The use of tinted lenses in glasses and coloured overlay sheets has been prescribed by many doctors; however, the efficacy of such treatment is questionable. It has been felt to be efficient treatment by some, and inappropriate by others, because more conventional treatments are sometimes more appropriate.
The College of Optometry (UK) has specified guidelines for optometrists who use the colorimeter system. A society for colored lens prescribers has been established to provide a list of eye-care practitioners with expertise in the provision of colored lenses for the treatment of visual stress.
The Promethean Trust, a Norwich-based charity for dyslexic children, has found that the use of a cursor has eliminated the need for colored overlays or lenses. The cursor is simply a piece of card or plastic, approximately the size of a business card, with a notch cut out of one corner. The reader (or the remedial teacher) uses this to track print from left to right, and at the same time the card prevents the eyes from wandering ahead. Although no formal research has been conducted, it is likely that most cases of visual confusion result from the eyes moving in mini-saccades when the reader encounters an unfamiliar word. This occurs as the reader subconsciously tries to scramble letters to achieve a 'fit' with a familiar word. This creates the subjective impression that the letters 'won't stay still'.
Irlen Method
The Irlen Method is a controversial system that is intended to improve reading difficulties associated with scotopic sensitivity syndrome using tinted lenses and overlays.
Irlen Screener
"Irlen Screeners are certified to administer the first testing session and determine whether an individual will benefit from further evaluation for Irlen Spectral Filters."
Irlen Diagnosticians
"Irlen Diagnosticians are certified to administer both testing sessions. During the initial testing session, an individual is screened to determine whether wearing Irlen Spectral Filters will make a difference and the amount of improvement for reading and other academic activities. In addition, during this session 12 other areas will be evaluated and recommendations made. Only Irlen Diagnosticians are certified to test and determine your customized spectral filter worn as Irlen glasses or contact lenses and conduct yearly rechecks."
Intuitive Colorimeter
Developed by Arnold Wilkins, Ph.D., University of Essex, England, an alternative system for the identification of tint to reduce symptoms.