The color deficient often seek visual aids to mitigate their color confusions. The most popular aids are red high-pass filters worn monocularly. Any benefit offered by such aids is limited to specific tasks and/or hue regions and may be negated by deleterious side- effects, including reduced luminance and visual acuity, induced visual distortions, altered stereopsis, and impaired depth perception. Different types of filters, taking into account advances in the molecular genetics of color vision and in coating technology, may offer greater advantages. (C) 2000 John Wiley & Sons, Inc.