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Preliminary observations concerning treatment of visual discomfort and associated perceptual distortion.
Wilkins, A.J., Milroy, R., Nimmo-Smith, I., Wright, A., Tyrrell, R., Holland, K., Martin, J., Bald, J., Yale, S., Miles, T. & Noakes, T.
Ophthalmic and Physiological Optics, 12, 257-262.
Year of publication:
A system for therapeutic precision tinting is described. Some individuals who are subject to perceptual distortion of text no longer perceive the distortion when the text has a particular colour. A simple colorimeter enables an observer to illuminate text with light of a particular chromaticity, varying first CIE 1976 hue angle (huv), then saturation (suv), and then luminance, to obtain a setting that maximises visual comfort and reduces any perceptual distortion. The colorimeter setting is then matched by a combination of tinted trial lenses. The combination uses only two dyes at a time from a selection of seven, unless a dark lens is required, when a third neutral (grey) dye is added. The subject observes both text and a normal scene when wearing tinted trial lenses. Various trial lenses are compared including those that match the colorimeter setting and others with similar hue angle. Spectacle lenses are then tinted so as to have a spectral transmission identical to that of the chosen combination of trial lenses. Certain patients with reading disorders, eye-strain, headaches or photosensitive epilepsy report benefit when wearing spectacles tinted according to the above techniques. The physiological basis for the therapeutic effects is uncertain, but may involve a selective impairment of luminance or colour-difference channels.