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					Arthur Bradley, Ph.D. Indiana University School of Optometry
Colored
Filters



          The physics of filters can vary
          (absorption, reflection, interference), but
          the efects on vision are independent of
          the method by which the filter fails to
          transmit select spectral ranges.
100%


                                                       Absorbing
             Interference                              filters
             filter



                      Wavelength (nm)



       400                  500              600                   700
   violet     blue          green   yellow    orange       red

         Color names associated with monochromatic stimuli
     Applications of Colored Filters
             in Optometry
1. Cosmetic/Aesthetic Sunglasses
2. Cosmetic/Aesthetic Contact Lenses
3. Aids for “color blind” individuals
4. Therapy for Dyslexics
5. Vision Enhancers for visually normal
      (a) general usage
      (b) specific applications
6. Aids for Visually Disabled
1. Cosmetic-Aesthetic filters
Prescription and non-prescription “sunglasses”




 Possible hazard of colored filters: potential to
 alter important colors.
ANSI Standard Z80.3 2001                                          Non-
                                                                  prescription
                                                                  sunglasses
       CIE x/y color space
 0.9
                                                                  and fashion
                       Green Traffic
 0.8                   Signal                                     eyewear
 0.7                                                              requirements.
                                                     Yellow
 0.6
                                                     Traffic Signal
 0.5
                                                                       They must not
 0.4
                                                                       alter colors
 0.3
                                                                       too much.
 0.2
                                                                       Green must
 0.1
                                                                       still be green
   0
                                                                       and yellow
                                           x
       0   0.1   0.2     0.3         0.4
                               x coordinate
                                               0.5   0.6   0.7   0.8
                                                                       still yellow!
2. Cosmetic/Aesthetic Contact Lenses




                          Everything looks fine
                          from the line of sight, but
                          the CL pigmentation is
                          not in the same plane as
                          the iris pigmentation.

                          Consequences…..
 Off-axis
 Eccentric target
                                 Effect of tinted CLs
                                 on peripheral vision




Pigmentation in corneal plane lies directly in    Retinal image
the path of the rays that form peripheral
images. This reduces retinal illuminance for
peripheral targets and thus visual sensitivity.
Am J Optom Physiol Opt 1987 Jan;64(1):38-40 Visual field loss
with colored hydrogel lenses. Josephson JE, Caffery BE.
The visual fields of 10 healthy myopic patients were compared using
hydrogel lenses with a clear pupil and an opaque colored portion
covering the iris and clear hydrogel lenses. Significant (greater than
10 degrees) field loss was found in all cases when the
midperipherally colored lenses were worn.


Arch Ophthalmol 1988 Dec;106(12):1680-2 Visual field constriction
caused by colored contact lenses. Insler MS, Hendricks C, George
DM. Louisiana State University Medical Center School of Medicine,
Goldmann visual field testing was performed on ten patients while
they were wearing the recently released DuraSoft 3 colored soft
contact lenses. All patients but one had visual field constriction
ranging from 5 degrees to 20 degrees.
  3. Aids for “color blind” individuals

FDA Premarket Notification Devices (510(k)s clearances
1. K994320 for ChromaGen lenses, made by Cantor & Silver
Limited (Northants, England) were cleared for market by the FDA
on October 20, 2000.
* These are tinted prescription contact lenses intended as an optical
aid for people with red-green color vision deficiencies.
   * The lenses do not help wearers to see "new" colors or to
perceive or appreciate colors as people with normal color vision do,
but merely add brightness/darkness or hue differences to colors that
are otherwise difficult or impossible to distinguish.
 * ChromaGen lenses are not effective for people who are totally
color-blind, or who have yellow-blue deficiencies.

  Designed for MONOCULAR wear (least dominant eye).
  Work via inter-ocular brightness comparisons.
FDA continued:
* Although ChromaGen lenses are the first such
contact lenses to be cleared by the FDA for
commercial marketing in the United States, the
idea is far from new. The use of colored filters as
an optical aid for color deficiency has been
reported in the scientific literature since the
1850's. A red-tinted hard contact lens known as
the "X-Chrom" lens (a pre-amendment device)
has been used for decades, and the FDA recently
cleared filtered spectacle lenses for the same
intended use.
New Innovation specifically for driving and recognizing colors of
traffic signals.




Reflective coating
on front surface to
make red band
invisible


   Peli E, Keeney KL. Device and method of enhancing color
   discrimi-nation for red/green traffic lights for persons with color
   vision defi-ciencies. US Provisional Patent Application
   60,377,317. December 19, 2001.
Example of lenses taken from Dr. Peli’s Glenn Fry lecture article
in Optometry and Vision Science (a very good read!)




Note a red and
green traffic
light.
Notice that the red light appears
bright and the green dark.
A recently FDA approved Spectacle Lens for “Colorblind” individuals


                             “Color max Color Vision
                             Enhancement Lenses are the first
                             and only lenses clinically proven
                             to improve color vision
                             discrimination in colorblind
                             individuals. This unique
                             technology alters the spectral
                             energy composition of the retinal
                             stimulus and adjusts the
                             deficiencies of brightness, hue and
                             saturation to balance color vision.”

                               $5,000 to get the “test kit”.
                               $400 estimated per prescription.
                               Quote from Color Max literature
                                   1Optometrist.com was the first
                                   optometric practice in New
                                   England authorized to dispense
                                   ColorMax® products.

“More than a decade in development, these
groundbreaking new lenses have been clinically proven
to greatly improve color discrimination for 95 percent
of the patients who wear them.”
CNN article: When optometrist Frank Siciliano, O.D., first saw
an advertisement for ColorMax eyeglass lenses, he took more than
a professional interest. Siciliano, who runs the Belmont Eye
Clinic in Youngstown, Ohio, is colorblind himself and knows the
frustration of not being able to see the world in full, brilliant color.
"There is no question they work," he says. "They are like wearing
sunglasses, but they enhance reds. They brighten and lighten the
shades you now see as dark and washed out. And the problem
with greens is they aren't dark enough. With the lenses, the greens
are much darker and you can see contrasts."
 ColorMax lenses have a unique coating that "fine tunes" the light
entering the eyes, and colorblind people will be able to improve
their ability to perceive some colors. James Bailey, O.D., Ph.D., a
member of ColorMax's science advisory board and a faculty
member at the Southern California College of Optometry in
Fullerton, emphasizes that the new lens coating is not a cure for
colorblindness
After approving the Color Max lenses, the FDA received some
complaints (some from me) about the claims made by Color Max. In
response to these, they published an FDA Talk Paper

COLORMAX LENSES
The FDA has received a number of media inquiries about ColorMax eyeglass lenses, which
are being promoted widely as a way to correct color blindness. Some of the claims in these
promotions may be misleading.


ColorMax lenses, made by Color Vision Technologies, Inc., Tustin,
Calif., were cleared for market by FDA in November 1999. They are
tinted prescription spectacle lenses intended as an optical aid for
people with red-green color vision deficiencies. The lenses do not
help wearers perceive or appreciate colors as people with normal
color vision do, but merely add brightness/darkness differences to
colors that are otherwise difficult or impossible to distinguish.

However, discrimination of at least some other colors is actually
impaired.
ColorMax lenses are coated with colored filters using a
technology similar to that used to apply colored coatings
on prescription sunglasses. The coating process is not
new or "high-tech" as stated in some of the company's
promotional reports.

Although ColorMax lenses are the first such lenses to be
cleared by FDA for commercial marketing in the United
States, the idea is far from new. The use of colored filters
as an optical aid for color deficiency has been reported in
the scientific literature since the 1850's.


 By 2002 the Color Max Lens web site had disappeared.
The impact of pink/magenta




                                 Transmission
filters on color:
E.g. the X-Chrom lens (pink CL
worn monocularly)


                                                Wavelength


                                                Logic: (1) compress
                                                color, but along color-
                                                blind dimension
                                                producing no collapse of
                                                color space for
                                                dichromat, (2) exaggerate
                                                color along orange-blue
                                                dimension, (3) introduce
                                                intensity differences
Problems:

1. Pulfrich effect
2. Subjects can use intensity signals to pass
color vision screeners even though they still
cannot correctly name red or green colors.
3. Some bright green targets may now appear
identical to low intensity reds.

Never use Green filters because they make red
lights difficult to see, which is not such a good
idea.
4. Therapy for Dyslexics
 Irlen Syndrome was first identified by Educational Psychologist,
 Helen Irlen, while she was working with adult-learners in
 California in the early 1980s. She observed that some of her
 students read with greater ease when they covered a page of print
 with a Colored overlay. The patented treatment-method uses
 “specially formulated”, coloured overlays or colored lenses worn
 as glasses or contact lenses to reduce or eliminate perception-
 difficulties.




                             http://www.irlen.com/NoAm.htm
The Irlen syndrome, or the “Scotopic Sensitivity Syndrome”,
implemented perhaps the most innovative and yet most
controversial use of colored filters.
Although developed by a
psychologist (Helen Irlen),
this therapy has been
adopted by Eye Care
professionals in some
countries, e.g. the UK.
Although the Specific
Learning Disaility, or
Dyslexia appears to be a
cognitive disorder, there is
evidence to indicate that
the visual system might be
involved. Thus, it seems
natural for Optometry to
be involved in this
optically-based treatment
option.
 Four strategies to “color” the retinal image of text.
          Tinted
Colored                             Tinted
          Overlay          Tinted
Text                                  CL
                             SL




Colored
Text
Web-based marketing: “It is estimated that up to one person in ten
is dyslexic. If not attended to, the effects of dyslexia can be
devastating, often resulting in a huge loss of self-confidence. If you
answer 'Yes' to four or more of these questions, then your son or
daughter may be dyslexic:
• • Are there any family members who experienced difficulty learning
to read or spell when they were at school?
• • Has your child suffered from repeated ear infections?
• Is your child experiencing feelings of failure at school?
• Does your child have difficulties with spelling?
• Does your child confuse left and right?
• Is anyone in your family left-handed?
• Does your child find difficulty working with numbers?
• Does your child have difficulty reading aloud?
• Does your child get confused about following instructions, for
example when playing a game?
• Does your child have difficulty remembering the multiplication
tables?”                10 out of 10 children might meet these criteria
From: The world of misperception, Irlen Colored Filters
by Helen Irlen, M.A., M.F.C.C.

Seventy-five Irlen Clinics are located worldwide in the following
countries: United States, Canada, Republic of Ireland, England,
Iceland, New Zealand, Australia, Hong Kong, Jordan, South Africa,
and Belgium. Thousands of professionals in the United States have
been trained in the Irlen Method and are able to screen and identify
individuals with this type of perceptual problem. In addition, over
2,000 school districts in the U.S. use the Irlen Method to screen
children who are having academic difficulties and provide them
with colored paper for writing and colored overlays to use over
reading material.

email: IrlenInstitute@irlen.com
Ophthalmic Physiol Opt 1991 Jul;11(3):206-17 Tinted lenses and
related therapies for learning disabilities--a review. Evans BJ,
Drasdo N. Department of Vision Sciences, Aston University,
Birmingham, UK.
Research relating to the use of Irlen tinted lenses and coloured
overlays for underachievers is reviewed. Many of the studies
were not published in refereed journals and were
methodologically poor. The weaknesses of the Irlen argument
are discussed, including the absence of evidence to support the
claims that these tints need to be uniquely prescribed and
manufactured. …….. Owing to the poor quality of much of
this research the claims of the protagonists of these therapies
cannot be proved or disproved. A proposed new therapy is
normally preceded by a valid theoretical hypothesis; this has been
lacking in the present topic.
Good News for Optometry: The best research in this field is
carried out by Optometrists! The psychologists generally produce
very inferior research on this topic.
Example:
 Optom Vis Sci 1997 May;74(5):298-302 Irlen lenses do
 not improve accommodative accuracy at near.
 Ciuffreda KJ, Scheiman M, Ong E, Rosenfield M, Solan
 HA.

 SUNY State College of Optometry, Department of Vision
 Sciences, New York, USA.

       “The use of Irlen correction did not have any
       positive effect on monocular steady-state
       accommodation at near.”
5. Vision Enhancers for visually normal
                                              Wesley-Jessen has
                                              incorporated this lens
                                              color and
                                              transmission into its
                                              “ProSoft” CL

“The Bolle Competivision Tennis sunglasses have become the
official eyewear of the United States Professional Tennis
Association and has already won Tennis Week Magazines'
Golden Acorn Award for the best on-court product.

Bolle's patented Competivision lens is the most innovative sports
technology and is the first and only authentic tennis sunglass that
gives you 100% UVA and UVB protection, while allowing you to
see the ball better.”
Contrast Enhancement with colored lenses

                                     Yellow
                                      Tint



 With yellow filter, non-yellow
 stimuli will appear darker.
 In the case of yellow tennis ball
 on green grass, the grass will be
 darker and less green (more
 yellow). For yellow targets on a
 blue background (e.g. the sky),
 the increase in contrast can be
 dramatic.
                   Pro-Soft Transmission Curves

                        Pro-Soft.IU         Pro-soft.W-J         63-H
                                                                                    Transmission
 100
  90
                                                                                    characteristics
  80
  70
                                                                                    of the ProSoft
  60
  50
                                                                                    CL by Wesley-
  40
  30
                                                                                    Jessen
  20
  10
   0
       400   450        500           550        600       650          700   750
                                  Wavelength (nm)




       400             500                       600                    700
ProSoft and Competivision reduce luminance of tennis ball, but
reduce the luminance of a red (clay) court even more, producing
marked increase in bll/court contrast.
Design Problem: Tennis ball is seen in front of many backgrounds.
E.g.Cross-court serve
Design Problem: Tennis ball is seen in front of many backgrounds.
E.g.Cross-court serve
The Special Case of the Yellow Lens:




The world looks brighter through a yellow lens! Explanation
of this phenomenon is not known.

Because of the increased brightness, many claims have been
made that vision is improved by such yellow lenses (brighter is
surely better!!).
Why do things appear brighter through a yellow
lens?
1. Pupil spectral sensitivity curve is different from
the visual sentivity curve. Pupil is more sensitive to
shrt wavelengths. Thus, a yellow filter puts the
pupil in the dark, thus it dilartes and more light
actually reaches the retina.
2. Perceived brightness is created by both the
amount of light and the color. A yellow filter
reduces the amount of light very slightly, but add
significant color, thus the world looks brighter.
Do we see better with Yellow
Filters?

Simple answer is NO!

Predictably, yellow or achromatic
targets seen against a blue
background are more easily
detected.
6. Aids for Visually Disabled
Ophthalmic Physiol Opt 1990 Jul;10(3):219-24
Do long wavelength pass filters improve low vision performance?
Leat SJ, North RV, Bryson H. Laboratory of Experimental
Optometry, University of Wales College of Cardiff, UK.
It has been suggested that the wearing of band-pass tints may
improve the contrast performance in certain ocular conditions. We
examined this by measuring grating visual acuity (VA) for targets of
various contrasts. The benefits of Corning CPF 511, 527 and 550
lenses, and neutral density (ND) filters were examined with and
without the presence of glare. Generally, patients with anterior sector
conditions showed improved performance with band-pass filters (not
with ND filters). It is suggested that the filter reduces the scatter
within the ocular media. People with retinitis pigmentosa or diabetic
retinopathy rarely benefited. We suggest that a condition of glare is
incorporated when assessing suitability with tints.

				
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