| Blue cone monochromacy | |
|---|---|
| Other names | X-linked achromatopsia |
| Specialty | Ophthalmology |
| Symptoms | poor ability or inability to distinguish colours, poor visual acuity, nystagmus, hemeralopia |
| Usual onset | congenital |
| Differential diagnosis | incomplete achromatopsia |
| Treatment | dark lenses |
| Frequency | 1 in 100,000 |
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. BCM is a recessive X-linked disease and almost exclusively affects XY karyotypes.