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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.
Ciliary muscle contraction initiates a pressure gradient between the vitreous and aqueous compartments that support the anterior lens shape. It is in this lens shape that the mechanically reproducible state of a steep radius of curvature in the center of the lens with slight flattening of the peripheral anterior lens, i.e. the shape, in cross ...
The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscle [3] [4] in the eye's middle layer, the uvea (vascular layer). It controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humor into Schlemm's canal .
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 ...
Constriction of the pupil occurs when the circular muscle, controlled by the parasympathetic nervous system (PSNS), contracts, and also to an extent when the radial muscle relaxes. A human adult exhibiting voluntary control over his iris muscles, where he can cause his pupil to dilate and constrict on command
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 ...
When ciliary muscles contract, the zonular tension will reduce allowing lens to assume more spherical shape. This shape change increases the focusing power of the eye allowing closer objects to come into focus. The process of changing the lens's focusing power to see closer objects more clearly is known as accommodation.
The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction. [2] The ciliary muscle, pupillary sphincter muscle and pupillary dilator muscle sometimes are called intrinsic ocular muscles [3] or intraocular muscles. [4]