The corpus ciliare is also known as the ciliary body or ray body and is located in the medial eye membrane. It serves accommodation, aqueous humor production, and lens suspension. If the suspension fibers of the lens break in an accident, the lens may slip out of the clamping of the ciliary body in a lens luxation.
What is the corpus ciliare?
The corpus ciliare, or ciliary body, is what the medical profession refers to as the ray body of the medial eye. The lens, among other things, is suspended from this section of the eye. The corpus ciliare assumes important tasks in the near and distance adaptation within the framework of the visual process. In addition to connective tissue and nerves, the ciliary body also contains muscles, vessels and glands. The muscles and glands of the corpus ciliare are also known as the ciliary muscles and ciliary glands. The choroid merges with the so-called “serrated edge” into the steel body, which curves inward toward the lens like an annular bulge. The ciliary processes at the apex of the corpus ciliare are also known as the ciliary rim and find support at the lens equator. So-called zonular fibers originate here, the entirety of which the medical profession calls zonula ciliaris. The lens is clamped into the zonula ciliaris. The total system around the ciliary body merges forward into the iris.
Anatomy and structure
The ray body of the eye is covered by the pars ciliaris retinae. This is a multilayered epithelium that is part of the retina. Inside the ciliary body is the ciliary muscle, which consists of smooth muscle and serves to restrain the lens. Via suspensory fibers, this ring-shaped muscle is connected to the ciliary gland, which produces the aqueous humor. The oculomotor nerve or third cranial nerve passes through the ciliary muscle. The corpus ray itself is composed of pigmented, loose, and collagenous connective tissue that is supplied with blood through the fenestrated steel ciliary body. The corpus ciliare receives its general sensitivity from the nervi ciliares longi et breves.
Function and Tasks
Without the ciliary body, humans would not be able to see, or rather would only be able to see in a very blurry manner. Namely, in addition to lens suspension, the corpus ciliare serves to accommodate near and distance vision and to produce aqueous humor. In terms of accommodation, the ciliary body is involved in perceptions at a distance above and below five meters. This threshold is considered the boundary between near and distance vision. During near accommodation, the ciliary muscle contracts, narrowing the inner circumference of the ray body. As a result, the ciliary fibers that attach the lens relax. The inherently elastic lens thus acquires the shape of a sphere. It thus reduces its radius of curvature and also increases its own refractive power through this transformation. During distance adaptation, the reverse process takes place. The ciliary muscle relaxes during visual perception at distances of more than five meters. As a result, the suspension fibers of the lens expand. They tighten and thus deform the lens against its inherent elasticity until it has assumed a flattened shape. In addition to these effects of lens adjustment, the unpigmented cells of the ciliary body are primarily involved in the production of aqueous humor. The ciliary gland produces two mm per minute of this clear, cell-free secretion, 99 percent of which is water. The remaining percent is composed of electrolytes, immunoglobulin G, ascorbic acid, and amino acids, lactic acids, hydrogen peroxide, and glutathione. This aqueous humor serves to nourish the lens and cornea. Apart from that, it keeps the eyeball in shape and builds up intraocular pressure. The unpigmented tissue of the corpus ciliary plays a role in aqueous humor production in that its enzymes serve to hydrate carbon dioxide to carbonic acid and vice versa.
Diseases
One of the best-known diseases potentially associated with a ciliary body defect is glaucoma. Thus, an increase in intraocular pressure significantly raises the risk of glaucoma and, in extreme cases, irreparable blindness. An increase in intraocular pressure is often caused by an overproduction of aqueous humor, which can occur in the context of diseases of the ciliary gland or disturbed outflow tracts. Cloudiness of the aqueous humor may also be a possibility. Such complaints occur especially when the ciliary body is inflamed.In the case of inflammation of the anterior eye structures, in addition to the turbidity of the aqueous humor, a painful spasm of the ciliary muscle may also occur. Often, as a result of such a disease, accommodation can no longer take place. When the eye is affected by accidents, the zonular fibers of the ciliary body system, on which the lens is suspended, may also tear. When the suspension fibers of the ciliary system are damaged, lens luxation may occur. Lens luxation occurs when the lens is displaced into the anterior chamber of the eye or the vitreous cavity. In rare cases, a malignant tumor forms in the ciliary body. Such a choroidal melanoma is incurable in the metastatic stage so far. Choroidal melanomas usually grow very slowly, so that they are often associated for a long time without symptoms or with only subtle symptoms. Genetics probably plays a decisive role in the fatal metastasis of uveal melanoma. The chances of recovery from ciliary melanoma without metastasis depend mainly on the location and size of the tumor.
