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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Patients who think they have a visual-perception dysfunction known as scotopic sensitivity-Irlen syndrome have trouble reading and may experience almost-constant headaches. Some find they are helped by coloured filters developed by a California researcher, Helen Irlen, who published a book on the subject called Reading by the Colors. Although Irlen has been criticized for not publishing scientific proof of the validity of her theories, her techniques have found some support, including some within the medical community.
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PMID:Use of filters to treat visual-perception problem creates adherents and sceptics. 763 13

A recent double-masked placebo-controlled trial has confirmed that some children experience a reduction in symptoms of eyestrain and headache when they read through individually prescribed coloured filters and has shown that this benefit cannot be solely attributed to a placebo effect. People who are helped by coloured filters in this way have been described as having "Meares-Irlen syndrome'. We investigated the mechanism of this benefit by studying the optometric and visual perceptual characteristics of the children in the double-masked study. This population had normal refractive errors and heterophorias (none of the subjects had strabismus). They demonstrated slightly, but significantly, reduced amplitudes of accommodation and vergence and poor stereo-acuity. However, these factors seemed to be correlates of Meares-Irlen syndrome rather than the underlying cause. Pattern glare, a sensitivity to striped patterns (e.g. lines of text), was prevalent in our sample and was significantly associated with the subjects' symptoms. The spatial contrast sensitivity function was normal.
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PMID:A preliminary investigation into the aetiology of Meares-Irlen syndrome. 879 97

Meares-Irlen syndrome is characterised by symptoms of eye strain, headaches and visual perceptual distortions when viewing text. The symptoms are alleviated with individually prescribed coloured filters, such as precision tinted lenses. Meares-Irlen syndrome, and the related condition of visual stress, are likely to result from hyperexcitability of the visual cortex, which can also occur in migraine. The symptoms of Meares-Irlen syndrome and visual stress are non-specific and the condition needs to be differentially diagnosed from other optometric conditions, such as refractive error, binocular vision anomalies, and accommodative anomalies. Three case reports are described of patients who consulted the author with suspected Meares-Irlen syndrome but were found to have other causes for their symptoms: posterior sub-capsular cataract, high uncorrected astigmatism, and decompensated convergence weakness exophoria. These cases highlight the need for professional eye care for people with suspected Meares-Irlen syndrome. Although this advice is stressed in literature on the well-established MRC/Wilkins Intuitive Colorimeter system, it is not always stressed in literature about other systems. This may be a cause for concern.
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PMID:The need for optometric investigation in suspected Meares-Irlen syndrome or visual stress. 1595 22

Pattern glare is characterised by symptoms of visual perceptual distortions and visual stress on viewing striped patterns. People with migraine or Meares-Irlen syndrome (visual stress) are especially prone to pattern glare. The literature on pattern glare is reviewed, and the goal of this study was to develop clinical norms for the Wilkins and Evans Pattern Glare Test. This comprises three test plates of square wave patterns of spatial frequency 0.5, 3 and 12 cycles per degree (cpd). Patients are shown the 0.5 cpd grating and the number of distortions that are reported in response to a list of questions is recorded. This is repeated for the other patterns. People who are prone to pattern glare experience visual perceptual distortions on viewing the 3 cpd grating, and pattern glare can be quantified as either the sum of distortions reported with the 3 cpd pattern or as the difference between the number of distortions with the 3 and 12 cpd gratings, the '3-12 cpd difference'. In study 1, 100 patients consulting an optometrist performed the Pattern Glare Test and the 95th percentile of responses was calculated as the limit of the normal range. The normal range for the number of distortions was found to be <4 on the 3 cpd grating and <2 for the 3-12 cpd difference. Pattern glare was similar in both genders but decreased with age. In study 2, 30 additional participants were given the test in the reverse of the usual testing order and were compared with a sub-group from study 1, matched for age and gender. Participants experienced more distortions with the 12 cpd grating if it was presented after the 3 cpd grating. However, the order did not influence the two key measures of pattern glare. In study 3, 30 further participants who reported a medical diagnosis of migraine were compared with a sub-group of the participants in study 1 who did not report migraine or frequent headaches, matched for age and gender. The migraine group reported more symptoms on viewing all gratings, particularly the 3 cpd grating. The only variable to be significantly different between the groups was the 3-12 cpd difference. In conclusion, people have an abnormal degree of pattern glare if they have a Pattern Glare Test score of >3 on the 3 cpd grating or a score of >1 on the 3-12 cpd difference. The literature suggests that these people are likely to have visual stress in everyday life and may therefore benefit from interventions designed to alleviate visual stress, such as precision tinted lenses.
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PMID:The Pattern Glare Test: a review and determination of normative values. 1856 84