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Portrait of a religious donor wearing hair sticks decorated with gold and jade, 983 AD. A hair stick (also hairstick) is a device, long and thin, usually between five and nine inches (13 cm to 23 cm) long, used to hold a person's hair bun or similar hairstyle in place. It may be straight or tapered; it is often pointed to ease insertion.
Males are more likely to inherit red–green color blindness than females, because the genes for the relevant opsins are on the X chromosome. [1] Screening for congenital red–green color blindness is typically performed with the Ishihara or similar color vision test. [1] It is a lifelong condition, and has no known cure or treatment. [1]
Color blindness may also present itself as a symptom of degenerative diseases of the eye, such as cataract and age-related macular degeneration, and as part of the retinal damage caused by diabetes. Vitamin A deficiency may also cause color blindness. [47] Color blindness may be a side effect of prescription drug use.
These include issues around the governance of the therapy, whether treatment should be available only to those who can afford it, and whether the availability of treatment creates a stigma for those with color blindness. Given the large number of people with color blindness, there is also the question of whether color blindness is a disorder. [16]
A swordstick or cane-sword is a cane containing a hidden blade or sword. The term is typically used to describe European weapons from around the 18th century. But similar devices have been used throughout history, notably the Roman dolon , [ 1 ] the Japanese shikomizue and the Indian gupti .
Cerebral achromatopsia is a form of acquired color blindness that is caused by damage to the cerebral cortex. Damage is most commonly localized to visual area V4 of the visual cortex (the major part of the colour center ), which receives information from the parvocellular pathway involved in color processing.
While the right age to let children go unsupervised tends to be a source of debate, many experts agree that children under 12 should go trick-or-treating with an adult.
Monochromacy (from Greek mono, meaning "one" and chromo, meaning "color") is the ability of organisms to perceive only light intensity without respect to spectral composition. Organisms with monochromacy lack color vision and can only see in shades of grey ranging from black to white. Organisms with monochromacy are called monochromats.