What makes up the ciliary body

This is known as the intraocular pressure IOP. Ocular hypertension is the term used to describe higher-than-normal IOP.

This elevated pressure can in turn lead to glaucoma — the term used to describe a group of related eye conditions that cause damage to the optic nerve and can lead to blindness if left untreated. Carbonic anhydrase inhibitors such as Azopt brinzolamide and Trusopt dorzolamide. Alpha-adrenergic agonists such as Alphagan P brimonidine and Iopidine apraclonidine. Presbyopia is the normal, age-related loss of ability of the eyes to focus on near objects.

It usually occurs sometime after age Presbyopia occurs because the lens of the eye thickens over time and loses its natural flexibility. The ciliary body retains its ability to function, but the lens fails to change shape to enable near objects to come into focus. Fortunately, presbyopia is treatable with eyeglasses , contact lenses or vision surgery.

For some, over-the-counter reading glasses are a simple solution for presbyopia. Problems related to the ciliary body can be associated with serious eye conditions such as glaucoma. The oblique fibers radial or intermediate connect the longitudinal and circular fibers. The contraction of these fibers may widen the uveal trabecular spaces. Traditional views hold that the vasculature of the ciliary body is supplied by the anterior ciliary arteries and the long posterior ciliary arteries, forming the major arterial circle near the root of the iris, wherefrom branches supply the iris, ciliary body and the anterior choroid.

Recent studies in primates have shown a complex vascular arrangement with collateral circulation on at least three levels [ 7 , 8 ]: an episcleral circle formed by anterior ciliary branches; an intramuscular circle formed through the anastomosis between anterior ciliary arteries and long posterior ciliary artery branches; and the major arterial circle formed primarily, if not exclusively, by paralimbal branches of the long posterior ciliary arteries.

The major arterial circle is the immediate vascular supply of the iris and ciliary processes [ 8 , 9 ]. The inner surfaces of the ciliary processes and the pars plana are lined by two layers of epithelium.

The outer layer is the pigmented epithelium, which is composed of low cuboidal cells and is adjacent to the stroma and continuous with the retinal pigmented epithelium. The inner layer is formed by the nonpigmented epithelium, a columnar epithelium, adjacent to the aqueous humor in the posterior chamber and continuous with the retina. The major innervation is provided by ciliary nerve branches third cranial nerve-oculomotor , forming a rich parasympathetic plexus.

There are also sympathetic fibers originating from the superior cervical ganglion which keep pace with arteries and their branches. Histology of human ciliary epithelia. Each ciliary process is composed of a central stroma and capillaries, covered by a double layer of epithelium. The ciliary process capillaries occupy the center of each process [ 10 ]. The capillary endothelium is thin and fenestrated, representing areas with fused plasma membranes and no cytoplasm, which may have an increased permeability.

A basement membrane surrounds the endothelium and contains mural cells or pericytes. The stroma is very thin and surrounds the vascular tissues, separating them from the epithelial layers. The stroma is composed of ground substance mucopolysaccharides, proteins and plasma of low molecular size , collagen connective tissue especially collagen type III and cells of connective tissue and the blood [ 11 ].

Ciliary process epithelia consist of two layers, with the apical surfaces in apposition to each other. The pigmented epithelium is the outer layer, and the cuboidal cells contain numerous melanin granules in their cytoplasm.

The nonpigmented epithelium is composed of columnar cells with numerous mitochondria, well-developed endoplasmic reticulum seen in the cytoplasm, extensive infoldings of the membranes and tight junctions between the apical cell membranes.

The basement membrane faces the aqueous humor, is composed of fibrils in a glycoprotein with laminin and collagens I, III and IV [ 16 ]. The apical cells of this membrane are connected by tight junctions zonulae occludentae , creating a permeability barrier, which is an important component of the blood-aqueous barrier called the internal limiting membrane. Adjacent cells within each epithelial layer and between the apical cells of the two layers are connected by gap junctions, tight junctions and desmosomes.

The apical membranes of the nonpigmented epithelium are also joined by tight junctions [ 12 , 13 , 14 ]. The anterior portion of the nonpigmented ciliary epithelium has the morphologic features of a tissue involved in active fluid transport, i.

There are many indications that the aqueous humor is produced in the anterior portion of the nonpigmented epithelia of ciliary processes [ 17 , 18 , 19 ]. There is a potential space between the two epithelial layers, called "ciliary channels". The aqueous humor may be secreted into this space after beta-adrenergic agonist stimulation, but this notion requires additional studies [ 20 ]. The iris inserts into the anterior side of the ciliary body and separates the aqueous compartment into a posterior and anterior chamber.

The angle formed by the iris and the cornea is the anterior chamber angle 6. The aqueous humor is formed by the ciliary process, passes from posterior chamber to the anterior chamber through the pupil, and leaves the eye at the anterior chamber angle. The posterior wall of the scleral sulcus is formed by a group of fibers, parallel to the limbus that project inward like a fibrous ring, called the scleral spur.

The spur is attached anteriorly to the trabecular meshwork and posteriorly to the sclera and the longitudinal portion of the ciliary muscle [ 26 ]. When the iris inserts into the anterior side of the ciliary body, it leaves a variable width of the latter structure visible between the iris and scleral spur, corresponding to the ciliary body band.

Gonioscopically, it appears as a brownish band. The trabecular meshwork consists of connective tissue surrounded by endothelium. This tissue may be divided into three portions: a uveal meshwork, b corneoscleral meshwork and c juxtacanalicular tissue 6.

By gonioscopy, the trabecular meshwork can be separated into two portions: an anterior named non-pigmented and a posterior pigmented. The inner layers of the trabecular meshwork can be observed in the anterior chamber angle and are referred to as the uveal meshwork. Types of Cancer Treatment. Side Effects of Cancer Treatment. Clinical Trials Information. A to Z List of Cancer Drugs. Questions to Ask about Your Treatment. Feelings and Cancer. Adjusting to Cancer. Day-to-Day Life. Support for Caregivers.

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