Episcleral layer

Last updated
Episcleral layer
Details
Identifiers
Latin lamina episcleralis
TA A15.2.02.008
FMA 58362
Anatomical terminology

The episclera is the outermost layer of the sclera (the white of the eye). [1] It is composed of loose, fibrous, elastic tissue and attaches to Tenon's capsule. [1]

Sclera

The sclera, also known as the white of the eye, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some elastic fiber. In humans, the whole sclera is white, contrasting with the coloured iris, but in other mammals the visible part of the sclera matches the colour of the iris, so the white part does not normally show. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, fatty deposits on the sclera can make it appear slightly yellow. Many people with dark skin have naturally darkened sclerae, the result of melanin pigmentation.

Tenons capsule

The fascia bulbi is a thin membrane which envelops the eyeball from the optic nerve to the limbus, separating it from the orbital fat and forming a socket in which it moves.

A vascular plexus is found between the bulbar conjunctiva and the sclera consisting of two layers of vessels, the superficial episcleral vessels and the deep episcleral vessels.

Conjunctiva outer covering of sclera

The conjunctiva is a tissue that lines the inside of the eyelids and covers the sclera. It is composed of unkeratinized, stratified squamous epithelium with goblet cells, and stratified columnar epithelium. The conjunctiva is highly vascularised, with many microvessels easily accessible for imaging studies.

Clinical significance

In episcleritis, the episclera and Tenon's capsule are infiltrated with inflammatory cells. [2]

Episcleritis

Episcleritis is a benign, self-limiting inflammatory disease affecting part of the eye called the episclera. The episclera is a thin layer of tissue that lies between the conjunctiva and the connective tissue layer that forms the white of the eye (sclera). Episcleritis is a common condition, and is characterized by the abrupt onset of painless eye redness.

Related Research Articles

Pterygium (conjunctiva) A pinkish, triangular tissue growth on the cornea of the eye

A pterygium is a pinkish, triangular tissue growth on the cornea of the eye. It typically starts on the cornea near the nose. It may slowly grow but rarely grows so large that the pupil is covered. Often both eyes are involved.

Uvea pigmented middle of the three concentric layers that make up an eye

The uvea (/ˈjuːvɪə/), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye. Its use as a technical term in anatomy and ophthalmology is relatively modern.

Subconjunctival bleeding bleeding underneath the conjunctiva

Subconjunctival bleeding, also known as subconjunctival hemorrhage, is bleeding underneath the conjunctiva. The conjunctiva contains many small, fragile blood vessels that are easily ruptured or broken. When this happens, blood leaks into the space between the conjunctiva and sclera.

Red eye (medicine) type of eye disease

A red eye is an eye that appears red due to illness or injury. It is usually injection and prominence of the superficial blood vessels of the conjunctiva, which may be caused by disorders of these or adjacent structures. Conjunctivitis and subconjunctival hemorrhage are two of the less serious but more common causes.

Enucleation is the removal of the eye that leaves the eye muscles and remaining orbital contents intact. This type of ocular surgery is indicated for a number of ocular tumors, in eyes that have suffered severe trauma, and in eyes that are otherwise blind and painful.

Scleritis Human disease

Scleritis is a serious inflammatory disease that affects the white outer coating of the eye, known as the sclera. The disease is often contracted through association with other diseases of the body, such as granulomatosis with polyangiitis or rheumatoid arthritis. There are three types of scleritis: diffuse scleritis, nodular scleritis, and necrotizing scleritis. Scleritis may be the first symptom of onset of connective tissue disease.

Anterior ciliary arteries

The anterior ciliary arteries are seven small arteries in each eye-socket that supply the conjunctiva, sclera and the rectus muscles. They are derived from the muscular branches of the ophthalmic artery.

Trabeculectomy is a surgical procedure used in the treatment of glaucoma to relieve intraocular pressure by removing part of the eye's trabecular meshwork and adjacent structures. It is the most common glaucoma surgery performed and allows drainage of aqueous humor from within the eye to underneath the conjunctiva where it is absorbed. This outpatient procedure was most commonly performed under monitored anesthesia care using a retrobulbar block or peribulbar block or a combination of topical and subtenon anesthesia. Due to the higher risks associated with bulbar blocks, topical analgesia with mild sedation is becoming more common. Rarely general anesthesia will be used, in patients with an inability to cooperate during surgery.

Eye neoplasm sensory system cancer located in the eye that is characterized by uncontrolled cellular proliferation in the eye

Eye neoplasms can affect all parts of the eye, and can be a benign tumor or a malignant tumor (cancer). Eye cancers can be primary or metastatic cancer. The two most common cancers that spread to the eye from another organ are breast cancer and lung cancer. Other less common sites of origin include the prostate, kidney, thyroid, skin, colon and blood or bone marrow.

Ciliary Body Melanoma is a type of cancer arising from the coloured part (uvea) of the eye.

Ocular prosthesis type of craniofacial prosthesis

An ocular prosthesis, artificial eye or glass eye is a type of craniofacial prosthesis that replaces an absent natural eye following an enucleation, evisceration, or orbital exenteration. The prosthesis fits over an orbital implant and under the eyelids. Though often referred to as a glass eye, the ocular prosthesis roughly takes the shape of a convex shell and is made of medical grade plastic acrylic. A few ocular prostheses today are made of cryolite glass. A variant of the ocular prosthesis is a very thin hard shell known as a scleral shell which can be worn over a damaged or eviscerated eye. Makers of ocular prosthetics are known as ocularists. An ocular prosthesis does not provide vision; this would be a visual prosthesis. Someone with an ocular prosthesis is totally blind on the affected side and has monocular vision.

Periscleral lymph space

The periscleral lymph space or episcleral space of the eye is the space between the outer surface of the sclera and the inner surface of the capsule of Ténon. It is continuous with the subdural and subarachnoid spaces, and is traversed by fine bands of connective tissue.

Ocular immune system

The ocular immune system protects the eye from infection and regulates healing processes following injuries. The interior of the eye lacks lymph vessels but is highly vascularized, and many immune cells reside in the uvea, including mostly macrophages, dendritic cells, and mast cells. These cells fight off intraocular infections, and intraocular inflammation can manifest as uveitis or retinitis. The cornea of the eye is immunologically a very special tissue. Its constant exposure to the exterior world means that it is vulnerable to a wide range of microorganisms while its moist mucosal surface makes the cornea particularly susceptible to attack. At the same time, its lack of vasculature and relative immune separation from the rest of the body makes immune defense difficult. Lastly, the cornea is a multifunctional tissue. It provides a large part of the eye’s refractive power, meaning it has to maintain remarkable transparency, but must also serve as a barrier to keep pathogens from reaching the rest of the eye, similar to function of the dermis and epidermis in keeping underlying tissues protected. Immune reactions within the cornea come from surrounding vascularized tissues as well as innate immune responsive cells that reside within the cornea.

Scleral reinforcement surgery

Scleral reinforcement is a surgical procedure used to reduce or stop further macular damage caused by high myopia, which can be degenerative.

Conjunctivochalasis Human disease

Conjunctivochalasis is a common eye surface condition characterized by the presence of excess folds of the conjunctiva located between the globe of the eye and the eyelid margin.

Scleral tattooing

Scleral tattooing is the practice of tattooing the sclera, or white part of the human eye. The dye is not injected into the tissue, but between two layers of the eye, where it spreads out over a large area. The process is not common. Some procedures have caused loss of vision, severe permanent pain, and loss of the eye.

References

  1. 1 2 Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainesville, Florida: Triad Publishing Company, 1990.
  2. Heath, G. "The episclera, sclera and conjunctiva: An overview of relevant ocular anatomy." Archived 2013-05-13 at the Wayback Machine .OT. February 10, 2006.