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This study analyzed the effects of spectral overlays on ocular motility during reading among a clinical group of children and adolescents experiencing visual-perceptual distortions of text. We reviewed the records of 323 eye-hospital patients diagnosed with visual stress and divided this participant sample into two age-based cohorts: children (n = 184; Mean [M] age = 10.1, standard deviation [SD] = 1.3 years) and adolescents (n = 139; M age = 14.6, SD = 1.5 years). We used a Visagraph III Eye-Movement Recording System to record ocular motor efficiency while reading with and without spectral overlays, and we examined the following parameters: (a) Fixations, (b) Regressions, (c) Span of Recognition, (d) Reading Rate, (e) Relative Efficiency, and (f) Comprehension. Our results showed that using one or some combination of 10 participant-selected spectral overlays immediately and significantly (p < .001) reduced the number of Fixations and Regressions per 100 words, while there were significant (p < .001) gains in positive factors such as Span of Recognition, Reading Rate, Relative Efficiency, and Comprehension. Our findings indicate that spectral filtering can be an effective tool for helping many young patients who experience visual-perceptual distortions while reading. Future expanded research employing eye-tracking technology is clearly needed.
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Article
Spectral Overlays for
Reading Difficulties:
Oculomotor Function
and Reading Efficiency
Among Children and
Adolescents With
Visual Stress
Ma
´rcia Reis Guimar~
aes
1,2
,
Douglas de Ara
ujo Vilhena
1,2,3,4
,
Stephen J. Loew
2,5
, and
Ricardo Queiroz Guimar~
aes
1,2
Abstract
This study analyzed the effects of spectral overlays on ocular motility during reading
among a clinical group of children and adolescents experiencing visual–perceptual
distortions of text. We reviewed the records of 323 eye-hospital patients diagnosed
with visual stress and divided this participant sample into two age-based cohorts:
children (n¼184; Mean [M] age ¼10.1, standard deviation [SD]¼1.3 years) and
adolescents (n¼139; Mage ¼14.6, SD ¼1.5 years). We used a Visagraph III Eye-
Movement Recording System to record ocular motor efficiency while reading with
1
NeuroVision Department, Hospital de Olhos Dr. Ricardo Guimar~
aes, Nova Lima, Brazil
2
Laboratory of Applied Research in Neuroscience of Vision, Universidade Federal de Minas Gerais, Nova
Lima, Brazil
3
Graduate Program on Psychology: Cognition and Behavior, Department of Psychology, Universidade
Federal de Minas Gerais, Belo Horizonte, Brazil
4
Faculty of Psychology and Education Sciences, Universidade do Porto, Portugal
5
School of Psychology and Behavioural Science, University of New England, Armidale, Australia
Corresponding Author:
Douglas de Ara
ujo Vilhena, Laboratory of Applied Research in NeuroVision, Universidade Federal de
Minas Gerais, Rua da Paisagem, 220—Vila da Serra, Nova Lima, MG-CEP 30720-600, Brazil.
Email: douglasvilhena@ufmg.br
Perceptual and Motor Skills
0(0) 1–20
!The Author(s) 2019
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DOI: 10.1177/0031512519889772
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and without spectral overlays, and we examined the following parameters:
(a) Fixations, (b) Regressions, (c) Span of Recognition, (d) Reading Rate, (e)
Relative Efficiency, and (f) Comprehension. Our results showed that using one or
some combination of 10 participant-selected spectral overlays immediately and sig-
nificantly (p<.001) reduced the number of Fixations and Regressions per 100
words, while there were significant (p<.001) gains in positive factors such as
Span of Recognition, Reading Rate, Relative Efficiency, and Comprehension.
Our findings indicate that spectral filtering can be an effective tool for helping
many young patients who experience visual–perceptual distortions while reading.
Future expanded research employing eye-tracking technology is clearly needed.
Keywords
child motor development, eye-tracking analysis, ocular motor skills, perceptual dis-
orders, reading difficulties, spectral overlays, visual measurement, visual perception,
visual stress
Introduction
Reading is a challenging task, as it not only demands a complex cognitive net-
work to process reading content, but it also requires a refined coordination of
the eyes (and simultaneously compensating for head movements) in order to
efficiently track lines of text. Thus, a growing number of researchers have inves-
tigated reading difficulties beyond those that can be explained by socioeconomic
factors (e.g., poor education), neurocognitive anomalies (e.g., dyslexia), and
optometric or ophthalmological deficits (e.g., refractive errors and visual
acuity) (Gaertner et al., 2013; Nicolson & Fawcett, 2019; Stein, 2019;
Vidyasagar, 2019). As will be detailed here, many studies have reported that
the reading process can also be compromised by inadequate ocular motor skills
or neural-based visual processing anomalies (such as those present in patients
with Meares-Irlen syndrome or visual stress [VS]).
VS is characterized by visual discomfort when reading (e.g., sore or tired eyes,
headaches, photophobia, excessive blinking or squinting) and visual–perceptual
distortions of text (e.g., “halos” or “patterns” around words, or words appear-
ing to “move,” “vibrate,” or “shimmer”). VS symptoms are typically accompa-
nied by a clear and rapid deterioration in oral reading ability, usually occurring
within 5–10 minutes (Evans & Allen, 2016; Evans, Allen, & Wilkins, 2017; Loew
& Watson, 2013). Estimates of the incidence of VS in the general population
have ranged from 5% (Evans & Allen, 2016) to 24% (Jeanes et al., 1997), while a
number of studies have found significant symptoms of VS-related reading dis-
comfort in 12–14% of unselected samples of school and university students
2Perceptual and Motor Skills 0(0)
(Kriss & Evans, 2005; Loew, Marsh, & Watson, 2014; Loew et al., 2015).
However, the levels of VS severity appear to lie on a continuum from mild to
highly symptomatic (Evans & Allen, 2016; Evans & Joseph, 2002).
With respect to underlying biological factors, several studies have identified a
range of biochemical anomalies in people with VS, including abnormal metab-
olism of essential fatty acids (crucial for retinal and visual-pathway functioning;
Robinson, McGregor, Roberts, Dunstan, & Butt, 2001) and significant anom-
alies in urinary amino acids and blood lipids that may indicate immune system
activation (e.g., lower cholesterol levels, including low density lipoprotein [LDL]
cholesterol, and higher heptadecanoic acid levels; Sparkes, Robinson, Dunstan,
& Roberts, 2003). There is also a strong genetic predisposition to VS, as 80% of
VS-diagnosed children have one or both parents with similar symptoms
(Robinson, Foreman, & Dear, 1996, 2000). A higher prevalence of certain var-
iant alleles of the apolipoprotein-B100 gene (coding for a key cholesterol trans-
porter molecule) has also been identified in people with VS symptoms (Loew &
Watson, 2012).
It has been widely reported that VS symptoms can be alleviated by the use of
spectral overlays (colored plastic sheets) placed over a page of text when read-
ing. One variety of these translucent overlays is available from Irlen
International
TM
, and a set of these overlays contains a wide selection of
spectral-filtering colors ranging from those favoring shorter wavelength trans-
missions (e.g., “Aqua,” “Blue-Gray,” and “Turquoise” overlays) to those that
favor longer wavelength light (e.g., “Yellow,” “Goldenrod,” and “Peach” over-
lays). Many studies have reported positive reading effects through the use of
spectral overlays, including improvements in letter or number recognition and in
reading speed and accuracy (Allen, Evans, & Wilkins, 2012; Evans & Joseph,
2002; Kriss & Evans, 2005; Ludlow, Wilkins, & Heaton, 2006, 2008; Nichols,
McLeod, Holder, & McLeod, 2009; Noble, Orton, Irlen, & Robinson, 2004;
Singleton & Henderson, 2007; Wilkins, Lewis, Smith, Rowland, & Tweedie,
2001; Wright, Wilkins, & Zoukos, 2007). A recent study involving Brazilian
elementary school children also found that those presenting with several symp-
toms of reading discomfort were three times more likely (odds ratio ¼3.36) to
experience increased reading speed with spectral filters compared with readers in
a group of children with fewer symptoms (Garcia, Momensohn-Santos, &
Vilhena, 2017). Longitudinal studies have produced analogous results, for exam-
ple, Jeanes et al. (1997) and Wilkins et al. (2001) respectively found that 24%
and 31% of unselected children who volunteered to select an overlay of their
preference continued to read with it eight and 10 months later; thus, novelty or
placebo effects were unlikely to have been primary motivational factors. Noble
et al. (2004) found that reading with overlays helped VS-diagnosed children with
school-documented delayed reading reach expected grade-level reading norms
within three months, while a control group comprising similar children showed
negligible gains.
Guimar~
aes et al. 3
While the use of spectral filters has remained controversial, with some
researchers arguing that no benefits to reading by means of such tools have
been validated through scientifically objective measures (Griffiths, Taylor,
Henderson, & Barrett, 2016; Hyatt, Stephenson, & Carter, 2009; Ritchie,
Della Sala, & McIntosh, 2011, 2012), recent studies employing highly objective
measures (e.g., functional Magnetic Resonance Imaging) have detected hyper-
excitability of the visual cortex in research participants with VS, epilepsy, or
migraines and have produced evidence of marked reductions in excitation when
participants read while using self-selected colored filters (Chouinard, Zhou,
Hrybouski, Kim, & Cummine, 2012; Huang et al., 2011; Kim, Seo, Ha, &
Kim, 2015; Wilkins, Huang, & Cao, 2007). As strong criticisms of spectral
filter use persist, this study hypothesized that eye-tracking technology might
provide a novel, parallel means of objectively testing the validity of reported
benefits of spectral filters for people with VS by providing measurable physical
evidence of any changes or absence of changes in ocular motor skills.
Currently, the two most widely accepted neurological explanations of VS
(and spectral overlays as an assistive tool for VS) are the Cortical
Hyperexcitability and the Transient-on-Sustained Inhibition (ToSI) theories.
The former argues that visual distortions while reading are caused by hyper-
excited or abnormal neuronal firing in the visual cortex due to inadequate sen-
sorial excitation diffusion. Spectral overlays then might allow a greater diffusion
or distribution of reading information to less excited areas (Allen, Gilchrist, &
Hollis, 2008; Wilkins et al., 2001). This theory has been supported by the
reported benefits of spectral filtering for other conditions associated with corti-
cal hyperexcitability such as autism spectrum disorders (Ludlow, Taylor-
Whiffen, & Wilkins, 2012; Ludlow & Wilkins, 2016; Whitaker, Jones,
Wilkins, & Roberson, 2016), migraine headaches (Evans et al., 1999), photosen-
sitive epilepsy (Wilkins et al., 1999), and stroke (Beasley & Davies, 2013).
Alternatively, the ToSI theory concerns the relationship between the sus-
tained visual system (SVS) and the transient visual system (TVS), two parallel
spatiotemporal divisions of the neuro-visual network that simultaneously pro-
cess visual information transmitted via the parvocellular and magnocellular
retino-geniculo-cortical pathways, respectively (Pammer & Wheatley, 2001;
Stein & Walsh, 1997). The SVS primarily responds to low temporal and high
spatial frequencies (important for color and fine spatial details), while the TVS is
sensitive to high temporal and low spatial frequencies, and its high-velocity
conduction of neural signals is believed to be crucial for inhibiting (masking)
prior SVS-transmitted images formed from visual data received in immediately
preceding saccades (hence the term ToSI). Accordingly, highly efficient magno-
cellular pathway processing is essential for optimal functioning of the TVS and
is also crucial in controlling saccades, fixations, binocular coordination, and
general ocular stability.
4Perceptual and Motor Skills 0(0)
To date, it appears that only two studies have analyzed spectral overlay
effects with an eye-tracking system. Solan, Ficarra, Brannan, and Rucker
(1998) investigated the effects of filters on ocular motor skills (using
Visagraph
TM
II equipment) among elementary school children with and without
reading disabilities. Despite using only three spectral filters (Lee Filters
TM
clear,
gray and blue), Solan et al. (1998) found that 75% of the reading-impaired
participants demonstrated an increased reading rate and a decreased number
of fixations and regressions when using the blue filter to the point that earlier
statistical differences between the reading-impaired and control groups on these
variables disappeared. More recently, Razuk et al. (2018) found that a group of
18 dyslexic children showed reduced eye-fixation durations when reading with a
“green” versus a “yellow” filter (p<.02) and versus no filter (p<.05). For the
age-matched control group without dyslexia, there were no differences in mean
fixation durations between any filter conditions.
Although these prior studies shed light on improved ocular motor skills from
the use of colored filters when reading, they did not use a wide variety of spectral
overlays (with broad-ranging transmission specificities) and may not have
obtained optimal or comprehensive results. Moreover, participants in both stud-
ies were children with reading disabilities who may or may not have had VS that
is presumed to be the basis for needing spectral filters. Thus, this study used
state-of-the-art eye-tracking technology (Visagraph
TM
III equipment) to
observe the effects of VS child and adolescent participants’ self-selected overlays
(from a set of 10 colors) on their reading-related ocular motor skills.
Method
Participants
We performed this study at the NeuroVision Department of the Hospital de Olhos
de Minas Gerais, which mainly attends to patients with vision-related learning
problems. We reviewed records of all patients (n¼883) assessed from June 2007
to April 2015 in relation to ophthalmic variables (including visual acuity [far and
near], high-order aberrations, phorias, stereopsis, color vision, contrast sensitivity,
and visual field). All of these patients underwent assessments for the presence of
VS symptoms (including patient responses to spectral overlays) and, for all
patients, eye-movement data were recorded while reading. From this large data
pool, we identified patients who met the following five criteria: (a) self-reported
“visual distortions while reading” and “reduced distortions when viewing text
through an overlay,” (b) clinical ophthalmologist affirmation of their VS symp-
tomatology, (c) good binocular visual acuity (better than 20/20 Snellen Chart)
and normal color vision (Pseudoisochromatic Ishihara 25 Plates Test and
Farnsworth D15 Dichotomous Test), (d) a score of at least 70% on a
Comprehension Test, and (e) no extreme anomalies in their eye-tracking
Guimar~
aes et al. 5
recordings (we applied the Outlier Labeling Rule [with a g-value of 2.2] and found
that eye-tracking data from 22 of the 883 patients were extreme). It was crucial to
apply these criteria in order to separate those patients who could be definitively
categorized as having VS morbidity from those who may have other disorders
that can affect reading ability, as a common flaw of many prior studies of overlay
effects has been the use of cohorts with general reading disabilities, creating a
participant sample bias, as spectral filters are presumed to mainly benefit people
with VS (Evans & Allen, 2016).
The final “VS Group” consisted of 323 VS-diagnosed patients who met all of
the above criteria. We then divided this sample into two age-related subgroups:
children (n¼184; age range ¼8–12; Mage ¼10.1, SD ¼1.3 years; 67% male)
and adolescents (n¼139; age range ¼13–17; M
age
¼14.6, SD ¼1.5 years; 63%
male), as age can affect the scale of any intervention-related changes in reading
skills. The expected grade norms calculated for participants (according to the
Visagraph III Test-Manual: Taylor Associates, 2006) indicated that mean group
values closely corresponded to the reading performances of 5th-grade children
and 10th-grade adolescents.
When first seen, all participants’ parents or legal guardians consented (and
participants assented) to participate in a future study. The study was conducted
in accordance with the Declaration of Helsinki (2008).
Instruments
We assessed VS symptom levels with the Irlen Reading Perceptual Scale (IRPS;
Irlen, 2003), a tool that challenges patients with various visually stressing images
and tasks (e.g., counting how many lines or symbols are in an image). The IRPS
is designed to increase visual discomfort in order to quickly identify VS symp-
toms. After assessing baseline visual discomfort levels with the IRPS, the
10 Irlen Overlays were individually presented to participants in the same
order (Gray, Blue-Gray, Turquoise, Aqua, Green, Peach, Rose, Goldenrod,
Yellow, and Purple) and were placed over a page of a text written in Dutch
(meaningless to the patient). Participants were then asked to assess whether each
overlay improved or worsened their visual comfort and the image quality, until
they eventually selected an overlay (or two-overlay combination) that they felt
gave the most reading comfort.
Participants were also given the option of choosing no overlay at all; however,
among the initial 883 patients, only 14 (2%) did so. This small group did not take
part in the comparisons of reading eye movements with and without an overlay
and were not included in the VS group. Following each participant’s selection of
their preferred overlay(s), we presented them with 11 images illustrating possible
visual distortions while reading in order to verify whether they felt such symptoms
were minimized when viewed through their selected overlays.
6Perceptual and Motor Skills 0(0)
As noted, participants’ ocular motor skills were measured using a Visagraph
III Eye-Movement Recording System (Taylor Associates, New York).
This system uses lens-free goggles with inbuilt infrared sensors to record eye
movements during reading. As these goggles are worn by the participant, the
goggles automatically compensate for any small movements of the head or
body. The following oculomotor and reading parameters were measured and
analyzed: (a) Fixations: number of eye pauses (stationary periods) in a reading
from left to right per 100 words, (b) Regressions: number of times eye move-
ments are directed from right to left per 100 words, (c) Span of Recognition:
number of words read divided by the number of fixations, (d) Reading Rate
(with comprehension): number of words read in 1 minute without rereading, (e)
Relative Efficiency: reading rate divided by fixations and regressions, and (f)
Comprehension: percentage of correct answers in a questionnaire concerning the
content of the text that was read (10 yes or no questions).
Procedure
We administered the Visagraph III eye-tracking examination after the partic-
ipants self-selected their most preferred overlay(s). We adjusted the eye-
movement recording system to each participant’s interpupillary distance,
taking into account any refractive corrections. All participants were provided
with a text appropriate for their reading level and cognitive capacity in order to
minimize abnormal reading eye movements and allow a continuous reading
performance to be recorded. Participants read the texts aloud, first without an
overlay (baseline) and then with their chosen overlay(s).
The order in which the two tests were given remained consistent for all
participants, as there is prior broad research agreement that marked deteriora-
tions in the reading skills of individuals with VS usually occur within a
few minutes and would be expected to occur during the second reading test.
Thus, a key premise underlying this aspect of the study design was that any
results inferring improvements in eye-movement reading efficiency while using
the overlays would (in theory) be manifested on the second, rather than the first,
of the two reading tests. All texts were read from a viewing distance of 40 to
45 cm, and under standard office lighting (two-tube cool-white fluorescent lamp
ceiling-fixtures; 20 W 60 cm-tubes; correlated color temperature: 5,000 K; 120 Hz
flicker cycle).
The reading material consisted of a single paragraph of black text, printed on
a white paper, in Times New Roman font size 18 (we used a larger font to
highlight any reading-fluency problems that might be attributable to an inade-
quate Span of Recognition). The paragraph was 11.5 cm wide and made up of
10 lines (approximately 7 words in each); however, data from the first and last
lines were excluded from the analysis. After each reading, participants answered
Guimar~
aes et al. 7
10 questions about the text, permitting us to evaluate whether reading compre-
hension was good.
Statistical analysis
We used IBM SPSS Statistics (version 21.0, Chicago, IL) for all data analyses.
As Pearson bivariate correlations were above 0.97, the average values of eye-
movement data for the right and left eyes were calculated in relation to
Fixations, Regressions, and Span of Recognition.
To check for gender and age differences in the effects of spectral overlays
interventions on the VS patients’ eye movements and reading performance, we
conducted a series of two-factor split-plot analyses of variance (ANOVAs), with
Fadjusted as per the Greenhouse–Geisser method. The between-group variable
was gender group (girls vs. boys) or age-group (children vs. adolescents), and
the within-group variable was the reading condition (without overlay vs.
with overlay).
To establish the clinical significance of any group differences, we calculated
Cohen’s dto determine the effect size and interpreted results using Cohen’s
(1988) criteria of 0.2 for a small effect, 0.5 for a medium effect, and 0.8 for a
large effect. Pearson bivariate correlations were used in all sample comparisons,
effectively merging the ocular motor skills parameters with the two conditions
(“with” and “without” spectral overlays). Accordingly, we considered a pvalue
of less than .05 to be statistically significant.
Results
In this study, participants’ preferred-overlay selections ranged across all 10 of
the overlays presented (including 35 combinations), with the most frequently
chosen colors being “Purple,” “Gray,” and “Turquoise.” The results for each
parameter measured by the Visagraph III (with and without spectral overlays)
are shown in Table 1, and split-plot ANOVA analyses (Group Condition) are
illustrated in Figure 1.
With respect to any changes in the reading efficiency parameters when mea-
sured during the intervention condition (spectral overlays), there were statisti-
cally significant improvements across all six measures, with small-to-moderate
effect sizes found in each of these analyses (Table 1). When using spectral over-
lays, the children’s number of Fixations immediately decreased by 21%
(p<.001, d¼0.50) and the adolescents’ Fixations decreased by 13% (p<.001,
d¼0 .27). Likewise, Regressions were reduced by 26% (p<.001, d¼0.45) and
19% (p<.001, d¼0.26), respectively. Reading with overlays was significantly
improved on the other parameters as well. Span of Recognition (the amount of
information captured in each eye fixation) improved by 24% (p<.001, d¼0.51)
and 18% (p<.001, d¼0.40) for the children and adolescents, respectively.
8Perceptual and Motor Skills 0(0)
Table 1. Ocular Motor Skills, Without and With Spectral Overlays (Means), Intervention Differences (D), and Interaction Statistics (Groups
or Conditions).
Parameters
Children (n¼184) Adolescents (n¼139)
Interaction statistics
(Group Condition)
Without overlay With overlay
D(%) Pd
Without overlay With overlay
D(%) pd
F(1,
321) pMean SD Mean SD Mean SD Mean SD
Fixations 163.6 75.3 129.6 61.1 –20.8 <.001 0.50 135.7 63.8 118.2 64.3 –12.9 <.001 0.27 11.4 .0008
Regressions 42.9 28.1 31.6 21.5 –26.3 <.001 0.45 31.5 22.2 25.6 22.6 –18.7 <.001 0.26 8.15 .0046
Span Recognition 0.75 0.33 0.93 0.38 24.0 <.001 0.51 0.89 0.36 1.05 0.43 18.0 <.001 0.40 0.46 .4975
Reading Rate 167.7 83.1 214.9 94.0 28.1 <.001 0.53 212.8 86.9 255.6 107.1 20.1 <.001 0.44 0.40 .5265
Relative Efficiency 1.21 1.26 1.93 1.57 59.5 <.001 0.51 1.81 1.39 2.67 2.01 47.5 <.001 0.50 1.18 .2777
Comprehension 87.2 10.8 92.3 8.7 5.8 <.001 0.52 85.8 10.5 90.7 9.7 5.7 <.001 0.48 .003 .9582
Note. SD ¼standard deviation; D¼difference between conditions (Without and With overlays); p¼statistical significance; d¼effect size.
9
Figure 1. Split-plot analysis of the interaction effects of spectral overlays on Visagraph III Eye-
Movement Recording System parameters. (a) Fixations, (b) Regressions, (c) Span of
Recognition, (d) Reading rate, (e) Relative Efficiency and (f) Comprehension. Legend: gray
line ¼children; black line ¼adolescents.
10 Perceptual and Motor Skills 0(0)
Reading Rate was 28% faster for the children (p<.001, d¼0.53) and 20%
faster for the adolescents (p<.001, d¼0.44), with the two groups able to read
43 and 47 additional words per minute. Relative Efficiency improved by 60%
among the children (p<.001, d¼0.51), and 48% among the adolescents
(p<.001, d¼0.50). In addition, Text Comprehension also significantly
improved when reading with spectral overlays in both age groups (p<.001,
d¼0.52 and p<.001, d¼0.48), with the sample as a whole scoring 92% on a
comprehension test following each participant’s reading of a text in the overlay
condition compared with 87% after reading an equivalent text without spectral
overlays.
Split-plot analyses (see Table 1) revealed a statistically significant interaction
between Age Groups and Conditions (without and with overlays) regarding
Fixations, F(1, 321) ¼11.4, p¼.0008, and Regressions, F(1, 321) ¼8.15,
p¼.0046. No significant interactions were observed in relation to the other
parameters (Table 1). Post hoc analyses of these interactions showed that the
reductions in the number of Fixations, and Regressions, were significantly more
pronounced among children compared with adolescents (Figure 1). In other
words, children’s ocular motor skills appear to show greater immediate
improvements using spectral overlays in comparison to adolescent readers.
We found significant gender-related eye-tracking differences (with post hoc
analyses favoring girls better reading-related eye movements), with small effect
sizes in relation to Fixations (p¼.013, d¼0.21), Span Recognition (p¼.0096,
d¼0.21), Reading Rate (p¼.0023, d¼0.25), and Relative Efficiency (p¼.012,
d¼0.21), but only a nonsignificant trend in Regressions (p¼.07, d¼.15) and no
significant Comprehension differences. The gender sample did not differ in rela-
tion to age, and split-plot analyses revealed no significant interaction between
gender and age.
As seen in Table 2, the number of Fixations were strongly positively corre-
lated with Regressions (r¼.90) and strongly negatively correlated with Span of
Recognition, Reading Rate, and Relative Efficiency (r¼–.88, –.80, and –.75,
respectively). Regressions were also negatively correlated with Span of
Recognition, Reading Rate, and Relative Efficiency (r¼–.77, –.66, and –.64,
Table 2. Pearson Correlations Between Eye-Movement Parameters.
Parameters 2 3 4 5
1. Fixations .90
**
–.88
**
–.80
**
–.75
**
2. Regressions –.77
**
–.66
**
–.64
**
3. Span of Recognition .92
**
.95
**
4. Reading Rate .95
**
5. Relative Efficiency 1.0
Note. **p<.0001.
Guimar~
aes et al. 11
respectively). It was also of note that increased Span of Recognition was very
strongly and positively correlated with increases in Reading Rate and Relative
Efficiency (r¼.92, .95).
Discussion
The eye-tracking data recorded in this study showed immediate and significant
improvements in six oculomotor and reading parameters when children and
adolescents with VS read using self-selected spectral overlays compared with
their baseline results. With overlays, there were statistically significant decreases
in the number of Fixations and Regressions, whereas there were significant
increases in Span of Recognition, Reading Rate, Relative Efficiency, and
Comprehension. All of these eye-movement changes represent improvements
for reading purposes. We observed more efficient eye movements from spectral
filters with regard to the number of Fixations (per 100 words), as these were
reduced by 21% for children and 13% for adolescents. Similarly, the use of
spectral overlays decreased the proportion of regressive saccades by 26%
among children and 19% among adolescents with VS in this study, reducing
time and effort in the reading process.
The Span of Recognition (breadth of text in words or letters perceived during
one fixation) averaged .75 of a word per fixation at baseline for the children, and
this value jumped by 24% to almost full word recognition (.93) per fixation
when children read using the spectral overlays intervention. A wider Span of
Recognition should also assist the short-term memory for processing and
manipulating larger amounts of information during each eye fixation.
We obtained similar improvements with adolescents who were able to visualize
in excess of one word (1.05) per fixation when using spectral overlays, an
increase of 18% from their baseline levels. This implies that the spectral inter-
vention increased both foveal and parafoveal visual information processing and
this, in turn, would likely assist in predirecting the ensuing saccade to the next
optimal fixation point and allow more fluent reading (Ashby, Yang, Evans, &
Rayner, 2012), as, in fact, evidenced by reductions in Fixations and Regressions
in both age groups.
With respect to Reading Rate, both children and adolescents read faster
during the intervention condition (averaging 28% and 20% more words per
minute, respectively). Such immediate and substantial improvements in reading
rates also suggest that spectral overlays can promote more fluent reading for
many young people with VS. The Relative Efficiency parameter provided a
means of further evaluating reading performance by using a single, reliable
value that integrates the three most important eye-movement variables:
Fixations, Regressions, and Reading Rate. Moderate gains in Relative
Efficiency (Cohen’s d¼0.51) for the children and (d¼0.50) for the adolescents
showed that both groups of patients with VS improved their reading
12 Perceptual and Motor Skills 0(0)
performances. Our results also showed that Comprehension was markedly
improved with the use of spectral overlays.
Comparatively, we found that the reductions in the number of Fixations and
Regressions with the use of overlays were significantly greater in children com-
pared with adolescents, although these differences might have been partly due to
younger children starting from a lower reading efficiency baseline. In addition,
our data seemed to confirm the higher incidence of reading disorders (and of
neurodevelopmental problems generally) that have been found for males versus
females (Quinn, 2018). Even with respect to reading-related eye movements, our
post hoc analyses revealed that girls significantly outperformed boys on most
measures that were responsive to the intervention (Fixations, Span Recognition,
Reading Rate, and Relative Efficiency).
The high number of eye-movement regressions observed in the VS group
(at baseline) may be indicative of a greater necessity in these individuals for
corrective eye movements to recheck words (or phonemes) that were not suffi-
ciently attended to initially (i.e., were “skipped over”). Alternatively, this eye-
movement characteristic may reflect a need to adjust vergence (simultaneous
pupil movements) to allow a clearer visualization or it may occur due to con-
fused interpretation of prior content that then requires rereading. In individuals
with VS, however, regressions usually trace to an inefficient tracking of the lines
of text (Loew & Watson, 2013; Loew et al., 2014). In a sample of 27 children
with reading difficulties, Solan et al. (1998) found that using spectral filters
reduced the regression rate for their total group by 34%, a value similar to
our finding of 26% reduction among child participants. Thus, our results, dem-
onstrating that colored filters can significantly improve left-to-right eye-move-
ment efficiency and enhance perceptual accuracy, concur with Solan et al.’s
(1998) findings and are also consistent with positive reports of spectral overlay
effects for readers with VS in studies using dependent measures other than
eye tracking (Evans & Joseph, 2002; Garcia et al., 2017; Kriss & Evans,
2005; Ludlow et al., 2006, 2008; Nichols et al., 2009; Singleton & Henderson,
2007; Wilkins, Jeanes, Pumfrey, & Laskier, 1996; Wilkins et al., 2001; Wright
et al., 2007).
Past research has shown that students with reading disorders demonstrate a
higher number of Fixations while reading compared with other students
(Okumura, Wakamiya, Suzuki, & Tamai, 2006; Solan et al., 1998), possibly
due, at least in some instances, to the presence of visual distortions that neces-
sitate increased comprehension effort. Neurobiologically, to generate clear and
acute text visualization, the TVS and SVS must be highly synchronized so that
the viewer can continually erase the image created from preceding eye fixations.
This visual inhibition process is also referred to as visual backward masking
(Solan et al., 1998; Williams, Breitmeyer, Lovegrove, & Gutierrez, 1991).
A slight delay in the TVS may lead to delayed masking (inhibition) of the pre-
vious image, allowing it to outlast the normal duration of stimuli received
Guimar~
aes et al. 13
from the SVS and creating an after-imaging effect (or “visual noise”) that may
then interfere with new detailed text perception. The superimposed older image
inputs might generate a smeared or over-lapping image, explaining many of the
visual distortions reported by patients with VS (e.g., “halos” surrounding
words).
As it is already known that proficient, versus less capable, readers require
fewer eye fixations (eye pauses) and regressions (backward eye movements) to
read an identical passage of text, and prior research has shown that spectral
filtering increases the efficiency of the magnocellular pathway (Ray, Fowler, &
Stein, 2005; Stromeyer, Chaparro, Tolias, & Kronauer, 1997) and TVS–SVS
synchronization (Croyle, 1998), eye-tracking technology for refined eye-
movement analysis is a very logical next step for acquiring highly objective
measures of reading efficiency within research to assess the reported benefits
of spectral filters for VS, especially as ocular motor skills are only weakly
influenced by voluntary control during reading (Chase, Ashourzadeh, Kelly,
Monfette, & Kinsey, 2003; Greatrex & Drasdo, 1995; Stein, 2019).
Among the limitations of this study (and others) is its failure to fully control
for placebo effects, as some participants might expect any overlays placed before
them to be helpful. In the future, researchers might provide one overlay at
random, in addition to a clear overlay, presented in counterbalanced order to
all participants. This would allow testing for differences between self-chosen and
randomly chosen overlays, as it would limit building expectations of benefits
(placebo effect). Our own research design would have been improved by com-
paring reading-related eye-movement differences among participants with both
self-chosen spectrally tinted overlay and a randomly assigned clear overlay.
In partial response to this limitation, our use of four (of six) parameters that
measured large involuntary micro eye movements meant that some of our
dependent measures were less vulnerable to a placebo effect than dependent
measures in other studies. Meanwhile, a number of separate studies, not using
eye-tracking systems, have shown that self-chosen overlays yield greater perfor-
mance gains in comparison to: (a) randomly selected color filters (Bouldoukian,
Wilkins, & Evans, 2002; Wilkins & Lewis, 1999), (b) complementary colors
(Jeanes et al., 1997), and (c) aesthetically preferred overlays (Ludlow et al.,
2008). However, future research in this area should include an experimental
condition involving reading with a clear spectral overlay. Our study had several
clear and significant strengths in that our participant sample was very large, we
excluded participants without professionally identified VS, and we required all
participants to have 70% comprehension and good visual acuity. Yet, general-
ization of these findings may be limited by the fact that there may be VS severity
differences between our VS participants, identified by ophthalmologists from
among eye hospital inpatients, and ophthalmologist-identified individuals with
VS from among an outpatient population. Further research might next replicate
this study with a broader outpatient sample of VS participants.
14 Perceptual and Motor Skills 0(0)
An important demonstration within this study was that eye-movement
recording systems are important tools in reading research. They provide objec-
tive data reflecting eye-movement reading activity that may either result from or
cause reading problems, perhaps depending on the nature of different reading
disorders. In what appears to be only the third eye-tracking study of the VS
disorder and related overlay intervention strategies, we demonstrated that spec-
tral filtering can be beneficial for some children and adolescents who are strug-
gling with unexplained reading difficulties. This study showed that using spectral
filters during reading significantly improved participants’ ocular motor skills
(e.g., fewer Fixations and Regressions) and reading rate, presumably alleviating
baseline levels of print and background distortions among a clinical sample of
participants with VS. We propose that such improvements may also free work-
ing memory to permit greater time and effort to be directed toward “the mean-
ing of what is being read.”
Acknowledgments
The authors wish to thank Nigel V. Marsh, PhD, Department of Psychology, James
Cook University, Singapore, for his valuable assistance and advice concerning statistical
analysis.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research,
authorship, and/or publication of this article.
Ethical Statement
The Research Ethics Committee of the Universidade Federal de Minas Gerais approved all
procedures in the study (approval no. 49765115.0.0000.5149), and the study was con-
ducted in full accordance with the Code of Ethics of the World Medical Association
(Declaration of Helsinki, 2008) for research involving human participants.
Funding
The author(s) disclosed receipt of the following financial support for the research, author-
ship, and/or publication of this article: This study was financed in part by the
Coordenac¸~
ao de Aperfeic¸oamento de Pessoal de N
ıvel Superior—Brasil (Capes)—
Finance Code 001.
ORCID iD
Douglas de Ara
ujo Vilhena https://orcid.org/0000-0003-2670-7963
Guimar~
aes et al. 15
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Author Biographies
Ma
´rcia Reis Guimar~
aes, MD, PhD, is an ophthalmologist and Eye Pathologyst,
head of the Neurovision Department at Minas Gerais Eye Hospital. She earned
a doctorate degree in Ophthalmology and Neurosciences at Universidade
Federal de Minas Gerais (UFMG), a Master’s Degree in Molecular Biology
at Universite
´Paris VI, and is Graduate in Medicine at UFMG. She has a
Fellowship in Eye Pathology at Hospices Civils de Strasbourg (France),
Moorfields Eye Hospital (England) and Armed Forces Institute of Pathology
(USA). Guimar~
aes’s key research interests focuses on visual neuroscience, func-
tional vision and visual-related reading disorders.
Douglas de Ara
ujo Vilhena, MSc, is a doctoral student in Neuropsychology in
the Department of Psychology at UFMG with part in the Faculty of Psychology
and Education Sciences at Universidade do Porto. He has a Master’s Degree in
Human Development at UFMG, and is a Graduate in Psychology at UFMG
with part at University of Leeds. Vilhena’s key research interests focuses on
reading difficulties and aims to develop psychometric tests to evaluate reading
ability. He was granted by the Coordenac¸ ~
ao de Aperfeic¸ oamento de Pessoal de
N
ıvel Superior.
Stephen J. Loew, PhD, is an associate researcher of reading difficulties in the
School of Psychology at the University of New England and a research partner
with the Laboratory of Applied Research in Neuroscience of Vision at the
Federal University of Minas Gerais. Loew’s key research interests include the
nature of Meares-Irlen/visual stress syndrome, the overlap of associated symp-
toms with ADHD and other learning disorders, and the effects of increasingly
brighter classroom lighting on present-day literacy rates and learning in general.
Ricardo Queiroz Guimar~
aes, MD, Ph.D., is an ophthalmologist and head of the
Minas Gerais Eye Hospital. He earned a doctorate degree in Ophthalmology
and medical degree at UFMG. He has a Fellowship in Hospices Civils
Strasbourg (France), Moorfields Eye Hospital (England), Hotel Dieu Paris
(France) and Georgetown University (USA). Guimar~
aes is an active lecture
and his key research interests focuses on visual neuroscience, functional vision
and visual-related reading disorders.
20 Perceptual and Motor Skills 0(0)
... Current research focusing on dyslexia intervention focuses mainly on text adaptation (e.g., appropriate font size, line spacing, font or background color) [Rivero-Contreras et al. 2021] and also using eye-tracking to evaluate the effect of font size and spacing between words [Masulli et al. 2018]. Another way to explore the intervention of dyslexia is the focus on oculomotor therapy, which aims at the effect of color filters on reading rate and ability [Guimarães et al. 2020]. The effect of colored filters on reading abilities using eye-tracking was also performed by Razuk et al. [2018]. ...
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... Dentre os diversos fatores sensoriais e orgânicos que podem prejudicar a aprendizagem, destaca-se neste artigo as dificuldades de aprendizagem relacionadas à visão (DARV). Os professores e os gestores educacionais, que possuem um papel importante próximo aos alunos e na gestão escolar, devem ter autonomia para rastrearem todos com problemas relacionados à saúde ocular (ex., perda da acuidade visual), assim como dificuldades funcionais da visão (ex., estresse visual associado à dificuldade de leitura, déficit magnocelular, distúrbios do processamento visual) (Guimarães et al., 2019;Vilhena et al., 2021). ...
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El objetivo de esta investigación fue presentar datos epidemiológicos poblacionales sobre las dificultades de aprendizaje relacionadas con la visión recogidos en el Programa Buen Comienzo. Participaron 458 estudiantes del tercer año de la Enseñanza Fundamental (8,6 ± 0,7 años; 51% niñas). En primer lugar, se realizó la formación de profesionales de Salud y Educación. Los resultados indicaron una proporción importante de participantes, a través del Cuestionario de Caracterización de Dificultades Visuales y de Aprendizaje, con dificultades en fotofobia, cansancio o dolor de cabeza, percepción de profundidad, deportes de pelota, cansancio en el automóvil, lectura, lectura en computadora, matemáticas, caligrafía, redacción de ensayos y al copiar. Los participantes sintomáticos (16%), todos con agudeza visual adecuada, fueron remetidos para evaluación con la Escala de Percepción Visual de Lectura del Método Irlen. De estos, 86% informó dificultad para leer y 75% incomodidad de lectura moderada a severa. Todos los participantes, excepto uno, informaron una mejora considerable en la calidad visual con al menos una overlay espectral, siendo los más frecuentes Purple, Yellow e Gray. Los participantes sintomáticos informaron reconocer un promedio de 3,6 de las once ilustraciones de distorsiones visuales en la lectura, siendo las más frecuentes Washout, Blurry, Shaky, ríos, Star Wars y Ondulado. Los datos epidemiológicos poblacionales recopilados en el Programa Buen Comienzo demuestran una relevante prevalencia de dificultades de aprendizaje relacionadas con la visión en estudiantes.
... Children's oculomotor patterns during reading have been understood for several years, and they are known to differ from those of adults (Guimarães et al., 2020;McConkie et al., 1991;Rayner, 1986;. For instance, when compared to adults, children starting to read make several saccades of smaller amplitude, show more eye fixations with longer durations, and exhibit frequent regressive saccades (leftward saccades made to re-fixate the word read). ...
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To our knowledge, there are no studies recording the reading eye movements of children born prematurely. We examined the oculomotor patterns during reading of 23 children born prematurely ( M age = 7.8, SD = 0.2 years) to compare them with those from two groups of children born at full-term who were matched for chronological age or reading age, respectively. We found the oculomotor reading pattern in children who were preterm to be similar to that of children who were full-term and matched for reading age; this shared pattern was characterized by longer duration of fixations, frequent prosaccades of smaller amplitude and several backward saccades. In contrast, when these two groups were compared to full-term children matched for chronological age, the latter group showed significantly shorter duration of fixations, less frequent saccades and larger amplitude prosaccades. Thus, the oculomotor pattern we observed in 7-year-old children who were either preterm or reading-delayed, relative to their age-matched peers, reflected delayed development of brain areas involved in reading-related eye movements.
... Frequentemente, pessoas com estresse visual manifestam sinais de agitação motora e demanda por interrupções e paradas para descanso durante leituras que durem mais de quinze minutos, dependendo das características do texto, o que aumenta as repercussões negativas em tarefas de estudo ou de trabalho que demandem atenção (Guimarães, 2011). Consequentemente, as dificuldades visuais podem levar à perda de compreensão, releituras, dificuldade de concentração e baixo-rendimento escolar (Lopes, 2017;Wilkins, 1994Guimarães et al., 2019). ...
Article
O presente estudo analítico controlado, prospectivo e com mascaramento duplo-cego, teve o objetivo de (1) verificar se adultos com estresse visual, avaliados por um rastreador ocular, quando comparados a um grupo controle, apresentam diferença nos movimentos oculares durante a leitura de textos e (2) prover fontes de evidências de validade da estrutura interna para o Questionário de Caracterização de Dificuldades Visuais e de Aprendizagem. Participaram adultos com estresse visual (GEV; n = 16) pareados com um grupo controle sem estresse visual (GC; n = 24). Para as análises do rastreador ocular com tecnologia de infravermelho, cada participante realizou a leitura de dezesseis textos, apresentados de forma randômica, tendo o GEV realizado 239 leituras e o GC 342 leituras. Para o estudo de validação do questionário, foram adicionados retrospectivamente os prontuários de 291 adultos atendidos consecutivamente. Os resultados mostraram diferenças significativas entre os GEV e o GC com relação a: Fixação, Regressão, Duração da Fixação, Ataque Direcional, Taxa de leitura, Eficiência de leitura, Correlação cruzada, Anomalias de Fixação e Anomalias Binoculares. Esses resultados demonstram que o GEV, quando comparado ao GC, apresentou uma oculomotricidade menos eficiente, com pior correlação cruzada e maior número de Anomalias Binoculares, o que evidencia movimentos em direções opostas e dificuldade na coordenação binocular. O Questionário mostrou-se adequado na análise fatorial, o que adiciona evidências de validade da estrutura interna. Esses achados reforçam que os leitores com estresse visual apresentavam dificuldades oculomotoras na leitura.
... O estresse visual (EV), também referido como síndrome de Irlen, é um tipo de distúrbio do processamento visual caracterizado especificamente pela presença de (1) distorções visuoperceptuais do texto e (2) desconforto visual progressivo durante a leitura (Evans, Allen & Wilkins, 2017;Guimarães, Vilhena, Loew & Guimarães, 2019;). Diferentes distorções visuais podem ocorrer durante a leitura de textos, como a presença de sombras, halos e padrões ao redor das letras, espaçamentos irregulares ao longo do texto e percepção de movimento, como letras se destacando do papel ou vibrando (Irlen & Lass, 1989;Stein & Walsh, 1997;Wilkins et al., 2001). ...
Article
Pessoas com estresse visual, síndrome de Irlen, utilizam as lâminas espectrais (spectral overlays) para reduzir as distorções visuais e prevenir o desconforto visual durante a leitura. Este estudo teve como objetivo realizar uma revisão integrativa de 1980 a 2008 sobre o efeito das lâminas espectrais nos parâmetros visuais e na habilidade de leitura, sintetizando os principais resultados de cada artigo. Foram incluídos 36 artigos, lidos na íntegra, que utilizaram as Irlen Overlays ou as Intuitive Overlays. A década de 1980 foi caracterizada pela criação das Irlen Overlays pela psicóloga Helen Irlen, assim como as primeiras pesquisas e dissertações. A década de 1990 foi marcada pela criação das Intuitive Overlays, do Rate of Reading Test (Teste de Taxa de Leitura) e por estudos científicos com maior rigor metodológico. A década de 2000 foi caracterizada pela consolidação dos estudos internacionais sobre o estresse visual e o efeito das lâminas espectrais, em especial na Inglaterra e na Austrália. Esta síntese das três primeiras décadas de pesquisa sobre o uso de overlays oferece um recorte temporal importante dos estudos que precedem o início das pesquisas no Brasil. O uso das lâminas espectrais demonstrou ter respaldo na literatura como um instrumento de intervenção eficiente para reduzir o estresse visual e melhorar a leitura. Espera-se contribuir com o resgate histórico dessas pesquisas para que os futuros estudos tenham delineamentos que reproduzam os estudos internacionais e que superem as inerentes limitações metodológicas. ABSTRACT People with visual stress, Irlen syndrome, use spectral overlays to reduce visual distortions and prevent visual discomfort while reading. This study aimed to carry out a integrative review from 1980 to 2008 on the effect of spectral overlays on visual parameters and reading ability, summarizing the main results of each article. Thirty-six articles were included, read in full, that used the Irlen Overlays or the Intuitive Overlays. The 1980s were characterized by the creation of the Irlen Overlays by psychologist Helen Irlen, as well as the initial researches and dissertations. The 1990s were marked by the creation of the Intuitive Overlays, the Rate of Reading Test and scientific studies with better methodological rigor. The 2000s were characterized by the consolidation of international studies on visual stress and the effect of overlays, especially in England and Australia. This summary of the first three decades of research on the use of overlays offers an important time frame of the studies that preceded the beginning of research in Brazil. The use of spectral overlays has support in the literature as an efficient intervention tool to reduce visual stress and improve reading. It is expected to contribute to the historical rescue of these researches so that future studies have designs that reproduce international studies and overcome inherent methodological limitations.
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The Rate of Reading Test was designed with spatial and psycholinguistic controls to identify people with visual stress. The study aimed to adapt this test to Portuguese, providing psychometric evidence. In Step 1, the agreement between six independent judges was verified regarding the degree of difficulty of short high-frequency words. In Step 2, the accuracy of the words was verified in 80 readers from the 2nd to the 5th grades of Elementary Education. In Step 3, the judges chose the final words for the test from among those without accuracy errors. There was agreement among the judges in the adaptation to Portuguese, composed of 15 words of high frequency, common nouns, singular, regular, short extension and balanced by gender. In Step 4, the test’s reliability was investigated in 108 students of the 3rd grade, of whom 90 participated in the retest. The Teste de Taxa de Leitura showed satisfactory evidence of content validity and reliability.
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Purpose: Consistent with association between photophobia and headache, growing evidence suggests an underlying causal relationship between light sensitivity and central pain. We investigated whether an intervention to regulate light sensitivity by filtering only wavelengths causing difficulties for the specific individual could alleviate headaches/migraines resulting from traumatic brain injury (TBI). Methods: Secondary data analysis of a clinical database including N = 392 military personnel (97% men, 3% women), ranging in age from 20 to 51 years, diagnosed with TBI, persistent headaches/migraines, and light sensitivity. The average elapsed time from TBI diagnosis to intervention was 3 years. Headache/migraine severity, frequency, medication use, and difficulties related to daily functioning were assessed pre and 4-12 weeks post-intervention with individualized spectral filters. Results: Monthly migraine frequency decreased significantly from an average of 14.8 to 1.9, with 74% reporting no migraines post-intervention. Prescription and over-the-counter medication use decreased by more than 70%. Individuals also reported significant improvement in light sensitivity, headaches/migraine severity, and physical and perceptual symptoms. Conclusions: Wearing individualized spectral filters was associated with symptom relief, increased subjective quality of reported health and well-being, and decreased objective medication use for TBI-related persistent headaches/migraines. These results support a suggested relationship between dysregulated light sensitivity and central regulation of pain.
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Visual perceptual distortions and physical discomfort that cause difficulties in reading are some of the characteristics of Irlen syndrome. This study examined if students with Irlen syndrome, assessed with different reading tasks, show differences in reading skills when compared to those without this condition. Participants were 110 fourth and fifth graders (mean age = 8.6 years), 55 with Irlen syndrome (ISG group)and 55 without this syndrome (control group). Researchers applied the Irlen Reading Perceptual Scale to evaluate the Irlen Syndrome and the PROLEC-R Test to assess reading processes. The results showed significant group differences in Word Reading, Pseudoword Reading, Punctuation Marks, Sentence, and Text Comprehension. Oral comprehension in the auditory modality was not significantly different, which would support the idea that Irlen syndrome seems to be related to visual sensory processes. In conclusion, participants with Irlen syndrome showed impaired reading processes that might affect overall visual comprehension but not oral reading comprehension.
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This study aimed to examine the effects of colored blue electronic and overlay filters on reading performance and eye movements of children with and without dyslexia. Children with and without dyslexia (15 in each group) were recruited as participants and seated on a chair, with their heads stabilized by a forehead and chin support. They read different texts shown on a 14-inch laptop screen with no filter, blue electronic filter, and blue overlay filter. Eye movements were recorded using an eye-tracking system (ETG 2.0 - SMI), and the total reading time duration, number and mean fixation duration, and number and duration of saccades were obtained. Children with dyslexia showed longer reading durations and higher numbers of both fixations and saccades. In addition, they read faster with the blue overlay filter compared with in the other conditions. Furthermore, the blue overlay filter reduced the fixation duration and increased the saccade duration. These results show that a blue overlay filter improves reading performance in children with dyslexia owing to changes in eye movement patterns.
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It is now evident that explanations of many developmental disorders need to include a network perspective. In earlier work, we proposed that developmental dyslexia (DD) is well-characterized in terms of impaired procedural learning within the language networks, with the cerebellum being the key structure involved. Here, we deepen the analysis to include the child's developmental process of constructing these networks. The "Delayed Neural Commitment (DNC)" framework proposes that, in addition to slower skill acquisition, dyslexic children take longer to build (and to rebuild) the neural networks that underpin the acquisition of reading. The framework provides an important link backwards in time to the development of executive function networks and the earlier development of networks for language and speech. It is consistent with many theories of dyslexia while providing fruitful suggestions for further research at the genetic, brain, cognitive and behavioral levels of explanation. It also has significant implications for assessment and teaching.
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Objective: To investigate the effects of spectral overlays on reading performance of Brazilian elementary school children. Methods: Sixty-eight children (aged 9-12 years) enrolled in the 5th and 6th grade were included in the study. The Rate of Reading Test (RRT - Brazilian Portuguese version) was used to evaluate reading speed and the Irlen Reading Perceptual Scale was used to allocate the sample according to reading difficulty/discomfort symptoms and to define the optimal spectral overlays. Results: A total of 13% of the children presented an improvement of at least 15% in reading speed with the use of spectral overlays. Pupils with severe reading difficulties tended to have more improvement in RRT with spectral overlays. Children with severe reading discomfort obtained the highest gains in RRT, with an average of 9.6% improvement with intervention, compared to a decrease of -8.2% in the control group. Participants with severe discomfort had an odds ratio of 3.36 to improve reading speed with intervention compared to the control group. Conclusion: The use of spectral overlays can improve reading performance, particularly in those children with severe visual discomfort.
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Males are more likely than females to be identified as having reading difficulties, but it is unclear if this is a result of sample ascertainment or identification bias. The purpose of this meta-analysis was to determine the magnitude of gender differences in reading difficulties using available studies in which researchers investigated this difference and an additional dataset with a representative U.S. Sample: After conducting a literature search, sixteen studies and a restricted use dataset were included in the present analysis (N = 552,729). A random-effects odds ratio (OR) model indicated that males are 1.83 times more likely than females to have reading difficulties. Moderator analyses revealed that the gender ratio is greater when the identified reading difficulties were more severe. Further, this difference in identification rates across males and females was found without evidence of publication bias. Implications for the identification of students with reading difficulties are discussed.
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Purpose: Visual stress (VS) is characterised by symptoms of visual perceptual distortions and eyestrain when viewing text, symptoms that are alleviated by individually prescribed coloured filters. A recent review supports the existence of VS and its treatment, but noted that controversy remains, in part due to inconsistencies in the diagnosis of the condition. The present paper reviews the diagnostic criteria for VS in the literature and reports a Delphi analysis of the criteria currently used in clinical practice. Methods: Twenty-six eyecare practitioners were invited to participate in a Delphi study. They were selected because they were frequent prescribers of precision tinted lenses. In the first round they were sent a list of the indicators for which there is literature to suggest a relevance in the diagnosis of VS. The practitioners were invited to rank the indicators and add any additional criteria they use in diagnosis. In the second round a revised list was circulated, including items added from the responses in the first round. Results: The respondents included optometrists, orthoptists and opticians. In the first round the response rate was 85%. Ninety-one percent of those who participated in the first round also responded in the second round. Strong indicators in the second round included the symptom of words moving when reading, voluntary use of an overlay for a prolonged period, improved performance of ≥15% with an overlay on the Wilkins Rate of Reading test, and an abnormally high score on the Pattern Glare Test. Conclusions: The strongest diagnostic criteria are combined in a diagnostic tool. This is proposed as a guide for clinical practice and further research.
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After decades of finding a range of cognitive functions both in visual and phonological domains that correlate with reading performance, there are in recent years attempts to solve the causation versus correlation dilemma in finding a core deficit in developmental dyslexia (DD). Thus, longitudinal studies that aim to predict reading difficulties from studies done in pre-reading years and reading-level matched studies that try to factor out the effect due to lack of reading in DD cohorts, have helped identify two possible candidates to be added to the classical phonological suspect. One is a deficit in visuo-spatial attention that underpins our ability to selectively attend to individual objects in a cluttered world, which is fundamental in being able to identify letters and words in a text such as the one you are reading now. The other is an impairment in synchronised neuronal oscillations that may be crucial in mediating many cortical functions and also communication between brain regions. The latter may be a general deficit affecting many areas of the brain and thus underlie the wide-ranging co-morbidities in DD. However, that neuronal synchrony is a critical mediator in visual attention, brings the two suggestions into one hypothesis of a core deficit that triggers in some young children a great reluctance to read, putting them at a handicap in comparison to other children. This deprives them of the advantage that normal readers have in development of those visual and phonological processes that are needed for reading. This insight into aetiology may help in developing new remediation strategies, specifically aimed at improving visual attention and neuronal synchrony.
Article
Some people doubt that the concept of developmental dyslexia (DD) is useful at all because the phonological weaknesses seen in DD cannot be distinguished from those found in every person with poor reading skills, whatever their cause. Here I argue that true DD is characterized by poor temporal processing, hence impaired visual and auditory sequencing, that is caused by impaired development of transient/magnocellular (M-) systems throughout the brain. These deficits can be measured to distinguish the causes of the phonological weaknesses in DD from those causing similar deficits in other types of poor reading; Importantly this knowledge can be exploited to develop effective improvements in treatment. The evidence for impaired visual magnocellular function in many, if not all, people with dyslexia is now overwhelming; it is supported not only by psychophysical tests of M- function, but also by electrophysiological, eye movement, attentional, imaging, interventional and genetic findings. Analogously, auditory temporal processing is mediated by auditory transient, "magnocellular', processing systems, and evidence is accumulating persuasively that this system is also impaired in dyslexics. I briefly introduce the idea that 'motor magnocellular systems' may also be impaired in dyslexia, then consider genetic, immunological and nutritional factors that interact to cause the impaired magnocellular phenotype. I then discuss why the dyslexic phenotype is so common by speculating about what strengths it might confer that would maintain the responsible genes in the human genome.
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Purpose: There are many anecdotal claims and research reports that coloured lenses and overlays improve reading performance. Here we present the results of a systematic review of this literature and examine the quality of the evidence. Methods: We systematically reviewed the literature concerning the effect of coloured lenses or overlays on reading performance by searching the PsychInfo, Medline and Embase databases. This revealed 51 published items (containing 54 data sets). Given that different systems are in use for issuing coloured overlays or lenses, we reviewed the evidence under four separate system headings (Intuitive, Irlen, Harris/Chromagen and Other), classifying each published item using the Cochrane Risk of Bias tool. Results: Although the different colour systems have been subjected to different amounts of scientific scrutiny, the results do not differ according to the system type, or whether the sample under investigation was classified as having visual stress (or a similarly defined condition), reading difficulty, or both. The majority of studies are subject to 'high' or 'uncertain' risk of bias in one or more key aspects of study design or outcome, with studies at lower risk from bias providing less support for the benefit of coloured lenses/overlays on reading ability. While many studies report improvements with coloured lenses, the effect size is generally small and/or similar to the improvement found with a placebo condition. We discuss the strengths and shortcomings of the published literature and, whilst acknowledging the difficulties associated with conducting trials of this type, offer some suggestions about how future trials might be conducted. Conclusions: Consistent with previous reviews and advice from several professional bodies, we conclude that the use of coloured lenses or overlays to ameliorate reading difficulties cannot be endorsed and that any benefits reported by individuals in clinical settings are likely to be the result of placebo, practice or Hawthorne effects.
Article
Claims that coloured filters aid reading date back 200 years and remain controversial. Some claims, for example, that more than 10% of the general population and 50% of people with dyslexia would benefit from coloured filters lack sound evidence and face validity. Publications with such claims typically cite research using methods that have not been described in the scientific literature and lack a sound aetiological framework. Notwithstanding these criticisms, some researchers have used more rigorous selection criteria and methods of prescribing coloured filters that were developed at a UK Medical Research Council unit and which have been fully described in the scientific literature. We review this research and disconfirm many of the more extreme claims surrounding this topic. This literature indicates that a minority subset of dyslexics (circa 20%) may have a condition described as visual stress which most likely results from a hyperexcitability of the visual cortex. Visual stress is characterised by symptoms of visual perceptual distortions, headaches, and eyestrain when viewing repetitive patterns, including lines of text. This review indicates that visual stress is distinct from, although sometimes co-occurs with, dyslexia. Individually prescribed coloured filters have been shown to improve reading performance in people with visual stress, but are unlikely to influence the phonological and memory deficits associated with dyslexia and therefore are not a treatment for dyslexia. This review concludes that larger and rigorous randomised controlled trials of interventions for visual stress are required. Improvements in the diagnosis of the condition are also a priority.