If you are concerned about abnormal coloration of any part of the eye, I recommend that you see an optometrist
or healthcare professional for formal evaluation. Eye color can have multiple normal variations based on genetics. Eye color is a pleiotropic trait, meaning multiple genes effect the phenotype, or physical appearance of the eye color. Blue is a more recessive trait, while brown is dominant. There can be variations between, depending on genetics, to produce appearances such as hazel colored eyes. For many individuals, on close examination, they will have what appears to be a mix of colors, including browns, green, gray and blue. Most benign coloring is distrubuted evenly throughout the iris, e.g. brown mixed with green throughout the entire circumference of the eye. Asymmetric brown coloration, such as a singular brown cluster that is visible can be more concerning for abnormal melanocyte growth. Ocular melanosis is a condition that effects one in several thousand people and is associated with increased melanocyte growth and deposition of melanin, a brown pigment, in the eye. This may lead to the appearance of dark spots on the sclera (the white part of the eye) or on the iris, e.g. half the iris being brown. These spots need to be followed more closely in order to monitor for the development of malignant growth over time.