Contemporary eye care includes qualitative and quantitative assessment of this important measure of visual function. Acquired color deficiencies are commonly S-cone (blue-yellow) type, but may also affect L- and M-cones. Acquired deficiencies are typically gender neutral and become more common with age, yet may affect up to 15%* of the general population.
This important but often overlooked clinical sign may be caused by retinal,macular, optic nerve, trauma or neurological disorders, in addition to cataracts and high-risk meds, as well as hundreds of common drugs and substances**.
Testing for acquired color vision deficiencies may be one of the most underutilized measures of functional vision. Commonly used color vision tests historically (such as printed pseudo-isochromatic, “Ishihara plates”, designed more than a century ago), may only test L and M-cone deficiencies, completely missing all S-cone (blue) deficiencies as well as being not quantitative. Genetic color vision deficiencies, most commonly affect males as a sex-linked trait and most commonly affect the L or M-cones.
*Rayman, R., et al. Rayman’s Clinical Aviation Medicine. Castle Connelly. 2013.
**Fraunfelder, Fraunfelder, Chambers. Clinical Ocular Toxicology. Sanders Elsevier, 2008: 320. Clinical Ocular Toxicology, Substances and Pharmaceutical Agents that can Cause Color Vision Defects.
CCT-HD is based upon the principle of stimulating individual cone type populations, L-cone (long wavelength), M-cone (medium), and S-cone (short).
Fundamentals of Cone-isolation, Contrast Sensitivity
CCT-HD is based upon the principle of stimulating individual cone type populations, L-cone (long wavelength), M-cone (medium), and S-cone (short). Each cone population has offset peak sensitivities and broad ranges of sensitivities. Although L-cones are often referred to as “red”, M-cones as “green”, and S-cones as “blue”, peak sensitivity wavelengths of the cone populations are colors not fitting these descriptions.
CCT HD tunes the calibrated stimulus color composition to simultaneously maximize the response of a targeted cone population, minimize, as negligible, the response of non-targeted cones, and neutralize achromatic (brightness) cues.