Colour Vision Defects

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Abstract Normal colour vision refers to the form of trichromatic colour vision shared by most individuals. It is mediated by three types of retinal cone photoreceptors, short‐ (S), medium‐ (M) and long‐ (L) wavelength‐sensitive. Colour vision defects can either be inherited as the consequence of genetic defects that affect the function of one or more cone type, or they can be acquired through exposure to neurotoxins or as secondary effects of systemic or ocular diseases. Among individuals with colour vision deficiency, there is tremendous variation in the capacity for colour vision, ranging from no colour vision to nearly normal. Viral‐mediated gene therapy for ocular diseases has been an area of intense investigation over the last decade. Because genetic mutations underlying colour vision deficiencies have been identified, gene therapy may be a viable option for curing various forms of colour blindness in the future. Key Concepts: Normal colour vision requires three classes of cone photoreceptor in the retina: short‐, medium‐ and long‐wavelength sensitive. The hallmark feature of colour vision defects is a reduction in the number of different colours that can be distinguished from each other. Colour vision defects can either be inherited or they can be acquired secondary to disease or through exposure to certain drugs or neurotoxins. Mutations and rearrangements in the genes encoding the short‐, medium‐ and long‐wavelength sensitive photopigments are responsible for inherited colour vision deficiencies. Gene therapy has been successfully used to treat colour blindness in animal models and these experiments pave the way towards cures for colour blindness in humans.