### condition | disability | blindness:

Color blindness
* Most color blindness is permanent , but some conditions can also lead to temporary color blindness
  - permanent, but some conditions can also lead to temporary color blindness.
  * Most colour blindness is heritable, usually as simple Mendelian inheritance. Most color blindness is permanent, but some conditions can also lead to temporary color blindness. During certain kinds of migraine, some people are unable to tell the difference between certain colors. As of 2009, there is no treatment or cure for permanent color blindness
  - result of a lack of one or more of the types of color cones in the retina
* color perception problem whose most common ailment red-green deficiency.
* comes as a result of a lack of one or more of the types of color receptors.
* congenital abnormality
* divisive code.
* is X-linked recessive.
* is an X-linked, recessive trait
  - absolute bar to employment
  - inaccurate term for a lack of perceptual sensitivity to certain colors
  - birth defects
* is caused by a defect in the color opsins on the X chromosome
  - defective color gene carried by the mother
  - determined genetically, is sex-linked, and occurs mostly in males
  - diseases
* is due to a recessive gene
  - the absence or impairment, of one or two cone systems
  - essentially a defect
  - fairly common, affecting about nine percent of all humans
  - for red or green
  - incurable
  - monitored through regular eye exams and visits to the healthcare provider
  - much more common in boys than in girls
  - rooted in the chromosomal differences between males and females
  - suppose to be extremely rare in girls
  - the partial or total inability to distinguish colors
  - usually self-diagnosed
  - very sensitive to changes in material
* lifelong condition.
* male dominant trait, but is carried by the female.
* misnomer because only a small percentage of people are unable to see any color.
* occurs in some children.
* recessive, X-linked trait
  - sex-linked trait in humans that is located on the X chromosome
+ Color blindness, Design changes: Diseases and disorders of the eye :: Genetic disorders
  * Color blindness is very sensitive to changes in material. A red-green color blind person may be unable to see the difference between colors on a map printed on paper. The same map on a computer screen or television may appear normally. In addition, some color blind people find it easier to tell the difference between colors on artificial materials, such as plastic or in acrylic paints, than on natural materials, such as paper or wood.

Legal blindness
* is blindness
  - defined in several ways
* manifests itself in a wide range of visual functioning.

### condition | disability | blindness:

Night blindness
* can cause problems with driving in the evening or at night.
* is disability
  - followed by tunnel vision
  - malnutrition
  - prevalent during pregnancy and lactation in rural Nepal
* is the first symptom that develops in many retinal diseases
  - inability of the eyes to quickly adjust to changes in light intensity
  - usually the first noticeable symptom, usually occurring during childhood
* makes vision difficult in dark or dimly lit places.
* serious problem on many atolls because of a lack of vitamin A in diets.

Permanent blindness
* can result from retinal detachment caused by scar tissue.
* is usually the result of even momentary eye contact with caustics.

River blindness
* Some river blindness is caused by nematodes.
* causes loss of sight, intense suffering, and premature death.
* is caused by parasitic worms that live just underneath the skin
  - when the worm involved burrows up under the skin and reaches the eyes
  - endemic in many parts of Africa and South America
  - infestation
  - spread by day-biting flies, and is the leading cause of blindness worldwide
* slow acting disease, which ends in complete blindness.