Skip to main content

Stroma of Cornea

The cornea functions to be the clear front in the surface of the eyes. This lie directly in front of both pupil and iris allowing the light to enter the eye. It is wider than the length of its height. The primary function of the cornea is it sets a clear glass for the eye in where the light enters. Other than that, the cornea also has a different function such as it provides 65 up to 75 percent of focusing power to the eye. This gives the most critical part of the eye, and once it has been damaged, it can result in some unwanted eye disorder or deficiency to the eyes such as astigmatism, farsightedness, and nearsightedness. This is the result of the symmetry of the cornea itself. The focusing power of the eye or the cornea is a crystalline-like lens that is located just directly behind the pupil of the eye.

The corneal stroma is a part of the eye which is in a dense connective tissue or a remarkable regularity. The properties of the corneal stroma are tough, unyielding, fibrous, and entirely transparent. It is placed in the center of the cornea itself. As its center, the human stroma of cornea is made up of 200 flatten lamellae or the layers of the collagen fibrils that are being overlaid to one another. The thickness of this part is about 1.5 to 2.5 μm. In the anterior lamellae, interweave is more than the posterior lamellae. Fibrils of each of the lamellae are perfectly parallel to each other. On a different angle, there are those adjacent lamellae. These lamellae are being produced by modified fibroblasts known as keratocytes or the corneal connective tissues cells. These lamellae occupy about 10% of the substantia propria on the cornea.

Aside from the cells that cover the cornea, the major non-aqueous elements that cover the stroma are the proteoglycans and collagen fibrils. Collagen fibrils are a mixture of both type 1 and type 5 collagens. These kinds of molecules are sloped in about fifteen degrees on the fibril axis. In conclusion of this, the axial periodicity of the fibrils itself is being reduced up to 65 nm or is measure in tendons with 67 nm in periodicity. In diameter, the fibrils are remarkably the same, and it differs from species to species. It creates a very decent and chronological order in its structure. In humans, the collagen fibrils create 31nm in diameter.

The proteoglycan is made of small proteins cored to one or more glycosaminoglycan or called as the GAG. These glycosaminoglycan or GAG chains are negative charges. In the cornea, you can find two varying types of proteoglycans. These are the Keratan Sulphate or KS and the Chondroitin sulphate/dermatan sulphate or the CD/CS. In the bovine cornea, the total length of both chondroitin sulphate and dermatan sulphate or the CD/DS proteoglycans is 70nm. On the other hand, the keratan sulphate or the KS length about 40 nm long. These proteoglycan protein cores are attached to the surface of the collagen fibrils with the glycosaminoglycan chains projecting in an upward motion.

The chains from the GAG can form antiparallel links with the other GAG chains from the adjacent fibrils present in the element. The positively charged ions are made through the mediation of these chains. When the adjacent collagen fibrils are formed, they create the bridge and its subjects to thermal motions in which it prevents them from presumptuous an extended conformation. As a result, the forces that the collagen fibril forms, they tend to move the adjacent fibril closer to each other. Simultaneously, the charges that are being released by the GAG chains attract the ions and other molecules such as water in a process called the Donnan Effect. This effect results in an increased water volume that occurs between the fibrils that result to create a force that pushes the fibrils apart. There is a balance that is created in between the attractive and repulsive forces of the Donnan effect, it for both outcomes to each a specific inter-fibrillar distances. This will depend on the present type of proteoglycans. As an outcome of the separation that happens between the adjacent and collagen fibrils tend to be identical.

The stromal transparency of the corneal stroma is only a product of consequence of a remarkable degree of the order in the organization if the collagen fibrils present in the lamellae and of the fibril diameter consistency. When the light enters the cornea, the light is being scattered in every fibril. The organization and the diameter of each fibril are that when the scattered light interferes productively in an upward direction. This process allows the light that passes through the cornea up to the retina.

The lamellae that create the fibrils are continuously direct to the sclera or also known as the white of the eye. This is the outer protective layer of the eye. The sclera is grouped in bundles of fiber. Most of the collagen fibers go to a temporal-nasal direction than it to go in the superior to inferior direction.

Throughout the development of the embryo, the stroma of the cornea is being derived from the neural crest, and this is the source of the mesenchyme in the neck and head of the baby. This can contain mesenchymal cells in the stem.

Disorders of the Stroma of Cornea

1. Keratoconus is a disorder in the eye in which it results in more progressive thinning of the cornea. It is caused by some unsystematic lamellae that leads to the thinning and a conical shape of the cornea.

2. Macular corneal dystrophy, this is a rare condition that affects the stroma of the cornea. This is associated with the loss of keratin sulfate or KS.

There are some things you need to follow in taking care of your eyes. There are some small things you can do. If you experienced some of the unwanted things in your eyes, you could consult your optical doctor for further info.