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In some people, the pupils of the eyes are like keyholes
Learn how to develop the eye and why the pupil may be "defective" 
This curious phenomenon is called coloboma of the iris, or "keyhole defect" is observed in the distortion of the iris, congenital (genotypic) or acquired. Most often it occurs in the process coloboma of the eye, but sometimes occurs after an injury or surgery postponed.
Eyeballs are beginning to emerge about the 22nd day of the fetus, and at first look like small balls on the legs. The beginnings of the future eyes appear in the forebrain and gradually "pushed" to them outside, while the ectoderm (outer layer of tissue in the embryo) thickens, and each bowl there are deepening: Imagine that you are a finger press on the ball of dough, to make him a cup - roughly the same principle developed eyes. Gradually cavity "cup" is formed from the thickening of the ectoderm the lens and the glass wall of the eye lens to merge, forming the germ of the pupil.
When the internal structure of the eye virtually formed around the developing optic cup outer shell - vascular, sclera (protein shell) and the cornea. As a result, some deviations occur improper closing of the embryonic fissure of the optic cup, and as a result there is a "keyhole". This phenomenon is observed in the middle of one of the 10 thousand newborns.
As a rule, congenital coloboma is characterized by impaired ability to regulate the amount of light entering the eye, as well as developmental disorders of the vascular system of the eye. People with coloboma suffer from slight blurred vision and can not tolerate bright light. Currently, the deviation is corrected surgically (with significant visual impairment), and in dimly expressed forms patients use mesh tinted glasses and contact lenses with a transparent center, to limit the amount of light passing through the pupil.
via factroom.ru
This curious phenomenon is called coloboma of the iris, or "keyhole defect" is observed in the distortion of the iris, congenital (genotypic) or acquired. Most often it occurs in the process coloboma of the eye, but sometimes occurs after an injury or surgery postponed.
Eyeballs are beginning to emerge about the 22nd day of the fetus, and at first look like small balls on the legs. The beginnings of the future eyes appear in the forebrain and gradually "pushed" to them outside, while the ectoderm (outer layer of tissue in the embryo) thickens, and each bowl there are deepening: Imagine that you are a finger press on the ball of dough, to make him a cup - roughly the same principle developed eyes. Gradually cavity "cup" is formed from the thickening of the ectoderm the lens and the glass wall of the eye lens to merge, forming the germ of the pupil.
When the internal structure of the eye virtually formed around the developing optic cup outer shell - vascular, sclera (protein shell) and the cornea. As a result, some deviations occur improper closing of the embryonic fissure of the optic cup, and as a result there is a "keyhole". This phenomenon is observed in the middle of one of the 10 thousand newborns.
As a rule, congenital coloboma is characterized by impaired ability to regulate the amount of light entering the eye, as well as developmental disorders of the vascular system of the eye. People with coloboma suffer from slight blurred vision and can not tolerate bright light. Currently, the deviation is corrected surgically (with significant visual impairment), and in dimly expressed forms patients use mesh tinted glasses and contact lenses with a transparent center, to limit the amount of light passing through the pupil.
via factroom.ru
