This article possibly contains original research .(April 2013) |
Irlen spectral filters or Irlen lenses are coloured overlay filters or tinted lenses crafted specifically for the wearer and worn as glasses or contact lenses. They are intended to help people with the supposed perceptual processing difficulty known as Irlen syndrome, also known as scotopic sensitivity syndrome or visual stress, in which sensitivity to specific wavelengths of light provokes difficulty and discomfort when performing visually intensive activities such as reading. The existence of Irlen syndrome is controversial. [1] The Royal Australian and New Zealand College of Ophthalmologists (RANZCO) came out strongly against Irlen syndrome, saying there was no evidence the condition existed or the treatment of reading difficulties with Irlen lenses worked. [2] However, there is a small body of research supporting the use of colour to alleviate the symptoms associated with Irlen syndrome. [3] [4] [5] [6] [7] [8] [9]
Scotopic sensitivity syndrome is said to be a visual-perceptual defect related to difficulties[ vague ] with light source, glare, luminance, wavelength, and contrast. According to Irlen, these difficulties lead to reading problems, eye strain, headaches, migraines, and other physical difficulties that can be alleviated by the use of person specific tinted lenses, known as Irlen spectral filters, worn as glasses or contact lenses.
The syndrome has six characteristics:
Scotopic sensitivity syndrome is diagnosed by interviewing the client and by observing responses to certain visual tasks such as interpreting geometric figures and reading. [10]
The idea of page based distortion was initially suggested in 1980 by Olive Meares, [11] to improve the reading ability of people with a learning disability, specifically a certain type of dyslexia. Later this was taken further by psychologist Helen Irlen. The proposition by Irlen was made at the Annual Meeting of the American Psychological Association in 1983. At that time, there was little research made on the effect of tinted lenses. Irlen gained notable publicity demonstrating the efficacy of her method on television. Tinted lenses became a commercial success, and testing and prescribing centers were opened throughout USA. [12]
Diagnosis of Irlen Syndrome and treatment with Irlen Spectral Filters has been reviewed by the USA Medical Board,[ which? ] and has been determined as not the practice of medicine; it has also been reviewed by various USA Boards of Optometry[ which? ] and has been found to be inconclusive and not to be the practice of optometry. Binocular and accommodative anomalies may occur in conjunction with the syndrome, but are not considered to be the underlying physiological basis of the condition. [13] [14]
According to Irlen, the lenses are supposedly used to treat a wide variety of problems that are associated with light sensitivity, discomfort and distortions, including head injury, concussion, whiplash, perceptual problems, neurologic impairment, memory loss, language deficits, headaches and migraine, autoimmune disease, fibromyalgia, macular degeneration, cataracts, retinitis pigmentosa, complications from an eye operation, depression, chronic anxiety and others. [1] She has also claimed that a treatment for scotopic sensitivity syndrome could help a number of incarcerated individuals and delinquent children. [1]
The Irlen method has been criticised for being put to the market prior to serious research. [1] According to Helveston, the scotopic sensitivity syndrome and its treatment has, as a phenomenon, resulted in classic group behaviour and has the characteristics of a fad with a charismatic personality as a leader and the supporting evidence being mostly anecdotal—even though those with visual stress are spread around the world, mostly don't know each other, and have no interest in Helen Irlen, all of which conditions would need to be met to fulfill the criteria of group dynamics. [1] A 2002 study by Professor Arnold Wilkins at Essex University, though, indicates that there may be some benefit for reading difficulties [15] [ citation needed ], and also for people with migraines. [16]
Migraine is a genetically influenced complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea and light and sound sensitivity. Other characterizing symptoms may include nausea, vomiting, cognitive dysfunction, allodynia, and dizziness. Exacerbation of headache symptoms during physical activity is another distinguishing feature. Up to one-third of migraine sufferers experience aura: a premonitory period of sensory disturbance widely accepted to be caused by cortical spreading depression at the onset of a migraine attack. Although primarily considered to be a headache disorder, migraine is highly heterogenous neurological disease in its clinical presentation and is better thought of as a spectrum disease rather than a distinct clinical entity. Disease burden can range from episodic discrete attacks to chronic disease.
Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include headaches and eye strain. Severe near-sightedness is associated with an increased risk of retinal detachment, cataracts, and glaucoma.
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia. The term photophobia comes from the Greek φῶς (phōs), meaning "light", and φόβος (phóbos), meaning "fear".
Amaurosis fugax is a painless temporary loss of vision in one or both eyes.
Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or coloured dots across the whole visual field. Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches. The condition is typically always present and has no known cure, as viable treatments are still under research. Astigmatism, although not presumed connected to these visual disturbances, is a common comorbidity. As well, migraine and tinnitus are common comorbidities which are both associated with a more severe presentation of the syndrome. TMJ may also be a common comorbidity.
Triptans are a family of tryptamine-based drugs used as abortive medication in the treatment of migraines and cluster headaches. This drug class was first commercially introduced in the 1990s. While effective at treating individual headaches, they do not provide preventive treatment and are not considered a cure. They are not effective for the treatment of tension–type headache, except in persons who also experience migraines. Triptans do not relieve other kinds of pain.
Refractive error, also known as refraction error, is a problem with focusing light accurately on the retina due to the shape of the eye and or cornea. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.
Bálint's syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole (simultanagnosia), difficulty in fixating the eyes, and inability to move the hand to a specific object by using vision. It was named in 1909 for the Austro-Hungarian neurologist and psychiatrist Rezső Bálint who first identified it.
Ocular dominance, sometimes called eye preference or eyedness, is the tendency to prefer visual input from one eye to the other. It is somewhat analogous to the laterality of right- or left-handedness; however, the side of the dominant eye and the dominant hand do not always match. This is because both hemispheres control both eyes, but each one takes charge of a different half of the field of vision, and therefore a different half of both retinas. There is thus no direct analogy between "handedness" and "eyedness" as lateral phenomena.
Irlen syndrome, also referred to as scotopic sensitivity syndrome (SSS), visual stress, or Meares–Irlen syndrome, is a light-based visual processing disorder. Many mainstream professionals are skeptical of the concept; however, current neuroscience research has successfully documented differences in brain function among this population versus those without the condition. Early research on Irlen syndrome produced mixed results; however, the overwhelming majority of studies conducted over the last 40 years have documented the benefits of using precision-tinted colored lenses to address a variety of related symptomology, including: reduction in physical symptoms that include headaches, migraines, eye strain, fatigue, and light sensitivity; and improved functioning and success in both academia and the workplace.
Computer vision syndrome (CVS) is a condition resulting from focusing the eyes on a computer or other display device for protracted, uninterrupted periods of time and the eye's muscles being unable to recover from the constant tension required to maintain focus on a close object. Some symptoms of CVS include headaches, blurred vision, neck pain, fatigue, eye strain, dry eyes, irritated eyes, double vision, vertigo/dizziness, polyopia, and difficulty refocusing the eyes. These symptoms can be further aggravated by improper lighting conditions or air moving past the eyes.
Vision therapy (VT), or behavioral optometry, is an umbrella term for alternative medicine treatments using eye exercises, based around the scientific evidences that vision problems are the true underlying cause of learning difficulties, particularly in children. Vision therapy has not been shown to be effective according to modern evidence-based medicine. Most claims—for example that the therapy can address neurological, educational, and spatial difficulties—lack supporting evidence. Neither the American Academy of Pediatrics nor the American Academy of Ophthalmology support the use of vision therapy.
A reading disability is a condition in which a person displays difficulty reading. Examples of reading disabilities include: developmental dyslexia, alexia, and hyperlexia.
Mesopic vision, sometimes also called twilight vision, is a combination of photopic and scotopic vision under low-light conditions. Mesopic levels range approximately from 0.01 to 3.0 cd/m2 in luminance. Most nighttime outdoor and street lighting conditions are in the mesopic range.
Fixation disparity is a tendency of the eyes to drift in the direction of the heterophoria. While the heterophoria refers to a fusion-free vergence state, the fixation disparity refers to a small misalignment of the visual axes when both eyes are open in an observer with normal fusion and binocular vision. The misalignment may be vertical, horizontal or both. The misalignment is much smaller than that of strabismus. While strabismus prevents binocular vision, fixation disparity keeps binocular vision, however it may reduce a patient's level of stereopsis. A patient may or may not have fixation disparity and a patient may have a different fixation disparity at distance than near. Observers with a fixation disparity are more likely to report eye strain in demanding visual tasks; therefore, tests of fixation disparity belong to the diagnostic tools used by eye care professionals: remediation includes vision therapy, prism eye glasses, or visual ergonomics at the workplace.
Like Colour To The Blind (1996) is the third in a series of four autobiographical works by internationally bestselling autistic author Donna Williams. Once published in the US using the American spelling 'color', it is now published worldwide by Jessica Kingsley Publishers using the UK spelling 'colour'. It has been published in several languages worldwide.
Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details.
Dyslexia is a reading disorder wherein an individual experiences trouble with reading. Individuals with dyslexia have normal levels of intelligence but can exhibit difficulties with spelling, reading fluency, pronunciation, "sounding out" words, writing out words, and reading comprehension. The neurological nature and underlying causes of dyslexia are an active area of research. However, some experts believe that the distinction of dyslexia as a separate reading disorder and therefore recognized disability is a topic of some controversy.
Color blind glasses or color correcting lenses are light filters, usually in the form of glasses or contact lenses, that attempt to alleviate color blindness, by bringing deficient color vision closer to normal color vision or to make certain color tasks easier to accomplish. Despite viral status, the academic literature is generally skeptical of the efficacy of color correcting lenses.
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