On July 12th, National Different Colored Eyes Day recognizes those who have two different colored eyes. Many people captivate us with their eye color; others do so because they have two different colored eyes. This day celebrates them in all their uniqueness!
Having two different colored eyes is a condition called heterochromia. Three types of heterochromia exist:
- Complete heterochromia – one iris is a different color from the other.
- Partial heterochromia or sectoral heterochromia – part of one iris is a different color from the rest of the iris.
- Central heterochromia – an inner ring is a different color than the rest of the iris.
The concentration and distribution of melanin determine the eye color, specifically the color of the irises. The affected eye may be hyperpigmented (hyperchromic) or hypopigmented (hypochromic). Additionally, the excess of melanin indicates hyperplasia of the iris tissues, whereas a lack of melanin indicates hypoplasia.
Most cases of heterochromia are hereditary, caused by a disease or syndrome, or due to an injury. However, just one eye may change color following certain diseases or injuries.
Two syndromes that may cause different colored eyes are mosaicism and chimerism. Mosaicism involves two or more populations of cells within a single individual. Chimaerism occurs when two or more fertilized eggs merge, producing a single individual.
Other symptoms associated with heterochromia include patches of lighter skin or deafness. Infants who develop different colored eyes after birth should be evaluated by their pediatrician to be sure no additional care is necessary. When eye color changes occur due to injury or are sudden, seek a doctor’s care. Sometimes the condition can be severe.
A few celebrities are known to have two different colored eyes include David Bowie, Christopher Walken, Dan Aykroyd, Jane Seymour, and Mila Kunis.