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COLOURED OVERLAYS IMPROVE READING PERFORMANCE IN PEOPLE SUFFERING FROM VISUAL STRESS
Abstract and Figures
The ability to read fast and effortless, with good comprehension, is nowadays essential for an independent and successful academic, professional and social life. However, many people feel discomfort and see distortions when reading. This condition, called visual stress, is possibly a consequence of a visual cortex hyperexcitability due to the occurrence of stripped pattern on texts. Several studies have shown that the use over texts of transparent colored plastic sheets, known as overlays, significantly improve some reading-related parameters, and so, enhance reading fluency on an adult population. These overlays work through the absorption of part of the visible spectrum, less exposing and less stimulating the eye receptors sensitive to this specific region. The use of a customized overlays decreases visual stress and increases visual comfort, extending periods of reading and enabling decoding techniques and other reading strategies to be applied. The investigation of oculomotor and other reading related parameters can help in the analysis of the visual process during reading. This study aimed to analyze the number of fixations, the number of regressions, the span of recognition, the average duration of fixation, the number of words read per minute, the cross correlation and the comprehension rate of 62 adults suffering visual stress and with indication for coloured overlay intervention. All participants had normal uncorrected or corrected visual acuity and were free of eye or neurological diseases, other than the visual stress related. Participant's reading performances were measured by Visagraph System when reading within and without a personalized spectral overlay. Statistical analysis showed significant (p<.05) improvement between five of the seven analyzed reading parameters within overlay use in people suffering from visual stress, suggesting the effectiveness of spectral intervention in the improvement of reading performance in this population.
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Developmental dyslexia affects almost 10% of school-aged children and represents a significant public health problem. Its etiology is unknown. The consistent presence of phonological difficulties combined with an inability to manipulate language sounds and the grapheme-phoneme conversion is widely acknowledged. Numerous scientific studies have also documented the presence of eye movement anomalies and deficits of perception of low contrast, low spatial frequency, and high frequency temporal visual information in dyslexics. Anomalies of visual attention with short visual attention spans have also been demonstrated in a large number of cases. Spatial orientation is also affected in dyslexics who manifest a preference for spatial attention to the right. This asymmetry may be so pronounced that it leads to a veritable neglect of space on the left side. The evaluation of treatments proposed to dyslexics whether speech or oriented towards the visual anomalies remains fragmentary. The advent of new explanatory theories, notably cerebellar, magnocellular, or proprioceptive, is an incentive for ophthalmologists to enter the world of multimodal cognition given the importance of the eye's visual input.
Background:
Approximately one in ten students aged 6 to 16 in Ontario (Canada) school boards have an individual education plan (IEP) in place due to various learning disabilities, many of which are specific to reading difficulties. The relationship between reading (specifically objectively determined reading speed and eye movement data), refractive error, and binocular vision related clinical measurements remain elusive.
Methods:
One hundred patients were examined in this study (50 IEP and 50 controls, age range 6 to 16 years). IEP patients were referred by three local school boards, with controls being recruited from the routine clinic population (non-IEP patients in the same age group). A comprehensive eye examination was performed on all subjects, in addition to a full binocular vision work-up and cycloplegic refraction. In addition to the cycloplegic refractive error, the following binocular vision related data was also acquired: vergence facility, vergence amplitudes, accommodative facility, accommodative amplitudes, near point of convergence, stereopsis, and a standardized symptom scoring scale. Both the IEP and control groups were also examined using the Visagraph III system, which permits recording of the following reading parameters objectively: (i) reading speed, both raw values and values compared to grade normative data, and (ii) the number of eye movements made per 100 words read. Comprehension was assessed via a questionnaire administered at the end of the reading task, with each subject requiring 80% or greater comprehension.
Results:
The IEP group had significantly greater hyperopia compared to the control group on cycloplegic examination. Vergence facility was significantly correlated to (i) reading speed, (ii) number of eye movements made when reading, and (iii) a standardized symptom scoring system. Vergence facility was also significantly reduced in the IEP group versus controls. Significant differences in several other binocular vision related scores were also found.
Conclusion:
This research indicates there are significant associations between reading speed, refractive error, and in particular vergence facility. It appears sensible that students being considered for reading specific IEP status should have a full eye examination (including cycloplegia), in addition to a comprehensive binocular vision evaluation.
Forty-six children aged 12–16 were shown a page of meaningless text covered in random order by different plastic overlays, including seven that were various colours and one that was clear. By successive pairwise comparison each child selected the overlay that provided the greatest perceptual clarity of the text. The children with below-average reading ability were more likely to chose a coloured overlay, and they reported more perceptual difficulty on tasks devised by Irlen (1983). In separate sessions with and without the overlay of their choice, the children read for 15 minutes and performed a visual search task. The overlay had little effect on reading initially, but after about 10 minutes the children who chose a coloured overlay read more slowly without the overlay than with it. These children reported more symptoms of visual discomfort and showed signs of tiring when they read without the overlay. The visual search performance of the children who chose a coloured overlay was initially impaired but improved to normal levels when the overlay was used. Fourteen children aged 8–16 acted as chronological or reading age-matched controls, and undertook the reading and visual search tasks using a clear overlay which had no effect on performance.
Children in mainstream schools compared text on white paper with identical text covered in turn by each of ten differently-coloured plastic overlays. More than 50% reported improved perception with one or more colours, and were given the best colour to use. About half used the overlays for more than three months and their reading speed increased when the overlays were used. In Study I children were examined twice using different methods and examiners. 47% chose the same colour on both occasions, and showed the greatest improvement in reading fluency, reliable at retest. In Study II children were issued with a random colour, and the greatest improvements in reading speed occurred when the random colour was the same as that previously chosen. Phonological reading strategies were not related to visual symptoms, or the benefit from overlays. Across individuals, reading speed varied by a factor of more than three, for good and poor readers. Study III provided estimates of the prevalence of improvements based on a sample of 426 children from 12 schools: 5% of children read more than 25% faster with a coloured overlay.
(Table Presented) Individuals who suffer migraine, particularly migraine with visual aura (MwA), are susceptible to physiologically strong visual stimuli and find them aversive. Strong stimuli including bright light and certain visual patterns produce discomfort and perceptual illusions and can trigger migraine attacks. Perceptual illusions and visual discomfort are reported by most migraine sufferers and those with frequent headaches. These phenomena suggest that visual stimulation and consequent visual cortical activity contribute to the triggering of some migraine attacks. Perceptual illusions in MwA patients were found to be associated with hyper-activation in visual cortex. This excessive cortical activity is called visual stress. The cortex is generally hypothesized to be hyperexcitable in migraine, and this hyperexcitability could be the underlying mechanism of visual stress. It is hypothesized that visual stress results from too great a neural (hyperneural) activity in response to strong physiological sensory stimulation, particularly, but not exclusively, visual. A strong physiological visual input may cause a spread of excitation through hyperexcitable cortex, leading to neurons firing inappropriately and thereby resulting in perceptual illusions and distortions, and possibly promoting a migraine attack. Over the last 10 years, the use of colored filters to treat perceptual distortion of text has become common in many schools in Britain. The efficacy of precision spectral filters (PSF) in preventing migraine headache has been reported in several studies. One preliminary study revealed the suppressing effect of the PSF on visual cortical activity in a MwA patient, suggesting that it might be this reduction in cortical activation that is responsible for the reduction of the frequency of migraine attacks in those who benefited from the PSF. PSF offer a possible new prophylactic therapy for migraine. They are safe, free of side effects, and inexpensive.
Reports conversations with children attending a New Zealand reading clinic that indicate that the maximum brightness contrast of black-on-white print was a strong contributing factor in the children's reading disabilities. (Author/GT)
Purpose:
To construct and validate a test of sustained silent reading.
Methods:
Standardized 7300 and 7600 word passages were written to evaluate sustained silent reading. Two hundred forty subjects validated whether comprehension questions could discriminate subjects who did and did not read the passage. To evaluate test-retest properties, 49 subjects silently read the standardized passages on separate days. Sixty glaucoma suspect controls and 64 glaucoma subjects had their out loud reading evaluated with the MNRead card and an International Reading Speed Texts (IReST) passage, and their silent reading measured using the 7300 word passage. Sustained silent reading parameters included reading speed and reading speed slope over time.
Results:
Comprehension questions distinguished individuals who had and had not read passage materials. Bland-Altman analyses of intersession sustained reading speed and reading speed slope demonstrated 95% coefficients of repeatability of 57 words per minute (wpm) and 2.76 wpm/minute. Sustained silent reading speed was less correlated with MNRead (r = 0.59) or IReST passage (r = 0.68) reading speeds than the correlation of these two measures of out loud reading speed with each other (r = 0.72). Sustained silent reading speed was more likely to differ from IReST reading speed by more than 50% in rapid silent readers (odds ratio [OR] = 29, 95% confidence interval [CI] = 10-87), and comparisons of sustained and out loud reading speeds demonstrated proportional error in Bland-Altman analyses.
Conclusions:
Tests of out loud reading do not accurately reflect silent reading speed in individuals with normal vision or glaucoma. The described test offers a standardized way to evaluate the impact of eye disease and/or visual rehabilitation on sustained silent reading.
The relationship between dyslexia and visual stress (sometimes known as Meares-Irlen syndrome) is uncertain. While some theorists have hypothesised an aetiological link between the two conditions, mediated by the magnocellular visual system, at the present time the predominant theories of dyslexia and visual stress see them as distinct, unrelated conditions, a view that has received some support from studies with children. Studies of visual stress in adults are rare, yet recent reports of a high incidence of this phenomenon amongst university students with diagnosed dyslexia call for further investigation of the issue. This study sought to clarify the relationship between visual stress and dyslexia by comparing the reading performance of dyslexic and non-dyslexic adults with, and without, colour. Degree of susceptibility to visual stress was determined by means of a symptom rating scale. Optimal colour was determined using an Intuitive Colorimeter, which was also employed to assess reading speed under the two experimental conditions. Only the dyslexic students with high visual stress showed significant gains in reading speed when using optimal colour. The use of response to treatment (rather than symptomatology) as a diagnostic criterion for visual stress is questioned, especially when applied to adults, as this may give misleading findings. On the basis of reported symptomatology, students who experience high levels of visual stress are more likely to show improvements in reading rate with optimal colour if they also have dyslexia than if they do not have dyslexia. Although not establishing an aetiological link, these findings imply an interaction between the two conditions with major implications for theory, diagnosis and treatment.
Meares-Irlen Syndrome (MIS) is characterised by symptoms of visual stress and visual perceptual distortions that are alleviated by using individually prescribed coloured filters. Coloured overlays (sheets of transparent plastic that are placed upon the page) are used to screen for the condition. MIS is diagnosed on the basis of either the sustained voluntary use of an overlay or an immediate improvement (typically of more than 5%) on the Wilkins Rate of Reading Test (WRRT). Various studies are reviewed suggesting a prevalence of 20–34% using these criteria. Stricter criteria give a lower prevalence: for example, 5% of the population read more than 25% faster with an overlay. It has been alleged that MIS is more common in dyslexia, but this has not been systematically investigated. We compared a group of 32 dyslexic with 32 control children aged 7–12 years, matched for age, gender and socio-economic background. Participants were tested with Intuitive Overlays, and those demonstrating a preference had their rate of reading tested using the WRRT with and without their preferred overlay. Both groups read faster with the overlay, and more so in the dyslexic group. ANOVA revealed no significant effect of group, but a significant improvement in WRRT with overlay (p=0.009) and a significant interaction between group and overlay (p=0.031). We found a similar prevalence of MIS in the general population to that in previous studies and a prevalence in the dyslexic group that was a little higher (odds ratio for >5% criterion: 2.6, 95% confidence limit 0.9–7.3). The difference in prevalence in the two groups did not reach statistical significance. We conclude that MIS is prevalent in the general population and possibly a little more common in dyslexia. Children with dyslexia seem to benefit more from coloured overlays than non-dyslexic children. MIS and dyslexia are separate entities and are detected and treated in different ways. If a child has both problems then they are likely to be markedly disadvantaged and they should receive prompt treatments appropriate to the two conditions. It is recommended that education professionals as well as eye-care professionals are alert to the symptoms of MIS and that children are screened for this condition, as well as for other visual anomalies.