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The ciliary body is a ring-shaped thickening of tissue inside the eye that divides the posterior chamber from the vitreous body. It contains the ciliary muscle, vessels, and fibrous connective tissue. Folds on the inner ciliary epithelium are called ciliary processes, and these secrete aqueous humor into the posterior chamber. The aqueous humor ...
The ciliary fibers have circular (Ivanoff), [12] longitudinal and radial orientations. [13] According to Hermann von Helmholtz's theory, the circular ciliary muscle fibers affect zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing. When the ciliary muscle ...
Changes in contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or farther images to come into focus on the retina; this process is known as accommodation. [1] The reflex, controlled by the parasympathetic nervous system , involves three responses: pupil constriction, lens accommodation, and convergence.
A spasm of accommodation (also known as a ciliary spasm, an accommodation, or accommodative spasm) is a condition in which the ciliary muscle of the eye remains in a constant state of contraction. Normal accommodation allows the eye to "accommodate" for near-vision. However, in a state of perpetual contraction, the ciliary muscle cannot relax ...
The lens is suspended to the ciliary body by the suspensory ligament (zonule of Zinn), made up of hundreds of fine transparent fibers which transmit muscular forces to change the shape of the lens for accommodation (focusing). The vitreous body is a clear substance composed of water and proteins, which give it a jelly-like and sticky ...
The zonule of Zinn (/ ˈ t s ɪ n /) (Zinn's membrane, ciliary zonule) (after Johann Gottfried Zinn) is a ring of fibrous strands forming a zonule (little band) that connects the ciliary body with the crystalline lens of the eye. [1] The Zonular fibers a viscoelastic cables, although their component microfibrils are stiff structures.
At short focal distance the ciliary muscle contracts, stretching the ciliary body and relieving some of the tension on the suspensory ligaments, allowing the elastic lens to become more spherical, increasing refractive power. Changing focus to an object at a greater distance requires a thinner less curved lens.
The ciliary muscle controls accommodation by altering the shape of the lens to be able to see an object from near to far. [ 2 ] 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.