To discriminate the visual symptoms and signs of Meares-Irlen syndrome (MIS) and nonspecific dyslexia from other ophthalmologic diseases (NODs).
Forty-five patients were enrolled. Thirty four of the patients with MIS whose symptoms improved with tinted lenses comprised MIS group. The other 11 patients whose reading difficulty improved with other ocular therapy and did not require tinted lenses comprised NODs group. The main symptoms causing dyslexia and associated ocular diseases were evaluated.
The mean age was 17.9 ± 9.5 years in MIS group, and 19.3 ± 11.0 years in NODs group. In MIS group, the most common symptoms while reading were difficulty to move lines (85%), doubling (53%), and difficulty in bright condition (27%). On the other hand, blurring was the most common symptom in NODs group (45%). The associated ocular diseases in the two groups were refractive error (79% and 73%), dry eye (29% and 18%), and exophoria (6% and 27%), respectively.
Doubling, difficulty to move lines, and difficulty in bright condition while reading are main specific symptoms in MIS compared to nonspecific dyslexia from other ophthalmologic disorders.
Dyslexia is a specific learning difficulty that affects reading and comprehension. Generally speaking, primary dyslexia (developmental dyslexia) refers to children who have difficulty mastering the relationships between the spelling patterns of words and their pronunciations. There is good evidence that dyslexia can be ameliorated by systematic phonic teaching combined with phonological awareness training. The high rates of association of seemingly disparate neuropsychiatric disorders (including attention deficit hyperactivity disorder [ADHD] and motor disorders) raises important challenges for understanding these disorders [
In contrast, Meares-Irlen syndrome (MIS, previously known as scotopic sensitivity syndrome) is a condition characterized by reading difficulties that are mitigated by wearing colored filters of a specific tint. Meares [
However, the symptoms of MIS should be differentially diagnosed from other ophthalmologic disorders such as refractive errors, exophoria and posterior subcapsular cataracts, which have similar non-specific visual symptoms to MIS [
We investigated the visual symptoms and signs in patients who had visited our department for reading difficulties to characterize the specific clinical features of MIS and the variable spectrum of dyslexia for ophthalmologists.
The medical records of 45 patients from December 2009 were retrospectively reviewed. Main symptoms causing reading difficulties and associated ophthalmologic disorders were evaluated. The study followed the tenets of the Declaration of Helsinki and was approved by the institutional review board at Korea University Medical Center. All patients were selected through a brief questionnaire including assessment for any symptoms of eyestrain or visual perceptual distortion and other symptoms to determine which symptoms caused reading difficulty. An ophthalmic examination that included an assessment of visual acuity, refractive errors, the slit lamp examination, the tear break-up time, strabismus and retinal findings was also performed. We excluded patients who were younger than nine years old and those who were linguistically, intellectually or mentally challenged.
We conducted a thorough examination for dyslexia using the reading writing speed meter, which was developed to evaluate reading/writing abilities in Korea [
MISVIS (Incheon, Korea) filters consist of diverse colors of lenses. Each color provides four to five lenses with differences in the degree of darkness (
Forty-five patients with dyslexia were included in this study. We divided these patients into two groups. The MIS group (average age, 17.9 ± 9.5 years; range, 8 to 34 years) comprised of 34 patients who were diagnosed with MIS. The remaining 11 patients (average age, 19.3 ± 11.0 years; range, 8 to 16 years) with dyslexia from NODs comprised the NODs group. Males predominated both the MISs (72%) and NODs group (60%). The most common symptoms observed in the MIS group were difficulty in moving lines (85%), doubling (53%), and difficulty in bright conditions (27%), followed by letter reversal (26%), blurring (18%), repetition (12%), headache (9%), and floating (3%) (
Associated ocular diseases in the MIS and NODs group, were refractive error (79.4% and 72.7%, respectively), dry eye syndrome (29.4% and 18.1%, respectively), and exophoria (5.8% and 28.2%, respectively). In the MIS group, myopia and astigmatism were found in 23 patients, hyperopia and astigmatism were found in three patients and there was one patient with pure astigmatism. In the NODs group, refractive error was more common than exophoria and dry eye syndrome. ADHD was diagnosed in one patient in the MIS group and two patients in the NODs group (
MIS is considered to be a magnocellular system disorder that induces visual stress and distortion and the syndrome causes reading difficulties via hypertransmission of a specific light wave [
In our study, doubling and difficulty in moving lines were specific visual distortion symptoms observed only in MIS patients. Other symptoms of MIS, such as fatigue, eyestrain and headache, were also present in patients with refractive error, exophoria and dry eye syndrome. These observations underscore the importance of conducting a complete ophthalmic examination and directing treatment at associated ocular problems before prescribing colored filters to patients with MIS. While repetition has been considered to be a specific symptom of MIS, presently this symptom was present in both groups without any significant difference.
Dyslexia can be classified into primary (developmental) dyslexia and MIS. Primary dyslexia is a disorder of phonological processing due to abnormalities of the left hemisphere parieto-occipital lobe, which occurs in learning disabilities but can be improved with appropriate phonological training [
Dyslexia may appear in neuropsychiatric disorders; in particular, an association between ADHD and dyslexia has been reported [
In our study, doubling, difficulty in moving lines and bright conditions were specific visual symptoms observed in MIS. However, NODs also includes refractive error, dry eye syndrome and exophoria, which also cause dyslexia. Therefore, to diagnose MIS, an ophthalmologist should pay attention to these eye problems and try to correct them.
This paper is limited by the retrospective nature of the data collection, the lack of standardization of symptom recording and the asymmetric sample size. An effective diagnosis/test for developmental dyslexia has been and remains the goal of 30 years of extensive research in this field and the general consensus is that dyslexia cannot be diagnosed with just one test. Even though this study was focused on MIS, the improvement criteria for wearing color-tinted lenses should be validated [
In conclusion, doubling, difficulty in moving lines and bright conditions are specific visual symptoms observed in patients with MIS compared to nonspecific dyslexia from ophthalmologic disorders.
No potential conflict of interest relevant to this article was reported.
MISVIS filter used in this study.
Comparison of visual symptoms and signs between MIS and dyslexia from NODs
Values are presented as number or mean ± SD.
MIS = Meares-Irlen syndrome; NOD = nonspecific ophthalmologic disease; ADHD = attention deficit hyperactivity disorder.