Blue cone monochromatism

Blue-cone monochromaticity (BCM for short) manifests in the patient through various visual impairments, including impaired visual acuity, severely disturbed color vision, photophobia, and nystagmus. These symptoms are triggered by a dysfunction of the red and green cones, caused by a genetical mutation.

The disease is already noticeable in early infancy and is more common in boys than girls.

Only the function of the rods and the blue cones remain, which leads to visual limitations. However, the above-mentioned nystagmus diminishes in the course of the disease.

The cause is a mutation in the red and green opsin gene clusters OPN1LW and OPN1MW (Xq28). The disease is inherited as an X-linked recessive trait.