Irlen syndrome: systematic review and level of evidence analysis / Síndrome de Irlen: revisão sistemática e análise do nível de evidência

ABSTRACT Background: Scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability due to poor color matching and distorted graphic images. Individuals with this syndrome are considered slow, ineffective readers with low comprehension and visual fatigue. It is still uncertain whether the disease pathophysiology is an independent entity or part of the dyslexia spectrum. Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients' reading performance. However, no evidence of treatment effectiveness has been achieved. Objective: The aim of the present study was to obtain evidence about IS etiology, diagnosis and intervention efficacy. Methods: A systematic review was performed covering the available studies on IS, assessing the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes. Results: The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness. Conclusion: The syndrome as described, as well as its treatments, require further strong evidence.

RESUMO Background: A síndrome da sensibilidade escotópica, posteriormente denominada síndrome de Meares-Irlen ou simplesmente síndrome de Irlen (SI), foi descrita como indivíduos com sintomas de baixa capacidade de leitura devido à combinação de cores e distorções nas imagens. Indivíduos com essa síndrome podem apresentar leitura lenta e ineficaz, com baixo nível de compreensão e fadiga visual. A fisiopatologia da doença ainda é incerta como uma entidade independente ou como parte do espectro da dislexia. No entanto, tratamentos com lentes e filtros coloridos foram propostos com o objetivo de aliviar o efeito do contraste luminoso e melhorar o desempenho de leitura dos pacientes. Outrossim, nenhuma evidência de eficácia do tratamento foi alcançada. Objetivos: Obter evidências sobre a etiologia, eficácia diagnóstica e intervenção da SI. Métodos: Foi realizada uma revisão sistemática, cobrindo os estudos disponíveis sobre a SI, avaliando os dados disponíveis de acordo com seu nível de evidência, com foco em ferramentas de diagnóstico, intervenções propostas e desfechos relacionados. Resultados: Os dados mostram alta heterogeneidade, falta de evidência sobre a existência da SI e eficácia do tratamento. Conclusões: A síndrome descrita e seus tratamentos exigem evidências mais robustas.

Functional Magnetic Resonance Imaging Findings in Meares-Irlen Syndrome: A Pilot Sudy

PURPOSE: To investigate patterns of functional magnetic resonance imaging (fMRI) activation during sentence reading before and after wearing color-tinted lenses. METHODS: A total of 15 Meares-Irlen syndrome patients with a mean age of 23.4 years (range, 13 to 42 years) with no history of neurological or psychiatric disorders were scanned using a 3T MR scanner (Siemens, Tim-Trio, Germany). Each patient underwent two sessions of fMRI imaging (before and after MISViS color-tinted lens application). The fMRI paradigm included a block design of 20 seconds of rest (cross), 20 seconds of activation (sentence reading), and ten blocks (a total of 200 echo-planar image volumes) repeated for each session. Data preprocessing and analyses were performed using the SPM8 software package. RESULTS: The reading speed of patients improved more than 20% while wearing the selected lenses. When compared to the before-lens session, the after-lens session identified significant regions of activation in the left middle and superior temporal gyri (paired t-test; maximal z score, 5.38; Montreal Neurological Institute coordinate, -60 / -39 / 0; threshold at p < 0.05; corrected for multiple comparisons using family-wise error). No region of activation at the same threshold was found in the before-lens session as compared to the after-lens session. CONCLUSIONS: In the current study, we confirmed activation in the left middle and superior temporal gyri during sentence reading after wearing color-tinted lenses. These results could explain the effectiveness of color-tinted lenses in patients with Meares-Irlen syndrome.

Specific Visual Symptoms and Signs of Meares-Irlen Syndrome in Korean

PURPOSE: To discriminate the visual symptoms and signs of Meares-Irlen syndrome (MIS) and nonspecific dyslexia from other ophthalmologic diseases (NODs). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

The Effect of Colored Filters in Patients with Meares-Irlen Syndrome

PURPOSE: To evaluate the benefit of colored filters in Meares-Irlen Syndrome patients with reading difficulties. METHODS: Twenty-five patients were selected through a brief questionnaire aimed to determine symptoms of eyestrain or visual distortion after thorough eye examinations. The cutoff value of the questionnaire was 2.13. The rates of Korean reading and writing were measured using the RWSM (Reading Writing Speed Meter) test with and without the use of colored filters. Two months after wearing the individually prescribed colored filters, a questionnaire on the patient's subjective satisfaction with the colored filters were completed and evaluated. RESULTS: The blue (n = 8, 32%) and gray (n = 4, 16%) colors were the most frequently selected filters. The mean score of the questionnaire on reading difficulties was 2.72. The mean reading rate improved from 82.72 wpm (words per minute) to 101.84 wpm with the colored filters, a statistically significant change (p = 0.019). The mean writing rate did not improve. The overall satisfaction score with the colored lenses was 3.6, with the highest score given to ease of reading (4.08) and the lowest to writing (2.92). CONCLUSIONS: In cases of reading difficulty, colored filters were effective for alleviating visual symptoms and improving reading speed. It is important to achieve an adequate understanding of the specific symptoms of Meares-Irlen Syndrome and to perform a thorough eye examination to differentiate this from other ocular disorders.

Clinical Characteristics of Patients With Dyslexia in Korea : Correlation With Meares-Irlen Syndrome

PURPOSE: To evaluate the main symptoms and associated ocular diseases in patients with dyslexia (reading difficulty) in Korean subjects. METHODS: A total of 16 patients were enrolled in the present study. Eleven of the patients with Meares-Irlen syndrome whose symptoms improved with tinted lenses comprised Group 1. The other 5 patients whose reading difficulty improved with other ocular therapy and did not require tinted lenses comprised Group 2. The main symptoms causing dyslexia and associated ocular diseases were evaluated. RESULTS: The mean age was 18.9 +/- 8.9 years in Group 1, and 20.4 +/- 12.3 years in Group 2. In Group 1, the most common symptoms while reading were doubling (72%), difficulty to move lines (46%), letter reversal (27%) and blurring or ocular pain (27%). On the other hand, blurring (100%) with fatigue or pain (20%) was documented in Group 2. The associated ocular diseases in Group 1 and Group 2 were refractive error (63% and 20%), dry eye (18% and 60%), and exophoria (18% and 60%), respectively. CONCLUSIONS: Doubling and difficulty to move lines while reading were the main specific symptoms in Meares-Irlen syndrome in the present study. Refractive error, dry eye, and exophoria were commonly associated in patients with dyslexia.