People with blue or grey eyes are at greater risk of vitiligo and melanoma, researchers have found. The relationship between eye colour and susceptibility to certain diseases is not clear, however.
"In the literature, we can find attempts to determine what diseases threaten us in the future, depending on eye colour. However, there are many discrepancies and the data are not very precise. Eye colour will not protect us from disease. Best we can speak of is a lower risk" - told PAP Deputy Director of the University Centre for Ophthalmology and Oncology in Katowice, Prof. Ewa Mrukwa-Kominek.
She reminded that eye colour was one of the elements of human adaptation to environmental conditions developed in the evolution process. In regions of the globe with high insolation people have dark irises, and bright irises dominate where there is little sun.
It was found that people with bright eyes, who moved from Europe to South America, more often suffered from skin cancer. In turn, people with dark irises living in Scandinavia exhibited increased incidence of tuberculosis, infections, immune disorders, and were more prone to depression.
The researchers have also found that people with brown eyes are at less risk of developing melanoma, which is the most dangerous skin cancer, very quickly spreading to other organs. In turn, people with blue eyes are more often diagnosed with vitiligo, dependent on degradation of pigmented cells.
"However, example from the literature shows that these data are not precise. In the study group of 3,000 people with vitiligo, as many as 43 percent had brown irises and only 27 percent blue irises" - said Prof. Mrukwa-Kominek.
"Researchers gather evidence that most skin diseases are genetic. They managed to identify 13 genes, the presence of which increases the risk of vitiligo. In the course of these studies, it was found that most of these people had blue and gray irises. In these people, melanoma was also found to be occurring more frequently. These dependencies are thus very complex" - she added.
People around us have eyes in different colours, from the darkest shades of brown to the brightest blue. "There was a need to standardize the classification system, leading to the development of gradual system, based on the predominant iris colour - brown, light brown, green, grey and blue, and the content of brown or yellow pigment" - explained ophthalmologist.
There are three primary colours: brown, yellow and grey, and their proportions determine the eye colour. For example, light-brown eyes have a lot of yellow and a bit of brown pigment, blue eyes have little yellow and a little brown pigment, green are blue eyes with more yellow pigment. Grey eyes are grey because they have little yellow and do not have any brown pigment. In the case of brown eyes, brown pigment is dominant.
It is believed that the brown colour of the eyes is the most common, found in 90 percent of the world\'s population. Green is in second place - 7 percent, followed by grey - 2 percent, and blue is the rarest - 1 percent.
Another study, however, indicates that about 8 percent of the world\'s population have blue eyes. The authors emphasize that blue eyes are relatively common throughout Europe and in areas inhabited by people of European origin, such as Canada, United States, Australia and several South American countries: Argentina, Uruguay, and Brazil. In other parts of the world they are rare.
Eye color depends on the amount of pigment - melanin. If is found is the smallest amount in people with bright eyes: blue, light green, grey. Most of these people have also fair complexion and blond hair. The more melanin the darker the shade of eyes, hair and skin.
"You should watching your eyes, and pay special attention to various blemishes and spots. Healthy iris has is a uniform colour and a dark ring on the border of the sclera. If you notice any worrying changes, you should immediately consult an ophthalmologist" - emphasised Prof. Mrukwa-Kominek.
PAP - Science and Scholarship in Poland, Anna Gumułka
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