Microphthalmia (Greek: μικρός, mikros, small, ὀφθαλμός, ophthalmos, eye, also referred as microphthalmos, is a developmental disorder of the eye in which one (unilateral microphthalmia) or both (bilateral microphthalmia) eyes are abnormally small and have anatomic malformations. Microphthalmia is a distinct condition from anophthalmia and nanophthalmia. Although sometimes referred to as simple microphthalmia, nanophthalmia is a condition in which the size of the eye is small but no anatomical alterations are present. Presentation
Microphthalmia is a congenital disorder in which the globe of the eye is as unusually small and structurally disorganized. While the axis of an adult human eye has an average length of about 23.8 mm (0.94 in), a diagnosis of microphthalmia generally corresponds to an axial length below 21 mm (0.83 in) in adults. Additionally, the diameter of the cornea is about 9–10.5 mm (0.35–0.41 in) in affected newborns and 10.5–12 mm (0.41–0.47 in) in adults with the condition. The presence of a small eye within the orbit can be a normal incidental finding but in many cases it is atypical and results in visual impairment. The prevalence of this condition is around 1 in 10,000 births, and it affects roughly 3–11% of blind children. Causes
It has been postulated that microphthalmia arises as a result of interference with postnatal eye growth, in contrast to anophthalmia which originates much earlier during fetal development. Genetic causes of microphthalmia include chromosomal abnormalities (e.g. Patau syndrome, mosaic trisomy 9, 13q deletion syndrome, Wolf–Hirschhorn syndrome) or monogenetic Mendelian disorders (e.g. CHARGE syndrome, Fraser syndrome, oculofaciocardiodental syndrome, Lenz microphthalmia syndrome).
This has ranged from display of unclothed African piebalds in "freak" shows and postcards of the early 20th century to the forcing of piebalds (as in the case of albinos) to work long hours exposed to the sun (producing high rates of lethal skin cancers), to the use of piebald humans, including children, in risky medical experiments. The National Organization of Albinism and Hypopigmentation, as well as organizations such as Under the Same Sun, work to promote awareness of all forms of cutaneous variation and their medical implications, and to highlight human rights issues, especially the plight of albinos subject to extreme persecution in parts of Africa. Etymology
The word "piebald" originates from a combination of "pie," from "magpie", and "bald", meaning "white patch" or spot. The reference is to the distinctive black-and-white plumage of the magpie. See also
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