The color of the human eye: A review of morphologic correlates and of some conditions that affect iridial pigmentation

Don’t it make my blue eyes brown: heterochromia and other abnormalities of the iris

“…Iris stromal, ciliary body, and choroidal melanocytes are all derived from the neural crest, a transient population of cells, unique to vertebrates. 1,2 Uveal melanocytes differ from their cutaneous counterparts in one important respect: cutaneous melanocytes 'inoculate' melanosomes into the surrounding epithelial cells; by contrast, uveal melanocytes remain continent and do not release melanosomes into the surrounding tissues. The posterior pigment epithelium forms the posterior layer and is neuroectodermal in origin.…”

“…It consists of two layers of cuboidal pigment cells, which are tightly joined to each other by numerous intercellular junctions. 1,2 It is believed that there are four main factors, which determine iris colour: the pigment granules within the posterior pigment epithelium, the concentration of pigment within the iris stromal melanocytes, the nature of melanin pigment within the iris melanocytes, and the light-scattering and absorption properties of the extracellular stromal matrix. 3,4 It is generally considered that the concentration of melanosomes in the posterior pigment epithelium is relatively constant in normal individuals and as a result it has little impact differences in normal eye colour.…”

“…Light of longer wavelength readily penetrates the iris and is absorbed, whereas light with a shorter wavelength is reflected back and scattered by the stromal matrix. 2,3 The pigment content of the iris stroma and anterior border layer is responsible for determining all of the shades of iris colour from green to dark brown. Increasing pigment within the iris stroma leads to greater light absorption and the resulting darker eye colour.…”

Replicated Linkage for Eye Color on 15q Using Comparative Ratings of Sibling Pairs

“…Although the number of melanocytes does not differ between eye colors, the melanin pigment quantity, packaging and quality does vary, resulting in a range of different eye shades (Boissy, 1998;Imesch et al, 1997;Prota et al, 1998;Sturm and Frudakis, 2004). The apparently nonmendelian examples of eye color transmission from parents to offspring, combined with the quantitative nature of iris pigmentation indicate that the inheritance of eye color is influenced by several different genes (Badano and Katsanis, 2002;Sturm and Frudakis, 2004).…”

Incidence and severity of iris pigmentation on latanoprost-treated glaucoma eyes

“…Application of the prostaglandin analogue latanoprost, on the other hand, leads to an increase in iris pigmentation in some patients. 7 Latanoprost is an ester product analogue of prostaglandin F2 alpha, which effectively reduces intraocular pressure by increasing uveoscleral outflow rather than altering conventional trabeculo-canalicular aqueous outflow. The intraocular pressure lowering effect of latanoprost lasts for 20-24 h after a single dose.…”