Blue cone monochromacy (BCM) is an inherited eye disease that causes severe color blindness, poor visual acuity, nystagmus, hemeralopia, and photophobia due to the absence of functional red (L) and green (M) cone photoreceptor cells in the retina.

Blue cone monochromatism is an inherited vision disorder. In this condition, the light sensitive cells in the eye used for color vision (cones) are affected. There are three types of cones that respond to one of three colors: red, green, and blue.

Blue Cone Monochromacy (BCM) is a rare genetic retinal disorder estimated to affect 1 in 100,000 people. It is an inherited retinal degeneration (IRD) caused by mutations in the OPN1LW/OPN1MW gene cluster, encoding long (L)- and middle (M)-wavelength sensitive (i.e. red-green) opsins [38,39,41] of the cone photoreceptor cells in the retina.

This is a recessive X-linked disorder in which males are primarily affected. The carrier mother has normal color vision but carries the defective gene on one of her two X chromosomes and can expect on average that half of her male offspring will inherit blue cone monochromacy.

Blue cone monochromatism, (BCM), also known as X-linked incomplete achromatopsia, was initially described by Blackwell and Blackwell in 1957. monochromacy: a new color vision defect. J Optical Soc America 47:338–341). View our movie below, which provides an introduction to blue cone monochromatism.

Explore therapies, research, and support for Blue Cone Monochromacy with BCM Families Foundation. Together, making a brighter future possible.

There are three types of cones: Red cones, accounting for 64% of the total, also known as L-cones (maximally sensitive to long-wave light). Green cones, accounting for 32% of the total, also known as M-cones (maximally sensitive to medium-wave light).