of age. J. Opt. Soc. AM. A, 18:2659-2667,2001.
4) Zeki S. The retinex theory and the organization of the colour
pathways in the brain. Vision of the Brain. Blackwell Scientific
Publication1993, p246-255.

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