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Coloured filters for reading: Do
they help?
Catherine Suttle
http://www.telegraph.co.uk/news/health/10340122/
Why-Johnny-Depp-and-I-see-the-world-through-
blue-tinted-spectacles.html
http://www.dailymail.co.uk/health/article-
1259447/Tom-Heaffey-The-boy-blue-tinted-
glasses-cured-Meares-Irlen-syndrome.html
https://ceriumvistech.com/
A bit of history:
■Olive Meares, 1980: Reported that some school
children experience distortions when reading, and
these are alleviated by coloured paper or overlays
■Helen Irlen later reported the same in adults
Meares-Irlen Syndrome
Also known as Visual Stress
■Pattern-related visual stress* at about 3 cycles per
degree
* e.g. pain,
movement,
wobble, colour,
shapes in text
The Irlen Institute
170 ‘Irlen diagnosticians’ (14 in UK)
Thousands of ‘Irlen screeners’
http://irlen.com/
https://www.torbayandsouthdevon.nhs.uk
http://www.s4clp.org/
https://www.colorimetryinstitute.org/
https://www.abc.net.au/news/2019-06-26/irlen-syndrome-
medical-eye-condition-controversy/11218184?pfmredir=sm
Irlen diagnosticians
may be invited into
schools to test
children and / or to
inform teachers
about Irlen syndrome
https://www.tes.com/news/myth-
coloured-overlays-help-dyslexic-pupils
https://www.newscientist.com/article/
dn27588-forget-colour-overlays-
dyslexia-is-not-a-vision-problem/
Probably very confusing for parents, teachers, children and adults
with visual stress…and optometrists!
Often defined using reading
speed.
Increase in reading speed of
5% to 25% have been used to
define visual stress, hence
variation in prevalence.
How prevalent is visual stress?
45% in dyslexic readers; 55%
in normal readers
32% in dyslexic readers; 22%
in normal readers
45% in dyslexic readers; 55%
in normal readers
32% in dyslexic readers; 22%
in normal readers
Reanalysis of these data with a
15% reading speed increase
suggest 20% in dyslexic readers
(Evans and Allen 2016).
Evans et al 2017
How is it diagnosed?
Full eye examination
Overlay colour choice
Precision tinted lens choice
Refractive/other error management
Use at home/work/school
How is it treated?
http://www.colorimetryinstitute.org/
Selection of coloured overlays
(above)
Use of the Intuitive Colorimeter to
select a precision tint.
What’s the rationale – why might colour help?
In migraine sufferers with symptoms of visual stress,
cortical excitation was reduced when viewing through a
chosen tint.
It was concluded that people with visual stress have
‘hyperexcitability’ of the visual cortex, and this is
reduced by light of specific colour.
Huang et al, 2011
Why might colour help?
In migraine sufferers with symptoms of visual stress,
cortical excitation was reduced when viewing through a
chosen tint.
It was concluded that people with visual stress have
‘hyperexcitability’ of the visual cortex, and this is
reduced by light of specific colour.
Huang et al, 2011
But…
in another study cortical activation
was increased in people with
visual stress viewing through their
chosen colour
Kim et al 2015
So we don’t yet know
What does research tell us about the benefits of
reading through colour?46 primary school children (who found
an overlay more comfortable for
reading) chose a coloured overlay on
two occasions 3 months apart.
Repeat3
months
Jeanes et al 1997
On average, overlays chosen 3 months
apart were separated by 0.076 units in
this colour space.
On average, overlays chosen 3 months
apart were separated by 0.076 units in
this colour space.
This could be the difference between rose
and grey, or rose and yellow, for example
After 10 months, some children were still using overlays.
Their reading speed was higher with the overlay than
without (p<0.05)
After 10 months, some children were still using overlays.
Their reading speed was higher with the overlay than
without (p<0.05)
This could be a placebo effect – the child knows whether he/she
is looking through colour and may behave accordingly.
Subjects were told the UV filter was a ‘wonderful discovery’ for
people with reading difficulty, to reduce any placebo effect
33 adults and children with visual
stress compared reading with
their chosen coloured overlay
versus a UV filter overlay
Vs
On average, reading
speed was 4% faster
with the chosen
coloured overlay than
with the UV filter
(p=0.002)
Could this be a placebo effect?
Optimal tint Placebo tint
68 children
Outcome
measures:
Reading speed
Diary of
symptoms
Subjects kept a daily
symptom diary. On average,
71% of days were symptom-
free when wearing the chosen
tint, and 66% of days were
symptom-free when wearing
the control tint (p=0.002).
Subjects kept a daily
symptom diary. On average,
71% of days were symptom-
free when wearing the chosen
tint, and 66% of days were
symptom-free when wearing
the control tint (p=0.002).
Of 36 people:
• 6 symptom free with either pair
• 11 less symptomatic with
placebo glasses
Reading Chosen tint Control tint Significance
Speed 9.37 9.22 NS
Accuracy 9.57 9.42 NS
Comprehension 10.28 10.12 NS
Neale Analysis of Reading: Any benefit of the chosen tint?
No difference in reading ability between
the chosen and placebo colour tint.
Systematic reviews on the efficacy of
colour for reading difficulty
Systematic reviews on the efficacy of
colour for reading difficulty
The reviewed research “did not show that the use of coloured filters led to
a clear improvement in reading ability in subjects with reading disability. It
was not possible to comment on whether coloured filters can improve
symptoms of visual stress that may be associated with reading disability
due to a lack of available evidence.”
Systematic reviews on the efficacy of
colour for reading difficulty
“… finding confirms earlier systematic reviews that
could not prove any positive effect of coloured lenses
on literacy achievement, and suggests that results are
mainly due to placebo effects”
Systematic reviews on the efficacy of
colour for reading difficulty
Despite limitations of research “the balance of
evidence suggests that coloured filters can alleviate
symptoms…The quality of evidence is less than
would be required for new surgical or medical
interventions, but coloured filters are a safer form of
intervention.”
Systematic reviews on the efficacy of
colour for reading difficulty
“…high or uncertain risk of bias … the use of coloured
overlays and lenses to ameliorate reading difficulties
cannot be endorsed … placebo, Hawthorne and novelty
effects provide the most likely explanation for the
benefit which many individuals report.”
None published a protocol.
Search, study selection, bias
assessment may be flawed in
some cases.
Overall, Albon et al (2008) and
Griffiths et al (2016) were good
quality reviews. Both concluded
that there is no reliable evidence
supporting efficacy of coloured
overlays or precision tinted
lenses.
Overview of systematic reviews
(Suttle et al, 2018)
We asked whether the colour needed for
relief of symptoms in visual stress:
1. Is repeatable
2. May be explained by the placebo effect
1: Repeatability of coloured overlays and
lenses in adults and children with visual
stress
Repeatability of coloured overlays and
lenses in adults and children with visual
stress
N = 21 (12 female)
Aged 8 to 55 years (mean 26 years)
2 to 57
days
(mean 25
days)
Results: Overlay colour repeatability
Category Two colour choices include:
Identical Identical colour or
combination
Similar At least one common colour
Different No common colours
Overlay 1 Overlay 2
Grey + Grey Grey + Grey
Grey + Grey Grey + Grey
Blue + Blue Blue + Blue
Aqua + Aqua Aqua + Aqua
Blue + Purple Blue + Purple
Aqua + Mint
Green
Aqua + Mint
Green
Aqua + Mint
Green
Aqua + Mint
Green
Overlay 1 Overlay 2
Aqua Aqua + Mint
Green
Lime Green +
Lime Green
Lime Green +
Mint Green
Lime Green Lime Green +
Mint Green
Overlay 1 Overlay 2
Purple Orange
Blue + Purple Aqua
Pink + Purple Orange
Blue + Blue Lime Green + Mint
Green
Purple + Blue Rose + Rose
Yellow + Yellow Orange
Rose Orange
Grey Orange
Same Similar Different
Yellow + Lime Green Rose
Yellow + Lime Green Purple + Pink
Rose Yellow
Results: Precision tinted lenses
■No-one chose an identical colour on the two occasions
■The second colour was always a different hue, and/or
more or less saturated
■This is not surprising, because the colours are specified
precisely
■So how different were they?
Lens tint differences chosen by subjects who chose the
same (left), similar (centre) or different overlay colours
Colour differences were much greater than a ‘just noticeable difference’
This is nothing new…
■Other studies have found similar levels of
repeatability, but have concluded that the colours
are similar (e.g. Wilkins et al 1994).
■But lack of overlay colour repeatability in half of the
patients diagnosed with visual stress raises
questions about the need for precise colour
specification.
2: A randomised controlled study on the efficacy of precision tinted
lenses for people with visual stress
Full eye examination
Overlay colour choice
Precision tinted lens choice:
Optimal and Placebo
Refractive/other error management
Use at home/work/school
Tint 1 one month
Tint 2 one month
Overlay two weeks
At each stage, reading
speed and subjective
rating of discomfort
level (scale of 1 – 10)
were recorded.
On completion, the
participant was asked
whether tint 1 or 2 was
preferred for reading.
Optimal and placebo
randomly allocated as tint
1 or two. Participants and
researchers masked to
allocation.
28 subjects – Reading rate similar with overlay, optimal and non-
optimal tint
Significantly slower with no colour (p<0.001), but similar with overlay or either tint (p=1.0).
Subjects’ comfort rating similar with optimal and non-
optimal tint
Discomfort significantly lower with any of the three colours (p<0.001) but similar
with the overlay or either tint (p=0.1).
About half of participants
(48%) preferred their
chosen precision tinted
lens.
The remainder (52%)
preferred the placebo or
expressed no preference.
Summary
■As yet, there is no clear evidence to support the use of
overlays or precision tinted lenses for reading difficulty.
■However, many patients find them beneficial.
■The benefit could be a placebo effect. Is there any potential
for harm?
■Harm could occur in the form of raised hopes, financial and
time expense.
References
• Albon et al (2008) The effectiveness and cost-effectiveness of coloured filters for reading disability: a
systematic review. University of Birmingham.
• Bouldoukian et al (2002) Randomised controlled trial of the effect of coloured overlays on the rate of
reading of people with specific learning difficulties. Ophthal Physiol Opt 22: 55-60.
• Evans et al (2017) A Delphi study to develop practical diagnostic guidelines for visual stress J Optom
10: 161-168.
• Evans and Allen (2016) A systematic review of controlled trials on visual stress using intuitive
overlays or the intuitive colorimeter. J Optom 9: 205-218.
• Galuschka et al (2014) Effectiveness of treatment approaches for children and adolescents with
reading disabilities: a meta-analysis of randomised controlled trials. PLoS One 9: e89900.
• Griffiths et al (2016) The effect of coloured overlays and lenses on reading: a systematic review of the
literature. Ophthalmic Physiol Opt 36: 519-544.
• Jeanes et al (1997) Prolonged use of colour overlays for classroom reading Br J Psychol 88: 531-
548.
• Suttle et al (2017) Coloured overlays and precision-tinted lenses: poor repeatability in a sample of
adults and children diagnosed with visual stress. Ophthalmic Physiol Opt 37: 542-548.
• Suttle et al (2018) Efficacy of coloured overlays and lenses for treating reading difficulty: an overview
of systematic reviews. Clin Exp Optom 101: 514-520.
• Wilkins et al (1994) Double-masked placebo-controlled trial of precision spectral filters in children who
use coloured overlays. Ophthal Physiol Opt 14: 365-370.
