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

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      Iris color can be affected by a variety of ocular disorders. It is suspected that iris color may not remain constant throughout life. These observations have drawn attention to the morphologic correlates of iris color and its regulation. Differences in the iris color of normal eyes are the result of variable amounts of melanin pigment granules within a constant number of melanocytes in the superficial stroma of the iris. These melanocytes seem to reach their genetically determined amount of melanin in early childhood, and their melanin content usually remains constant in adulthood. Diseases such as Horner's syndrome and Fuchs' heterochromic iridocyclitis affect iris color, resulting in a decrease of iris pigmentation. Evidence suggests that melanin content of some melanocytes is subject to adrenergic regulation even past childhood. Application of the prostaglandin analogue latanoprost, on the other hand, leads to an increase in iris pigmentation in some patients. Studies with cultured dermal and uveal melanocytes, as well as with uveal melanoma cells, however, show no increase in cell proliferation when treated with latanoprost in vitro. The mechanisms by which latanoprost affects regulation of iris pigmentation requires further investigation.

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        • Albert DM
        • Ruzzo MA
        • McLaughlin MA
        • et al.
        Establishment of cell lines ofuveal melanoma, Methodology and characteristics.
        Invest Ophthalmol Vis Sci. 1984; 25: 1284-1299
        • Aim A
        • Camras CB
        • Watson PG
        Phase III latanoprost studies in Scandinavia, the United Kingdom and the United States.
        Surv Ophthalmol. 1997; 41: S105-S110
        • Calhoun FP
        Causes ofheterochromiawith special reference to paralysis of the cervical sympathetic.
        Am J Ophthalmol. 1919; 2: 255-269
        • Camras C
        • et al.
        Comparison of latanoprost and timolol in patients with ocular hypertension and glaucoma — Preliminary results of the USA multicenter trial.
        in: Kriegelstein G Glaucoma Update. Kaden Verlag, Heidelberg1995
        • Camras C
        • et al.
        Comparison of latanaprost and timolol in patients with ocular hypertension and glaucoma — A six month, masked USA multicenter trial.
        Ophthalmology. 1996; 103: 138-147
        • Carino OB
        • Matheny AP
        • DeRousseau CJ
        • Bito LZ
        Changes in iridial pigmentation past childhood through adolescence (abstract).
        Invest Ophthalmol Vis Sci. 1994; 35: 1530
        • Davenport GC
        • Davenport CB
        Heredity of eye-color in man.
        Science. 1907; 26: 589-592
        • Dietrich CE
        Zur Feinstruktur der Melanocyten in dermenschlichen Iris.
        Albert v Graefes Arch Klin Exp Ophthalmol. 1972; 183: 317-333
        • Dryja TP
        • Albert DM
        Lack of adrenergic influence on the pigmentation of iris nevus cells.
        Arch Ophthalmol. 1980; 98: 1996
        • Duke-Elder S
        • Wybar KC
        The iris.
        in: Duke-Elder S Anatomy of the Visual System. Vol 2. CV Mosby, St Louis1961: 167-185
        • Eagle R
        Iris pigmentation and pigmented lesions, An ultrastructural study.
        Trans Am Ophthalmol Soc. 1988; 88: 581-687
        • Feeney L
        • Grieshaber JA
        • Hogan MJ
        Studies on human ocular pigment.
        in: Rohen JW The Structure of the Eye. II. Symposium. Schattauer Verlag, Stuttgardt1965: 535-548
        • Fine BS
        • Yanoff M
        Ocular Histology, A Text and Atlas. Harper & Row, Hagerstown1979: 197-214
        • Fuchs E
        Normal pigmentierte und albinotische Iris.
        Albrecht von Graefes Arch Klin Exp Ophthalmol. 1913; 84: 521
        • Fuchs E
        Über Kompliklationen der Heterochromie.
        Z Augenheilkd. 1906; 15: 191-212
        • Ghadially F
        in: Ghadially F ed 3. Ultrastructural pathology of the cell and matrix. Vol. 2. Butterworth, London1988: 787-820
        • Hiller R
        • Sperduto RD
        • Kreuger DE
        Race, iris pigmentation, and intraocular pressure.
        Am J Epidemiol. 1982; 115: 674-683
        • Hogan M
        • Alvarado J
        • Weddel J
        Iris and anterior chamber, Histology of the human eye. WB Saunders Co, Philadelphia1971: 202-259
        • Holz FG
        • Piguet B
        • Minassian DC
        • et al.
        Decreasing stromal iris pigmentation as a risk factor for age-related macular degeneration.
        Am J Ophthalmol. 1994; 117: 19-24
        • Hu DM
        • McCormick SA
        • Ritch R
        Studies of human uveal melanocytes in vitro, Growth regulation of cultured human uveal melanocytes.
        Invest Ophthalmol Vis Sci. 1993; 34: 2220-2227
        • Imesch PD
        • Bindley CD
        • Khademian Z
        • et al.
        Melanocytes and iris color, Electron microscopic findings.
        Arch Ophthalmol. 1996; 114: 443-447
        • Jimbow K
        Formation, chemical compositions and functions of melanin pigments in mammals.
        in: Matoltsy AG Biology of the Integument. Springer Verlag, New York1986: 278
        • Jimbow K
        • Quevedo W
        • Fitzpatrick T
        • Szabo G
        Biology of melanocytes.
        in: Fitzpatrick T Dermatology in General Medicine. Vol. 1. McGraw-Hill, New York1993: 261-289
        • Kan-Mitchel J
        • Rao N
        • Albert D
        • et al.
        S100 immunophenotype of uveal melanomas.
        Invest Ophthalmol Vis Sci. 1990; 31: 1492-1496
        • Kliman GH
        • Augsberger JJ
        • Shields JA
        Association between iris color and iris melanocytic lesions.
        Am J Ophthalmol. 1985; 100: 547-548
        • Laties AM
        Ocular melanin and the adrenergic innervation to the eye.
        Trans Am Ophthalmol Soc. 1974; 72: 560-605
        • Makley M
        • Abbott K
        Heterochromia in adults, Areport of an interesting case.
        Am J Ophthalmol. 1965; 59: 927
        • McCartney ACE
        Embryological development of the eye.
        in: Garner A Klintworth GK Pathobiology of Ocular Disease, A Dynamic Approach. ed 2. Marcel Dekker, New York1994: 1255-1284
        • McCartney ACE
        • Bull TB
        • Spahon DJ
        Fuchs' heterochronfic cyclitis, an electron microscopy study.
        Trans Ophthalmol Soc UK. 1986; 105: 324-329
        • McCartney ACE
        • Riordan-Eva P
        • Howes RC
        • Spahon DJ
        Horner's syndrome, an electron microscopic study of a human iris.
        BrJ Ophthalmol. 1992; 76: 746-749
        • McKay B
        • Burke J
        Separation ofphenotypically distinct sub-populations of cultured human retinal pigment epithelial cells.
        Exp Cell Res. 1992; 213: 85-92
        • Menon IA
        • Basu PK
        • Persad S
        • et al.
        Is there any difference in the photobiological properties of melanins isolated from human blue and brown eyes?.
        BrJ Ophthalmol. 1987; 71: 549-552
        • Menon IA
        • Wakeham DC
        • Persad SD
        • et al.
        Quantitative determination of the melanin contents in ocular tissues from uman blue and brown eyes.
        J Ocular Pharmacol. 1992; 8: 35-42
        • Moses RA
        The iris and the pupil.
        in: Moses RA Adler's Physiology of the Eye. CV Mosby, St Louis1970: 372-404
        • Moss SE
        • Klein R
        • Meuer MB
        • Klein BE
        The association of iris color with eye disease in diabetes.
        Ophthalmology. 1987; 94: 1226-1231
        • Mukano K
        • Witmer R
        lnnervation ofmelanocytes in human iris.
        An electron microscopic study. Graefes Arch Clin Exp Ophthalmol. 1977; 203: 1-8
        • Nodel D
        Periocular mesenchyme, Neural crest and mesodermal interactions.
        in: Jakobiec F Ocular Anatomy, Embryology and Teratology. Harper & Row, Philadelphia1982: 97-119
        • Ringvold A
        Electron microscopic study of the iris stroma in monkey and rabbit with particular reference to intercellular contacts and sympathetic innervation of anterior layer cells.
        Exp Eye Res. 1975; 20: 349-365
        • Rootman J
        • Gallagher RP
        Color as a risk factor for iris melanoma.
        Am J Ophthalmol. 1984; 98: 558-561
        • Sandberg MA
        • Gaudio AR
        • Miller S
        • Weiner A
        Iris pigmentation and extent of disease in patients with neovascular age related macular degeneration.
        Invest Ophthalmol Vis Sci. 1994; 35: 2734-2740
        • Taylor AI
        Eye colour in the Tristan da Cunha population.
        Human Biology. 1967; 39: 316-318
        • Wilkerson CR
        • Syed NS
        • Fisher MR
        • et al.
        Melanocytes and iris color, Light microscopic findings.
        Arch Ophthalmol. 1996; 114: 437-442
        • Wistrand P
        • Stjernschantz J
        • Ohisson K
        The incidence and time-course of latanoprost-induced iridial pigmentation, as a function of eye color.
        Surv Ophthalmol. 1997; 41: S129-S138
        • Wobman P
        • Fine B
        The clump cells of Koganei.
        Am J Ophthalmol. 1972; 73: 90
        • Wolfrum P
        Über den Bau der Irisvorderfläche des menschliche Auges mit vergleichend anatomischen Bemerkungen.
        Albrecht von Graefes Arch Klin Exp Ophthalmol. 1922; 183: 317-333
        • Zinn K
        • Mockel-Pohl S
        • Villanueva V
        • Furman M
        The fine structure of the iris melanosome in man.
        Am J Ophthalmol. 1973; 76: 721-729