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The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Eye color is defined by the iris.
Some circle the circumference of the iris and the majority radiate toward the pupil. Blood vessels and nerves intersperse this mesh. In dark eyes, the stroma often contains pigment granules. Blue eyes and the eyes of albinos, however, lack pigment. Structure of the iris and surrounding parts showing the stroma of iris (stroma iridis).
Pupil, 7. Corneosclera with 8. Cornea, 9. Trabecular meshwork and Schlemm's canal. 10. Corneal limbus and 11. Sclera; 12. Conjunctiva, 13. Uvea with 14. Iris, 15. Ciliary body. The anterior segment or anterior cavity [1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body ...
The posterior chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm (0.94 in). An area termed the limbus connects the cornea and sclera. The iris is the pigmented circular structure concentrically surrounding the centre of the eye, the pupil, which appears to be black.
The structure of the mammalian eye owes itself completely to the task of focusing light onto the retina. This light causes chemical changes in the photosensitive cells of the retina, the products of which trigger nerve impulses which travel to the brain. [18] In the mammalian eye, light enters the pupil and is focused on the retina by the lens.
The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. [1] It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil.
The pupillary sphincter muscle and pupillary dilator muscle control the iris to adjust the size of the pupil to adjust how much light enters into the eye. The pupillary dilator muscle increases the pupillary diameter and it is arranged radially, but the pupillary sphincter muscle is responsible for the constriction of the pupil's diameter and ...
The right consensual reflex is intact. When the left eye is stimulated by light, the right pupil constricts, because the afferent limb on the left and the efferent limb on the right are both intact. The right direct reflex is intact. When light is shone into right eye, right pupil constricts.