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Correcting Scotopic Sensitivity
In 1983 American psychologist Helen Irlen discovered that light sensitivity could cause reading difficulties and perceptual problems. Through experimentation, she found that some people benefited from the use of colored overlays that seem to work by filtering out light rays that cause distortions to print. Since then, Helen has developed an effective protocol for identifying this disability, and has designed a standardized set of procedures to determine the correct color selection that will provide the greatest relief. Although IS cannot be cured, it can be managed. There are two ways to correct it:
- Colored transparencies (overlays) to improve reading on the printed page
- Tinted glasses to improve both reading and visual perception of the environment
Transparencies. Irlen Transparencies or overlays are placed over printed text to reduce perceptual stress while reading. A colored overlay interrupts wavelengths of light and reduces the contrast between black and white and the dominance of the white background. The color depends upon each person's unique visual-perceptual system, and is determined through a series of standardized procedures developed by Helen Irlen. Twenty-seven different color combinations are used to determine the color or colors that will provide the greatest relief.
Irlen Filters (Tinted Lenses). In addition to reading problems, people with Irlen Syndrome often have difficulty functioning in their surroundings. They may suffer from strain, fatigue, and even migraine headaches under fluorescent lighting. They may be bothered by sunlight, or by the glare of headlights while driving at night. They may have depth perception problems that make navigating stairs and getting on and off escalators extremely difficult. Lenses tinted with the correct colors can alleviate these problems. Lenses can either be prescription or non-prescription, and are tinted by means of a patented process. To determine the correct colors for tinting lenses, eighty-five different colors are used that combined, can make an infinite number of colors. Whereas standard tinted lenses provided by optometric firms are only one color, Irlen Filters contain multiple layers of colors.
What the filters and lenses do
For sufferers of Irlen Syndrome, the full spectrum of light causes distortions with print and in the environment. The filters and overlays interrupt and filter out certain wavelengths of light so that the brain can process visual information more efficiently. Distortions and discomfort are immediately alleviated. Extensive testing is required to determine the exact color or combination of colors that will be most effective for each individual.
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