Journal Information
Vol. 3. Issue 2.
Pages 94-101 (April - June 2010)
Share
Share
Download PDF
More article options
Visits
573
Vol. 3. Issue 2.
Pages 94-101 (April - June 2010)
Original article
Open Access
A placebo-controlled trial of tinted lenses in adolescents with good and poor academic performance: reading accuracy and speed
Ensayo controlado con placebo sobre lentes coloreadas en adolescentes con buen y mal rendimiento académico: precisión y velocidad lectora
Visits
573
Genís Cardona
Corresponding author
gcardona@oo.upc.edu

Corresponding author. Escola Universitària d’Òptica i Optometria de Terrassa, Violinista Vellsolà, 37, 08222 Terrassa, Barcelona, Catalonia, Spain. Tel.: +34 93 739 8774.
, Rosa Borràs, Elvira Peris, Marina Castañé
Research Group of Centre Universitari de la Visió, Optics and Optometry Department, Technical University of Catalonia, Barcelona, Spain
This item has received

Under a Creative Commons license
Article information
Abstract
Full Text
Bibliography
Download PDF
Statistics
Figures (6)
Show moreShow less
Tables (1)
Table. Demographic data and baseline reading speed and accuracy (in words read and number of errors per minute)
Abstract
Purpose

A placebo-controlled, double-masked study was designed in order to evaluate the effect of tinted lenses in adolescents with good and poor academic performance.

Methods

Teenagers from two different age groups were enrolled in this study, after ascertaining that no uncorrected visual anomalies were present. A rate of reading test was developed for Catalan as a first language and students were asked to read it aloud, in two different sessions. Students first read the test without lenses and, later, they read it again without lenses, with their lenses of choice and with a placebo set of clear lenses. Reading speed and accuracy were monitored.

Results

No significant difference was encountered between the baseline reading speed and accuracy from the first and second sessions, thus ruling out any effect due to experience or training. When comparing reading speed and accuracy without lenses, in placebo conditions, and with tinted lenses, reading accuracy was discovered to be more sensitive than reading speed in order to differentiate between these conditions. These differences were more noticeable when the group with poor academic performance was evaluated, in contrast to the group with good academic performance or the whole group.

Conclusion

It was concluded that reading accuracy should be evaluated as well as reading speed and that lenses were more beneficial if only adolescents with poor academic performance were targeted.

Keywords:
Academic performance
Coloured filters
Reading accuracy
Reading speed
Visual stress
Resumen
Objetivo

Se diseñó un estudio doble enmascarado, controlado con placebo para evaluar el efecto de las lentes coloreadas en adolescentes con buen y mal rendimiento académico.

Métodos

Se incluyeron en el estudio adolescentes de dos grupos de edad diferente, tras determinar la ausencia de anomalías visuales no corregidas. Se desarrolló un test de precisión y velocidad lectora para el catalán como primer idioma y se solicitó a los estudiantes que leyeran en voz alta en dos sesiones diferentes. Primero, los estudiantes leyeron la prueba sin lentes y, más tarde, la leyeron de nuevo sin lentes, con las lentes de su elección y con una serie placebo de lentes transparentes. Se monitorizaron la velocidad y precisión lectoras.

Resultados

No se encontraron diferencias significativas entre la velocidad y precisión lectora basal a partir de la primera y segunda sesiones, lo que, por tanto, descartó cualquier efecto debido a la experiencia o adiestramiento. Cuando se comparó la velocidad y precisión lectora sin lentes, en las condiciones placebo, y con lentes coloreadas, se identificó que la precisión era más sensible que la velocidad lectora para diferenciar entre estas condiciones. Estas diferencias fueron más destacadas cuando se valoró al grupo con mal rendimiento académico, en comparación con aquél con un buen rendimiento o el grupo en conjunto.

Conclusión

Se concluye que es preciso valorar la precisión al igual que la velocidad lectora y que las lentes sólo fueron más beneficiosas si la prueba se destinó a adolescentes con un mal rendimiento académico.

Palabras clave:
Rendimiento académico
Filtros de color
Precisión lectora
Velocidad lectora
Estrés visual
Full Text
Introduction

The term visual stress, previously Scotopic Sensitivity Syndrome, refers to the symptoms of asthenopia, visual perceptual distortion and, generally, visual fatigue, which accompany reading, even in the absence of any uncorrected refractive error or orthoptic anomaly. 1,2 Meares first reported a condition in which schoolchildren manifested reading difficulties when presented with certain combinations of text font, interlinear spacing and background versus text contrast. 3 Irlen further discussed these findings and advanced the possibility of using coloured filters as a means of ameliorating the symptoms.4

Patients often describe perceptual distortion as blurring of text, doubling, moving or flickering letters or lines and shadowy outlines. Many of these symptoms are also acknowledged by patients with photosensitive epilepsy, autism, 5 migraine, 6 dyslexia and multiple sclerosis. 7 There have been many attempts at finding a common ground between these conditions in order to progress in the understanding of their aetiology. Patterns of stripes have been identified as triggers of discomfort (pattern glare) and headaches, provided that they sustain a spatial frequency within two octaves of three cycles per degree. 8,9 Some texts found in common school reading material may be equivalent to a pattern of horizontal stripes with a spatial frequency within this range. 10 These discoveries led to the suggestion of either a magnocellular visual system deficit or a cortical hyperexcitability as competing hypotheses of most of these conditions, particularly in the case of dyslexia. 11 However, as visual stress studies assessing the magno function have so far been unable to prove it to be abnormal, 1,12 the second line of inquiry is gaining acceptance as the generic explanation for visual stress. Indeed, Wilkins has suggested that colour filters may change the distribution of firing within certain areas of the visual cortex, 13 thus decreasing the summation of stimuli in such hyperexcitable regions as the visual area V2, where colour sensitive cells are organized topographically according to their chromaticity. 14 This last theory would require visual stress and dyslexia to be independent conditions, although there is some evidence that visual stress is more prevalent in dyslexia.15

Visual stress has usually been diagnosed by evaluating the success of its treatment, although recent efforts have been directed towards the development and normalization of a computerized visual stress screener 16 and a Pattern Glare Test.17

The use of colour to treat the symptoms associated with visual stress has been approached from three different directions: coloured overlays, tinted lenses and coloured ambient illumination.

The majority of placebo-controlled trials study the effect of coloured overlays on reading speed and accuracy. Wilkins developed the Intuitive Overlays, which consist of nine differently coloured overlays and a grey overlay that can additionally be placed one on top of another of the same or similar chromaticity so as to obtain a pallet of 27 colours. 18 Extensive testing with these overlays has revealed that coloured overlays provide a greater benefit than both clear overlays and grey overlays that reduce the contrast and luminance by a similar amount, thus exploring the likelihood of the placebo effect as a possible explanation of the findings. 19 The choice of colour has been found to present a high level of consistency and replicability among individuals and this consistency to be beneficial. Thus, when presented with the option, children who chose the same colour on two different testing sessions showed a greater improvement in reading speed than those who chose a similar colour and this group of children, in turn, performed better than those who opted for altogether different colours on each session. 20 Interestingly, the choice of colour has proved to be distributed evenly among those colours available, although the work of Scott and co-workers noted a weak relationship between colour and ocular accommodation, in which the colours reflecting longer wavelengths were chosen by children who had greater amplitude of accommodation.2

The benefits gained by the use of colour overlays have proved to be dependent on the precision of colour selection. Reading speed decreases with departures from the chosen optimal chromaticity, whether as a result of changes in saturation or in hue. 21 This finding may be of importance when colour overlays are used under lighting conditions that differ from those under which the most beneficial colour was selected 22 or when the choice of colours is limited. This last aspect has been recently examined by Smith and Wilkins 23 by means of comparison between the Intuitive Overlays and the Reading Rulers, developed by Crossbow Education Ltd. The Reading Rulers present a set of five differently coloured overlays which are large enough to cover two lines of text and which are designed to be repositioned over the portion of text that is being read. The limited choice of colours, together with the fact that they do not allow for combination, resulted in a failure to exhibit any increment in reading speed with their use.

It is relevant to note that, for a particular patient, the most beneficial colour for overlays is not necessarily the same as that considered to be the optimal for tinted lenses. Lightstone and co-workers designed a study in which patients were asked to read with no colour, with the chosen overlay, with the chosen lenses and with lenses matching the colour of the chosen overlay. 24 Only the second and third conditions resulted in a significant improvement. The reason for these discrepancies seems to be attributable to the colour adaptation that occurs when the entire field is coloured, such as in the case of tinted lenses, even though the exact governing mechanism remains unclear. 25 Precision tinted lenses are generally accepted to be the best treatment for visual stress, with overlays basically consider ed a screening tool.21

Haploscopic filters are a particular scenario of the application of coloured lenses to improve reading skills. Commercialized under ChromaGenTM, this FDA approved system of filters consists of 16 lenses with eight different chromatic characteristics (i.e. two lenses of each colour). Patients choose the optimum colour for their non dominant eye first and, with the chosen lens in front of this eye, they determine the filter for the dominant eye. It is perhaps surprising that this system sometimes results in a person being prescribed different colours in each eye. It should be noted that this is a feature of the Chromagen system, and that with the more widely used Intuitive Colorimeter and Irlen systems the same colour is used for each eye. The Chromagen system was used in a randomized, double-masked, placebo-controlled trial in patients with dyslexia, resulting in a statistically significant improvement of the text distortion reported by the patient, which could not be explained solely by placebo effects 26. The number of colours that is available with this system is much less than that indicated as necessary by Wilkins and coworkers, 21 a limitation that will be considered further in the discussion, as the use of ChromaGen in the present study may have led to an underestimation of the benefits of coloured filters.

The effect of both overlays and coloured lenses on reading speed and accuracy is usually evaluated by means of the Wilkins Rate of Reading Test. 27 15 repeated monosyllabic simple words are randomly distributed over 10 lines of text, each word appearing once in each line, thus minimizing the syntactic and semantic properties of the text. The text utilizes closely packed words printed in a small font, so as to allow for a greater manifestation of any visual problem. The final score, in words per minute, is obtained by subtracting errors from the total word count, hence consisting in a combined speed and accuracy score. This test is superior over similar tests in that it requires little comprehension and very basic reading skills. As such, its developers claim that performance in this measure is independent of the language skills of the age group under study. Besides, it has been proved to have a high test-retest reliability, both in immediate retest (correlation between test and retest greater than 0.8) and when test and retest were eight weeks distant. 20,27

The aims of this study were, firstly, to design a suitable rate of reading test for both the age groups under evaluation and the particular characteristics of our language (Catalan) and, secondly, to investigate the effect of tinted lenses on the reading speed and accuracy of a group of good students as compared with another group of students with a poorer academic performance. Additionally, the degree of testretest improvement which could be attributed to training was explored, as well the intervention and importance of placebo effects.

MethodsSubjects

Students from a state school near Barcelona were recruited for this study after obtaining a signed informed consent from their parents or legal guardians. Subjects were allocated to one of four groups according to age and academic performance. Subjects from groups 1 and 2 were between 14 and 15 years old, whereas groups 3 and 4 included subjects aged between 16 and 17. Good students were allocated to groups 1 and 3 and poor students to groups 2 and 4. A poor academic performance was defined as consistent negative qualifications obtained from two or more subjects that academic year, with the exclusion of arts, technology and physical education, provided that such low scores could not be attributed to other factors such as language problems, mental health or personality disorders (information available in the school medical files). Neither the examiner, nor the student, knew which group each person had been assigned to, even though certain clues were logically obvious to a keen observer.

An initial optometric examination for near vision was administered to all students in order to rule out any significant non corrected visual problem. Exclusion criteria were uncorrected retinoscopic findings larger than 1 dioptre in either myopia, hyperopia or astigmatism, near visual acuity lower than 20/30, heterophoria at near of more than 4 prism dioptres of esophoria or 10 prism dioptres of exophoria, near point of convergence over 15 centimetres, manifest cover test deviation, monocular amplitude of accommodation lower than 10 dioptres (push-up technique) and colour vision anomalies (as measured with the Ishihara test, 24 plates version, 1974).

Following the various exclusion criteria, a total of 56 students were enrolled in this study, with a similar proportion of males and females.

Rate of reading test

Catalan language differs from English both grammatically and phonetically. Therefore, a rate of reading test was developed for speakers of Catalan as first language and also for the age groups under evaluation. School texts for students of these age ranges were perused in order to compile a list of suitable, simple, commonly used words. The final version of the test was considered to be suitable for the aims of this study by an external team of educational psychologists.

The resulting text consisted of different combinations of mono, bi and trisyllabic words of increasing difficulty, that is, the first lines of the text contained more monosyllabic words and the last lines more trisyllabic ones. Texts were printed on Times New Roman, with a 9 point font and simple interlinear spacing. Text width and height was of 93 and 38 millimetres respectively (Figure 1). Eight different versions of the text were constructed, allowing for a better randomization of word distribution. The special characteristics of the Catalan test were believed to allow the autonomous computation of speed and accuracy. Consequent ly, a slow reader who makes no errors and a fast reader with plenty of mistakes would score the same in the Wilkins Rate of Reading Test but not in our test.

Figure 1.

Example of text employed in this study for the evaluation of reading speed and accuracy.

(0.1MB).
Tinted lenses

As mentioned above, a set of coloured lenses was used in this study. This set consists of eight pairs of tinted lenses (Figure 2) from which the patient is asked, firstly, to select the most appropriate colour for the non dominant eye and, secondly, and with this chosen filter in place, to decide on a colour for the contralateral dominant eye. The rationale behind this modus operandi resides in the fact that if the subject finally prefers to use only one lens, the tint would be less noticeable or distracting if worn in front of the non dominant eye instead of the dominant one. It is common for subjects to select lenses for both eyes, even if the colour of choice often differs. Colours are chosen by randomly placing the eight different tinted lenses in front of one eye and the other and asking the subjects to select the lens which provides them with the best subjective visual comfort.

Figure 2.

Set of coloured lenses.

(0.09MB).
Procedure

A total of two sessions was necessary to conduct the study. The first session was devoted to defining the final groups of students for further evaluation and to determine baseline reading speed and accuracy as well as to investigate ocular dominance. Baseline reading speed and accuracy measurements were repeated at the start of the second session, following which students selected their tinted lenses of choice and were asked to read, in a random order, with those lenses and with a placebo set of lenses.

Thus, all students from the target age groups followed a complete standard optometric examination and the exclusion criteria presented above were implemented. Ocular dominance was decided on the basis of which eye was preferred by the subject when, while looking at the examiner through the central hole of an opaque card which was held at arm's length with both hands, he or she was asked to move the card closer to his or her face without losing fixation.

Subjects were then handed one of the eight rate of reading tests and asked to read it aloud during one minute. The number of correct words and, therefore, errors, was noted down. This result was later used as base reading speed and accuracy.

The second session, which took place 15 days later, started by the repetition of the reading speed and accuracy measurements on another randomly chosen reading card. The aim of this repetition was to investigate any possible effects due to training or subject experience and to establish the baseline reading speed and accuracy for the second session. Lenses were then selected, according to the procedure already described. Finally, subjects were asked to read aloud from two new, randomly chosen reading cards for an interval of one minute each, the order being altered also at random between the tinted lenses of choice and a placebo set of clear lenses. Subjects were convincingly told that these clear lenses had a new invisible tint, recently developed to provide the same effect as the coloured lenses. This type of distractor has been utilised before in published literature.28

Even if, on the one hand, both examiner and subjects were obviously aware of the age group that was under investigation, on the other hand, they were ignorant as to which subject was allocated to each academic performance group.

Lighting conditions, which corresponded to those of a well illuminated classroom (approx. 500 lux), remained constant during both sessions. The Declaration of Helsinki tenets of 1975 (as revised in Tokyo in 2004) were followed throughout the study and the research was approved by the Ethics Committee of the Technical University of Catalonia.

Data analysis

Paired data Student's t-tests were used to investigate the statistical significance of the differences between baseline reading speed and accuracy and the results obtained with the coloured or the placebo lenses, as well as between the tinted and placebo lenses themselves. A P-value of.05 or less was considered to denote statistical significance.

Additionally, data were also analysed through tests of Pearson's correlation, whenever it was deemed appropriate.

Results

As was to be expected, baseline reading speed and accuracy was highly sensitive to both the age of the subject and his or her academic performance. Thus, taken as a whole, older subjects read faster than younger ones. Good students from the younger age group read 15 words per minute (wpm) more than their poorer counterpart, this difference decreasing to 10 wpm for the older age group. The number of errors per minute displayed a similar trend, that is, older students read more accurately than younger ones and, within each age group, good students performed better than poor ones. It may be relevant to note that poor students from the older age group read significantly slower and with more errors than good students from the younger age group, even if they were, on average, two years older. Table summarizes descriptive statistics regarding demographic data and baseline reading speed and accuracy.

Table.

Demographic data and baseline reading speed and accuracy (in words read and number of errors per minute)

Age 14 to 15Age 16 to 17
Age, mean ± SD Gender, M;F  Base reading speed and accuracy  Age, mean ± SD Gender, M;F  Base reading speed and accuracy 
Good academic performance1114.55±0.52  113.18  15  16.64±0.52  112.14 
10M; 1F  2.45    9M; 6F  2.07 
Poor academic performance1414.36±0.5  97.93  16  16.71±0.59  101.82 
8M; 6F  3.43    5M; 11F  3.71 

No statistically significant differences were discovered between the baseline reading speeds and accuracy measured from both sessions, neither for the whole group (P=.21) nor for any paired combination of age and academic performance (all P>.05). Indeed, a good correlation (r=0.74; P<.0001) was encountered when plotting together the reading speeds for the first and second sessions (Figure 3).

Figure 3.

Scatter plot and correlation line of the baseline reading speed results obtained during the first and second sessions (r=0,74; p<.0001; y=0.913× + 12.477).

(0.07MB).

All subjects selected two coloured lenses, one for each eye. 46.4 % of the subjects manifested their preference for lenses of exactly the same colour whereas the rest favoured different colours. It was not possible to identify any particular linking pattern between same or different colours and good or poor academic performance (P=.87) or homonymous or crossed ocular/hand dominance (P=.81). Furthermore, when comparing reading speed and accuracy with lenses of the same or different colour, results failed to reveal any statistically significant disparity between these groups of subjects (all P>.05).

Taken the group as a whole, a statistically significant difference was encountered when comparing baseline reading speed and reading speed with both placebo lenses (P=.0008) and tinted lenses (P=.0009) (Figure 4a). Placebo and chromatic conditions were not found to be different (P=.86). When analysing the number of errors that students committed during their reading, no statistically significant difference was revealed between baseline results and placebo lenses (P=.17) but a notable improvement was accomplished with tinted lenses (P=.0002). In this case, placebo and chromatic conditions displayed a significant disparity (P=.038).

Figure 4a.

Baseline, placebo and chromatic reading speed (in wpm) of the group as a whole.

(0.05MB).

A further analysis of the results according to the allocation of students in groups of dissimilar academic performance revealed interesting differences. Thus, on the one hand, good students evidenced statistically significant differences between baseline reading speed and reading with both placebo lenses (P=.0007) and chromatic filters (P=.016) (Figure 4b) and also between baseline errors and errors committed while wearing placebo lenses (P=.031) and tinted lenses (P=.011). In this group of students it was not possible to ascertain significant differences in behaviour between placebo and tinted lenses in either reading speed (P=.099) or accuracy (P=.71). On the other hand, even if poor students failed to elucidate any difference between baseline reading speed and reading with placebo lenses (P=.24) but showed an apparent improvement with tinted lenses (P=.028) (Figure 4c), a subsequent investigation was not successful in proving a statistically significant difference between the behaviour of placebo and chromatic lenses (P=.17). This was not the case of reading accuracy, where with placebo lenses poor students read almost as accurately as with no lenses whatsoever (P=.75) but displayed a pronounced improvement as soon as reading was repeated with tinted lenses (P=.006). Placebo and chromatic conditions were found to be significantly different (P=.038).

Figure 4b.

Baseline, placebo and chromatic reading speed (in wpm) of good students.

(0.05MB).
Figure 4c.

Baseline, placebo and chromatic reading speed (in wpm) of poor students.

(0.05MB).
Discussion

A first approximation to the results reveals a surprisingly low baseline reading speed, both for the whole group of students and for each age group analyzed individually. Indeed, published Catalan reading speeds for the same age groups ranges from 140/169 wpm for younger students to 170/189 wpm for older students. These scores are significantly better than the results obtained from the groups of students that participated in the present study.

It may be stated, however, that the tests which are commonly used to evaluate reading speeds do not follow the same principles as the Catalan reading test which was employed in the present study and do not avoid the presence of comprehension clues that tend to significantly increase the number of words correctly read. A clear understanding of these factors is essential to allow for a standardized reading speed measurement that may be easily interpreted and analysed without having to consider the particular comprehension clues that might be found in each text. In this sense, the test of reading speed that was utilized in this study is considered to be of optimal characteristics. Furthermore, the text was sufficiently sensitive to clearly classify students according to their academic performance and, thus, it might be used as an additional tool for the evaluation of this performance, together with conventional examination resources, always taking into account that artistic and technological subjects were not included in the appraisal of the academic profile of each particular student.

It must be acknowledged that the Catalan reading test was designed keeping in mind that Catalan language (as well as Spanish) is quite different from English in many aspects, one of which is the frequency of monosyllabic words. Indeed, most Catalan words are bi or trisyllabic, and meaningful monosyllabic Catalan words are sparse (if articles and prepositions are not included). It was therefore believed that reading accuracy could play a more important role in Catalan language than English (an error in a trisyllabic word might lead to this word not being read at all). While in a purely monosyllabic text, reading speed and reading errors are probably measuring the same, the Catalan reading test was believed to evaluate both concepts independently. It should be noted that these features of the test design make it very different to the Wilkins Rate of Reading Test, thus preventing any direct comparison of the results collected with this new Catalan test with those obtained in previous research with the Wilkins Rate of Reading Test.

The comparison of baseline reading speeds from session one and two revealed that learning and training effects were nonexistent. This finding, which was also encountered by Wilkins and co-workers, 20 may be explained by taking into consideration several factors. Thus, on the one hand, the interval between both sessions was of several days. On the other hand, excluding comprehension clues from the texts, all subjects could rely on in order to gain an improvement in their skills by means of training was the actual memory of the exact word order which comprised each text. This factor could have been of significance if only one text was used or if more reading sessions had taken place than the number of different texts which were employed. As it was, only four randomly chosen texts were read, out of a total of the eight different versions which were available.

Filter selection proved to be bilateral in all cases, that is, all subjects preferred to wear a coloured lens in front of each eye. Almost half of the subjects choose lenses of identical chromaticity for both eyes. This finding somehow undermines the philosophy which governs lens selection. Indeed, if all subjects end up with a pair of lenses, the need to start lens selection in the non dominant eye in order to minimize any collateral effect due to the use of colour filters is less justified. Swarbrick and colleagues reported similar results in this aspect. 29

This particular set of coloured lenses offers a relatively narrow range of colours for the subject to choose from. This might be of special relevance for the outcome of the study and for the performance, in general, of the lenses. Wilkins and collaborators, 22 during the evaluation of the effect of ambient illumination chromaticity on reading speed, revealed that a moderately small departure (of the order of 6 JNDs) from the colour of choice substantially decreased any advantage which might have been gained by the initial colour selection. Therefore, results seem to be highly sensitive to the precision of the colour that each individual deems to be the most appropriate. This precision was not obtainable with the present set of lenses. Thus, it may be safely speculated that a more noticeable effect would have arisen if this limitation could have been overcome, in other words, the present study is likely to have underestimated the benefit that can be obtained from precision tinted lenses.

Notwithstanding the above appreciation, a statistically significant difference was encountered when comparing baseline reading speed and reading speed through coloured filters (an improvement of 5 wpm or more was usual). It may be noticed, however, that an analysis of the group as a whole exposed a similar statistically significant difference between baseline reading speed and reading speed through placebo lenses. These results are in agreement with the work of Robinson and Foreman, in which they failed to encounter any noticeable improvement with coloured filters over placebo lenses when evaluating the performance of students with good or normal academic grades. 30

Consequently, one of the most interesting findings of the present study was the significant difference that arose when comparing the reading speeds with filters and with placebo lenses of a selected group of students with poor academic grades. Indeed, when students with poor academic performan ce were targeted, a noticeable improvement in their reading speed was accomplished if the selected tinted lenses were worn, while little benefit was obtained from placebo lenses. Previous studies did not fail to observe this specific advantage of coloured filters over placebo conditions when the group under investigation was defined by their academic performance, independent of their age. Positive results were attained from both a group of schoolchildren and another of adult students. 31,32 Unfortunately, however, a further analysis comparing placebo and tinted lenses did not disclose the level of statistical significance that was considered appropria te at the beginning of the study. Reading accuracy, nevertheless, proved to be much more sensitive to the differences between placebo and tinted lenses, giving rise to statistically significant differences between the conditions under evaluation. This conclusion relates to the new reading test that was developed for this study, and this observation cannot be extrapolated to the Wilkins Rate of Reading Test, which provides a test score that takes account of most types of error as well as rate. Additionally, the actual contribution of the placebo set of lenses that was utilized in this study is uncertain and, although this type of distractor has been implemented before, 28 further research is required to validate its effectiveness.

A literature research gave rise to few publications in which reading accuracy was assessed in addition to reading speed. Mitchell and co-workers reported a statistically significant improvement in visual discomfort symptoms with the use of coloured lenses in a group of subjects with visuoperceptual reading disabilities. 33 However, the same authors described inconsistent results when reading speed and accuracy were evaluated, with some subjects gaining a perceptible advantage with their lenses while others performed as well with tinted lenses as in placebo conditions. The need to correctly discover the most suitable target group was stressed.

In conclusion, with the new reading test described here, the evaluation of reading accuracy as well as reading speed and the precise identification of the group or groups of subjects which shall gain the biggest profit from this form of treatment might be the first step towards a better understanding of the neurophysiologic mechanisms at work and to helping these patients with the correct combination of coloured filters, overlays or ambient illumination. The exploration of this rich and extremely complex field of research, both via transversal and longitudinal studies, and in larger and more diverse samples of subjects, is of great importance as every little step may yield benefits of scientific and clinical relevance.

Conflict of interest

None of the authors claims any commercial interest in ChromagenTM lenses nor is, in any way, related to the manufacturer or distributor of this or any other brand of products of this type.

Acknowledgements

The authors would like to thank the students and staff of the Escola Municipal del Treball, Institut Politècnic of Granollers, for their kind assistance and voluntary participation in this study.

References
[1.]
B.J.W. Evans, A. Busby, R. Jeanes, A.J. Wilkins.
Optometric correlates of Meares-Irlen Syndrome: a matched group study.
Ophthal Physiol Opt., 15 (1995), pp. 481-487
[2.]
L. Scott, H. McWhinnie, L. Taylor.
Coloured overlays in schools: orthoptic and optometric findings.
Ophthal Physiol Opt., 22 (2002), pp. 156-165
[3.]
O. Meares.
Figure/ground brightness contrast and reading disabilities.
Visible Language, 14 (1980), pp. 13-19
[4.]
Irlen H. Successful treatment of learning difficulties. Annual Convention of the American Psychological Association, Anaheim, California; 1983.
[5.]
A.K. Ludlow, A.J. Wilkins, P. Heaton.
The effect of coloured overlays on reading ability in children with autism.
J Austism Dev Disord, 36 (2006), pp. 507-516
[6.]
A.J. Wilkins, J. Huang, Y. Cao.
Prevention of visual stress with migraine with precision spectral filters.
Drug Dev Res., 68 (2007), pp. 469-475
[7.]
B.N. Newman Wright, A.J. Wilkins, Y. Zoukos.
Spectral filters can improve reading and visual search in patients with multiple sclerosis.
J Neurol., 254 (2007), pp. 1729-1735
[8.]
A.J. Wilkins, C.D. Binnie, C.E. Darby.
Visually-induced seizures.
Prog Neurobiol, 15 (1980), pp. 86-117
[9.]
A.J. Wilkins, M.I. Nimmo-Smith, A. Tait.
A neurological basis for visual discomfort.
Brain, 107 (1984), pp. 989-1017
[10.]
A.J. Wilkins, J. Huang, Y. Cao.
Visual stress theory and its applications to reading and reading tests.
J Res Read., 27 (2004), pp. 152-162
[11.]
I. Iovino, J.M. Fletcher, B.G. Breitmeyer, B.R. Foorman.
Colored overlays for visual perceptual deficits in children with reading disability and attention deficit/hyperactivity disorder: are they differentially effective?.
J Clin Exp Neuropsychol, 20 (1998), pp. 791-806
[12.]
A. Simmers, L.S. Gray, A.J. Wilkins.
The influence of tinted lenses upon ocular accommodation.
Vision Res., 41 (2001), pp. 1229-1238
[13.]
A.J. Wilkins.
Reading through colour.
Wiley, (2003),
[14.]
Y. Xiao, Y. Wang, D.J. Fellerman.
A spatially organized representation of colour in macaque cortical area V2.
Nature, 421 (2003), pp. 535-539
[15.]
I. Kriss, B.J.W. Evans.
The relationship between dyslexia and Meares-Irlen syndrome.
J Res Read., 28 (2005), pp. 350-364
[16.]
C. Singleton, L. Henderson.
Computerized screening for visual stress in children with dyslexia.
Dyslexia, 13 (2007), pp. 130-151
[17.]
B.J.W. Evans, S.J. Stevenson.
The Pattern Glare Test: a review and determination of normative values.
Ophthal Physiol Opt., 28 (2008), pp. 295-309
[18.]
A.J. Wilkins.
Overlays for classroom and optometric use.
Ophthal Physiol Opt., 14 (1993), pp. 97-99
[19.]
A.J. Wilkins.
Coloured overlays and their effects on reading speed: a review.
Ophthal Physiol Opt., 22 (2002), pp. 448-454
[20.]
A.J. Wilkins, E. Lewis, F. Smith, E. Rowland.
Coloured overlays and their benefits for reading.
J Res Read., 24 (2001), pp. 41-64
[21.]
A.J. Wilkins, N. Sihra, M.I. Nimmo-Smith.
How precise do precision tints have to be and how many are necessary?.
Ophthal Physiol Opt., 25 (2005), pp. 269-276
[22.]
A.J. Wilkins, N. Sihra, A. Myers.
Increasing reading speed by using colours: issues concerning reliability and specificity, and their theoretical and practical implications.
Perception, 34 (2005), pp. 109-120
[23.]
L. Smith, A.J. Wilkins.
How many colours are necessary to increase the reading speed of children with visual stress? A comparison of two systems.
J Res Read., 30 (2007), pp. 332-343
[24.]
A. Lightstone, T. Lightstone, A.J. Wilkins.
Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ.
Ophthal Physiol Opt., 19 (1999), pp. 279-285
[25.]
M. Waldie, A.J. Wilkins.
How big does a coloured overlay have to be?.
Ophthal Physiol Opt., 24 (2004), pp. 57-60
[26.]
D. Harris, S.J. MacRow-Hill.
Application of Chromagen Haploscopic lenses to patients with dyslexia: a double-masked placebo-controlled trial.
J Am Optom Assoc, 70 (1999), pp. 629-640
[27.]
A.J. Wilkins, R.J. Jeanes, P.D. Pumfrey, M. Laskier.
Rate of Reading Test: its reliability, and its validity in the assessment of effects of coloured overlays.
Ophthal Physiol Opt., 16 (1996), pp. 491-497
[28.]
J. Bouldoukian, A.J. Wilkins, B.J.W. Evans.
Randomized controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties.
Ophthal Physiol Opt., 22 (2002), pp. 55-60
[29.]
H.A. Swarbrick, P. Nguyen, T. Nguyen, P. Pham.
The ChromaGen contact lens system: colour vision test results and subjective responses.
Ophthal Physiol Opt., 21 (2001), pp. 182-196
[30.]
G.L. Robinson, P.J. Foreman.
The effects of Irlen Coloured filters on eye movement: a long term placebo controlled study.
Behavioral Optometry, 7 (1999), pp. 5-18
[31.]
N. Northway.
Predicting the continued use of overlays in school children-a comparison of the Developmental Eye Movement test and the Rate of reading test.
Ophthal Physiol Opt., 23 (2003), pp. 457-464
[32.]
B.J.W. Evans, J. Florence.
The effect of coloured filters on the rate of reading in an adult student population.
Ophthal Physiol Opt., 22 (2002), pp. 536-545
[33.]
C. Mitchell, D. Mansfield, S. Rautenbach.
Coloured filters and reading accuracy, comprehension and rate: a placebo-controlled study.
Percept Mot Skills, 106 (2008), pp. 517-532
Copyright © 2010. Spanish Council of Optometry
Journal of Optometry
Article options
Tools

Are you a health professional able to prescribe or dispense drugs?