tritanopie

Tritanopie, also spelled tritanopia, is a rare congenital color vision deficiency characterized by a reduced or absent ability to distinguish blue from yellow. This condition results from dysfunction or absence of the short-wavelength sensitive cones (S-cones) in the retina. People with tritanopie typically retain normal discrimination along red–green pathways, but their perception of the blue–yellow axis is unreliable, and many blues may resemble greens while yellows may appear violet or pink.

Causes and inheritance: Most cases are inherited from mutations affecting S-cone function. Tritanopie can also be acquired later in life due to retinal disease, optic neuropathy, or certain medications or injuries that damage the S-cone pathway. It is far rarer than red-green color deficiencies.

Diagnosis and management: Diagnosis uses specialized color vision tests that assess blue–yellow discrimination, such as the Hardy–Rand–Rittler (HRR) pseudoisochromatic plates; anomaloscope testing can also be used in some settings. There is no cure. Management focuses on education and adjustment, including high-contrast signage, color-agnostic labeling, and reliance on noncolor cues (shape, texture, position) in daily activities and work.

Epidemiology and impact: The prevalence of tritanopie is very low, much rarer than other common color vision deficiencies. It can affect certain occupations or tasks that depend on blue–yellow cues, but individuals usually adapt with appropriate accommodations.

See also: color vision deficiency; tritanomaly; S-cone color defects.