By comparing the luminosity of a color with and without a filter (or between two different filters), the color can be estimated. This is the premise of monocular lenses and the SeeKey. In some US states, achromats can use a red filter while driving to determine the color of a traffic light. To alleviate photophobia stemming from hemeralopia, dark red or plum colored filters as either sunglasses or tinted contacts are very helpful at decreasing light sensitivity. To manage the low visual acuity that is typical of achromatopsia, achromats may use telescopic systems, specifically when driving, to increase the resolution of an object of interest. Epidemiology
Achromatopsia is a relatively uncommon disorder, with a prevalence of 1 in 30,000 people.However, on the small Micronesian atoll of Pingelap, approximately five percent of the atolls 3,000 inhabitants are affected. This is the result of a population bottleneck caused by a typhoon and ensuing famine in the 1770s, which killed all but about twenty islanders, including one who was heterozygous for achromatopsia.The people of this region have termed achromatopsia "maskun", which literally means "not see" in Pingelapese. This unusual population drew neurologist Oliver Sacks to the island for which he wrote his 1997 book, The Island of the Colorblind. Blue cone monochromacy
Blue cone monochromacy (BCM) is another genetic condition causing monochromacy. It mimics many of the symptoms of incomplete achromatopsia and before the discovery of its molecular biological basis was commonly referred to as x-linked achromatopsia, sex-linked achromatopsia or atypical achromatopsia.
Individuals with XLI appear at increased risk of developmental disorders such as autism and Attention Deficit Hyperactivity Disorder and some affected individuals exhibit mood problems  Mood problems in XLI appear to be most influenced by stigma or bullying associated with the skin condition, and by difficulties with treating the skin condition. Individuals with XLI can exhibit intellectual disability, although this is thought to be due to deletions encompassing neighboring genes (e.g. VCX) in addition to STS.Female carriers generally do not experience any of these problems but can have difficulty during childbirth, as the STS expressed in the placenta plays a role in normal labor. Female carriers may also be at slightly increased risk of developing mental health problems following childbirth  For these reasons carriers should ensure their obstetrician is aware of the condition. Genetics
The STS gene is located on the X chromosome at band Xp22.3. Thus, the syndrome is an X-linked condition, and it affects males and females differently. The 23rd pair of chromosomes is typically termed the "sex chromosomes". Females have two X chromosomes and males have one X and one Y chromosome. Therefore, in normal individuals, males carry a single copy of the STS gene and females carry two copies. This gene partially escapes X-inactivation and females normally express higher amounts of the STS enzyme than males.XLI can occur through new deletions or mutations of the STS gene but is more commonly inherited from a carrier mother.