Which color vision deficiency can be present without genetic inheritance?

Acquired defects in color vision can arise due to various factors that do not involve genetic inheritance. Conditions such as disease, medication side effects, or ocular issues can lead to changes in an individual's color vision, resulting in an acquired color vision deficiency. For example, retinitis pigmentosa, optic neuritis, or exposure to certain chemicals can cause a shift in color perception, thereby leading to a temporary or permanent defect in color vision.

In contrast, the other color vision deficiencies, such as protanopia, deuteranopia, and tritanopia, are specifically linked to genetic abnormalities that affect the cones in the retina responsible for color detection. These deficiencies are inherited conditions, often passed down through family genetics, leading to the inability to perceive specific colors accurately.

Thus, the distinction lies in the underlying cause; acquired defects can develop later in life through environmental or health-related influences, while the others are purely inherited genetic conditions.