Eye heterochromia is associated with a violation of the synthesis of pigment - melanin. People with this pathology have a different color of the iris. The hormone melanotropin, which is formed in the pituitary gland, enters the circulatory system and cerebrospinal fluid, spread throughout the body, while regulating the biosynthesis of melanin in the body. After that, the hormone molecule is destroyed by peptide-hydrolase cells. Therefore, in violation of the biosynthesis of melanotropin and melanin, iris heterochromia develops. It should be said that the concentration of melanin determines the color of the eyes. The color of the iris is closely related to pigmentation of the skin and hair. There are two main types of iris - light (most often gray-blue with various shades) and brown (dark and light brown). It was established that absolutely the same irises of the same person in nature do not exist (meaning the localization and concentration of the pigment).
Eye heterochromia can also occur as a result of depigmentation. Most experts are inclined to the version that true depigmentation is formed due to dystrophic processes in the iris of the eye. An important factor in the development of eye heterochromia is heredity. In this case, one eye will be the paternal color, and the second - the mother.
Do not forget that eye heterochromia develops as a result of a wide variety of diseases (iritis, glaucoma, choroiditis, siderosis, hemorrhages, etc.). At first glance, in this case, the difference in the color of the iris is considered one of the most striking symptoms. However, with a more detailed study, the underlying disease is established.
Eye heterochromia is divided into three types: secretory, full, central. A characteristic feature of secretory heterochromia is that two colors are present in one iris. With complete heterochromia, the eyes of a person are of different colors. With central heterochromia, the iris has more than two colors. Incidentally, one color is dominant, forming a ring around the pupil.
As a result of ophthalmological studies, it was noted that in people with a diagnosis of eye heterochromia, cataracts and cyclites are more often recorded. Heterochromia is equally often observed both in light-eyed blondes and in dark-eyed brunettes. Some authors argue that this pathology is still more common in blue-eyed patients. In some cases, heterochromia in people is noted from early childhood, in others - patients ascertain this fact only in adulthood. Heterochromia is often recorded in patients aged 20 to 45 years.
Heterochromia with neurogenic etiology in all cases is accompanied by normal function of the bright eye, without any kind of deposits on the surface of the cornea, opacities of the vitreous body and lens. Microscopic examination reveals a decrease in the concentration of stromal pigment compared to the other eye. In this case, the pigmentation of the iris is uniform in all its parts. This type of heterochromia is characterized by the presence of paresis of the sympathetic nerve on the side where the bleached iris is located. The development of neurogenic heterochromia is associated with increased irritability of the cervical sympathetic ganglion. Thus, this nerve affects the development of the iris and its pigment. These changes indicate serious dysfunction in the apparatus of the nervous and vascular systems. A disease such as albinism develops with a violation of the formation of retinal and mesodermal pigment. Eye heterochromia is limited to one mesodermal pigment of the iris. Another difference between albinism and heterochromia is that it does not give complications and is a family, hereditary anomaly of pigment biosynthesis in the body.