Daltonism

Description:

Color-blindness is an abnormal state which is characterized by inability accurately to distinguish different color ranges. People with daltonism not blind people, they are inclined to see colors in the limited range of shades.
Normal color sight assumes involvement in process of specialized receptor cells which are called to is called flasks.  They are located in an eye retina. There are three types of flasks: red, blue and green which allow people to see a wide range of flowers. Deficit of any of types of flasks will lead to disturbance of color sight.
There are three main options of color-blindness. Red/green color-blindness is the most widespread shortcoming, arising at 8% of men, residents of the Caucasus and 0,5% of the women living in the same area. Prevalence depends on culture.
Blue color-blindness is inability to distinguish blue and yellow colors which seem the patient as white or gray. It is quite rare pathology which has identical prevalence at men and women. Small children often confuse blue and green colors, however at mature age this defect becomes less expressed.  Inability to distinguish blue color often is shown at people who have somatopathies, such as diseases of a liver or a diabetes mellitus.
Full inability to distinguish colors (achromatopsia) -  extremely rare pathology. People with achromatopsia look at the world in shades of gray. They often have low visual acuity also are extremely sensitive to light (the photophobia is observed) that leads to squint.

Daltonism reasons:

Red/green and blue color-blindness is shown at pathology at least in two different genes. Most of the persons having daltonism -  men. Women are carriers of a pathological gene, but usually are not ill. It means that X-chromosome is the place of localization of the pathological genes which are responsible for development of daltonism. Very seldom women who suffer from red / green or blue color-blindness meet, however such cases indicate existence of other gene which is the reason of daltonism.  Achromatopsia, or full inability to distinguish colors, is an autosomal and recessive disease of a retina. Thus, both parents have according to one copy of the changed gene, but have no this disease. In 1997 a gene of achromatopsia was it is found in the 2nd chromosome.

Daltonism symptoms:

Inability it is correct to define color is the only sign of color-blindness. People with color-blindness can distinguish colors if visually they are compared.  Nevertheless, to most of them of patients with daltonism exact  determination of color represents difficulty. Most of people with any disturbances of color sight learns colors, as well as other small children. These people often reach teenage age when color deficit comes to light.  

Color-blindness sometimes has the acquired character. The list of chronic diseases which can result in color-blindness  includes in itself Alzheimer's disease, a diabetes mellitus, glaucoma, leukemia, liver diseases, an alcoholism, a macula lutea degeneration, multiple sclerosis, Parkinson's disease, a sickemia and a pigmental retinitis. Blows which injure a retina or influence specific areas of a brain, an eye can result in color-blindness. Some drugs, such as the antibiotics, barbiturates, antitubercular drugs, antihypertensive drugs and some drugs used for treatment of nervous breakdowns and psychological problems can result in color-blindness. Industrial and ecological chemicals, such as carbon monoxide, carbon sulfur, fertilizers, styrene, and some substances containing lead  can lead to loss of color sight.

Diagnosis:

At the first suspicion of daltonism it is necessary to consult with the ophthalmologist.
There are several available tests for identification of the problems connected with color sight. The most often used American Optical/Hardy,  Rand and Ritter Pseudoisochromatic the test. It consists of several disks  filled with color points of various sizes and flowers. The person with normal color sight, looking at the test sees a number sequence among points. The color-blind person is not able to distinguish numbers.
The test Ishihara consists of eight plates similar to American Optical Pseudoisochromatic  - the test. To the patient with disturbance of color sight  suggest to find numbers between various color points on each test plate. In such a way it is possible to distinguish  red / green and blue options of color-blindness.
The third analytical test Titmus is capable to define red / green deficit of color sight, however its accuracy concedes to the above tests.

Treatment of daltonism:

As of this moment there is no effective treatment of daltonism. Inheritance  of daltonism  cannot be also prevented. In cases of some types of the acquired color deficit if the reason of pathology is authentically known and eliminated, the state can improve. But for most of people with the acquired color-blindness, damage, as a rule, constant.
At hereditary color-blindness both eyes are involved in pathological process, this defect remains  invariable during all human life. In certain cases the acquired deficit of color sight is shown only in one eye and for a short time.