"However, acid burns, even severe ones, seldom result in loss of the eye. Alkali burns, on the other hand, such as those resulting from exposure to ammonium hydroxide or ammonium chloride or other chemicals with a pH above 11.5, will cause cellular tissue in the sclera to saponify and should be considered medical emergencies requiring immediate treatment. Yellowing of the sclera is a visual symptom of jaundice. In very rare but severe cases of kidney failure and liver failure, the sclera may turn black. Sclera The sclera, also known as the white of the eye, is the opaque, fibrous, protective,"
"pass. The thickness of the sclera varies from 1mm at the posterior pole to 0.3 mm just behind the rectus muscle insertions. The sclera's blood vessels are mainly on the surface. Along with the vessels of the conjunctiva (which is a thin layer covering the sclera), those in the episclera render the inflamed eye bright red. In many vertebrates, the sclera is reinforced with plates of cartilage or bone, together forming a circular structure called the sclerotic ring. In primitive fish, this ring consists of four plates, but the number is lower in many living ray-finned fishes, and much higher"
"the sclera can make it appear slightly yellow. Many people with dark skin have naturally darkened sclerae, the result of melanin pigmentation. The human eye is relatively rare for having an iris that is small enough for its position to be plainly visible against the sclera. This makes it easier for one individual to infer where another individual is looking, and the cooperative eye hypothesis suggests this has evolved as a method of nonverbal communication. The sclera forms the posterior five-sixths of the connective tissue coat of the globe. It is continuous with the dura mater and the cornea, and"
"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. There are two types of episcleritis, nodular and simple. Nodular episcleritis lesions have raised surface. Simple episcleritis lesions are flat. There are two subtypes. In diffuse simple episcleritis, inflammation is generalized. In sectoral simple episcleritis, the inflammation is restricted to one region."
"surface. The interlensar sclera is not deeper than the lenses. This type of eye is called abatochroal. A second type of eye, called schizochroal, is unique to the Phacopina suborder, and has up to several hundreds of relatively large lenses (0.05-0.5 mm), that do not touch either, but the corneal membrane extends into the sclera outside the lens, and the sclera is deeper than the lens. The most usual type of trilobite eye, called holochroal, has usually thousands of small hexagonal lenses without an interlensar sclera, and a common cornea. Many later Eodiscina however, lost their visual organs altogether, and"
"eye, which becomes brown and then black within a few hours, upon which dust settles and the surface becomes wrinkled. Tache noir de la sclerotique Tache noire de la sclerotique (French for ""Black spot of the sclera"") is one of the ocular signs of death in which a reddish-brown discoloration is transversely arranged across the sclera. It occurs when the eyes are not completely closed so that the sclera is exposed to air. If the eyelids are open for a few hours after death, a film of cell debris and mucus forms two yellow triangles on the sclera, each at"
"μm) in thickness near its center. The posterior chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm. The cornea and sclera are connected by an area termed the limbus. The iris is the pigmented circular structure concentrically surrounding the center of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles. Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus"
"Conjunctiva The conjunctiva lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, and also stratified columnar epithelium. The conjunctiva is highly vascularised, with many microvessels easily accessible for imaging studies. The conjunctiva is typically divided into three parts: Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulation of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and"
"is the bulge of weak sclera lined by ciliary body, which occurs about 2–3 mm away from the limbus. Its common causes are thinning of sclera following perforating injury, scleritis & absolute glaucoma. it is part of anterior staphyloma On the equator of the eye (region circumferencing the largest diameter orthogonal to the visual axis). Its causes are scleritis & degeneration of sclera in pathological myopia. It occurs more commonly in the regions of sclera which are perforated by vortex veins. In the posterior segment of the eye, typically diagnosed at the region of the optic nerve or macula, deforming"
"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. In late 2007, Body Modification Ezine wrote an article describing the first three scleral tattoo procedures performed on sighted eyes. The artist known as Luna Cobra (Howard ""Howie"" Rollins) experimented on three volunteers; Shannon Larratt, Joshua Matthew Rahn and"
"decades of life. Scleritis 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 (the most common), nodular scleritis, and necrotizing scleritis (the most severe). Scleritis may be the first symptom of onset of connective tissue disease. Episcleritis is inflammation of the episclera, a less serious condition that seldom develops into scleritis. Symptoms of scleritis include: The pain of episcleritis is less"
"other vertebrates. The outer layer of the eye consists of the transparent cornea at the front, and two layers of sclera — a tough white collagen fibre layer which surrounds the rest of the eye and supports and protects the eye as a whole. The eye is divided internally by the lens into two main segments: the anterior segment and the posterior segment. The anterior chamber is filled with a watery fluid called the aqueous humour, and the posterior chamber contains the vitreous humour, a clear jelly-like substance. The lens is a transparent convex or 'lens' shaped body with a"
"Tache noir de la sclerotique Tache noire de la sclerotique (French for ""Black spot of the sclera"") is one of the ocular signs of death in which a reddish-brown discoloration is transversely arranged across the sclera. It occurs when the eyes are not completely closed so that the sclera is exposed to air. If the eyelids are open for a few hours after death, a film of cell debris and mucus forms two yellow triangles on the sclera, each at side of the iris, with base towards the margin of cornea and apex towards medial or lateral canthus of the"
"maintains the shape of the globe, offering resistance to internal and external forces, and provides an attachment for the extraocular muscle insertions. The sclera is perforated by many nerves and vessels passing through the posterior scleral foramen, the hole that is formed by the optic nerve. At the optic disc the outer two-thirds of the sclera continues with the dura mater (outer coat of the brain) via the dural sheath of the optic nerve. The inner third joins with some choroidal tissue to form a plate (lamina cribrosa) across the optic nerve with perforations through which the optic fibers (fasciculi)"
"the sclera, a thick, hard membrane which protects the inner parts of the nerves from injury. The chorioid, a thin and soft structure filled with veins and arteries, follows next and provides nourishment to the overall structure. Finally, the retina transmits nutrients to the lenses themselves. Hunayn then presents the system responsible for protecting the eye. From the outermost level, these are the conjunctiva, cornea, and uvea. While both the conjuctiva and cornea provide protection with minimizing hindrance to the lenses, the uvea has an extra function of concentrating the pneuma exiting out of the eye to prevent it from"
"Sanpaku According to Chinese medical face reading, when the white part of the eye, known as the sclera, is visible beneath the iris, it represents physical imbalance in the body and is claimed to be present in alcoholics, drug addicts and people who over-consume sugar or grain. Conversely, when the upper sclera is visible it is said to be an indication of mental imbalance in people such as psychotics, murderers, and anyone rageful. It was held that stress and fatigue may also be a cause. In either condition, it is believed that these people attract accidents and violence. In August"
"area is typical for corneal rather than scleral tissue. Sclerocornea may be concurrent with cornea plana. Sclerocornea Sclerocornea is a congenital anomaly of the eye in which the cornea blends with sclera, having no clear-cut boundary. The extent of the resulting opacity varies from peripheral to total (""sclerocornea totalis""). The severe form is thought to be inherited in an autosomal recessive manner, but there may be another, milder form that is expressed in a dominant fashion. In some cases the patients also have abnormalities beyond the eye (systemic), such as limb deformities and craniofacial and genitourinary defects. According to one"
"as the ""aquula"" (Latin, ""a little stream"", dim. of ""aqua"", ""water"") or ""crystalline lens"". The lens is part of the anterior segment of the human eye. In front of the lens is the iris, which regulates the amount of light entering into the eye. The lens is suspended in place by the suspensory ligament of the lens, a ring of fibrous tissue that attaches to the lens at its equator and connects it to the ciliary body. Posterior to the lens is the vitreous body, which, along with the aqueous humor on the anterior surface, bathes the lens. The lens"
"Scleritis 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 (the most common), nodular scleritis, and necrotizing scleritis (the most severe). Scleritis may be the first symptom of onset of connective tissue disease. Episcleritis is inflammation of the episclera, a less serious condition that seldom develops into scleritis. Symptoms of scleritis include: The pain of episcleritis is less severe than in"
"Iris (anatomy) In humans and most mammals and birds, the iris (plural: irides or irises) is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. The iris consists of two layers: the front pigmented layer known as a stroma and, beneath the stroma, pigmented epithelial cells. The stroma connects to a sphincter muscle (sphincter pupillae), which contracts the pupil"
"restore the appearance and, to some extent the function, of a damaged or missing iris. A scleral lens is a large, firm, oxygen permeable contact lens that rests on the sclera and creates a tear-filled vault over the cornea. The cause of this unique positioning is usually relevant to a specific patient whose cornea is too sensitive to support the lens directly. Scleral lenses may be used to improve vision and reduce pain and light sensitivity for people suffering from a growing number of disorders or injuries to the eye, such as severe dry eye syndrome (Kerotanconjuctivis sicca), microphthalmia, keratoconus,"
"Lamina cribrosa sclerae The nerve fibers forming the optic nerve exit the eye posteriorly through a hole in the sclera that is occupied by a mesh-like structure called the lamina cribrosa. It is formed by a multilayered network of collagen fibers that insert into the scleral canal wall. The nerve fibers that comprise the optic nerve run through pores formed by these collagen beams. In humans, a central retinal artery is located slightly off-center in nasal direction. The lamina cribrosa is thought to help maintain the pressure gradient between the inside of the eye and the surrounding tissue. Being structurally"
"the eye slightly outward to the rear margin of the cephalon (a state called opisthoparian) opposite the base of the pleural spines. From the front of the eye the suture describes a slight S-curve forward cutting the front margin in front of the eye. The central raised area of the cephalon (or glabella) is divided in the occipital ring furthest to the back, followed by the first lobe that is, like the occipital ring, defined by a furrow across the midline and two more lobes that have furrows that do not connect across the midline. The frontal lobe is the"
"Orbital septum The orbital septum (Palpebral fascia) is a membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids. In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate. When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the medial palpebral ligament, attaches to the lacrimal bone at its posterior crest. The"
"complications in the eye. Smoking tobacco delays the response to treatment in patients with episcleritis. Episcleritis is a common disease, and its exact prevalence and incidence are unknown. It typically affects young adults, and may be more common in women. 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. There are"
"Scleral lens A scleral lens, also known as a scleral contact lens and ocular surface prostheses is a large contact lens that rests on the sclera and creates a tear-filled vault over the cornea. Scleral lenses are designed to treat a variety of eye conditions, many of which do not respond to other forms of treatment. Scleral lenses may be used to improve vision and reduce pain and light sensitivity for people suffering from a growing number of disorders or injuries to the eye, such as severe dry eye syndrome, microphthalmia, keratoconus, corneal ectasia, Stevens–Johnson syndrome, Sjögren's syndrome, aniridia, neurotrophic"
"of too much aqueous humor, or reabsorption that occurs too slowly, can lead to increases in the pressure within the eye. Pars plicata The pars plicata (Latin: folded portion) is the folded and most anterior portion of the ciliary body of an eye. The ciliary body is a part of the uvea, one of the three layers that comprise the eye. The pars plicata is located anterior to the pars plana portion of the ciliary body, and posterior to the iris. The lens zonules that are used to control accommodation are attached to the pars plicata. The pars plicata is"
"Scotoma A scotoma (Greek σκότος/""skótos"", ""darkness""; plural: ""scotomas"" or ""scotomata"") is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision. Every normal mammal eye has a scotoma in its field of vision, usually termed its blind spot. This is a location with no photoreceptor cells, where the retinal ganglion cell axons that compose the optic nerve exit the retina. This location is called the optic disc. There is no direct conscious awareness of visual scotomas."
"be capable of making one cadaver-donor's corneal cells be expanded and be usable in more than one patient's eye. Cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea, with the anterior chamber and lens, refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK. While the cornea contributes most of the eye's focusing power, its focus is fixed. Accommodation (the"
"Pars plicata The pars plicata (Latin: folded portion) is the folded and most anterior portion of the ciliary body of an eye. The ciliary body is a part of the uvea, one of the three layers that comprise the eye. The pars plicata is located anterior to the pars plana portion of the ciliary body, and posterior to the iris. The lens zonules that are used to control accommodation are attached to the pars plicata. The pars plicata is the portion of the ciliary body that is responsible for producing aqueous humor, the fluid of the anterior chamber. The production"
"surface projects as the dilator muscles. The high pigment content blocks light from passing through the iris to the retina, restricting it to the pupil. The outer edge of the iris, known as the root, is attached to the sclera and the anterior ciliary body. The iris and ciliary body together are known as the anterior uvea. Just in front of the root of the iris is the region referred to as the trabecular meshwork, through which the aqueous humour constantly drains out of the eye, with the result that diseases of the iris often have important effects on intraocular"
"section is devoted to eye diseases. The pre-Hippocratics largely based their anatomical conceptions of the eye on speculation, rather than empiricism. They recognized the sclera and transparent cornea running flushly as the outer coating of the eye, with an inner layer with pupil, and a fluid at the centre. It was believed, by Alcamaeon (5th century BC) and others, that this fluid was the medium of vision and flowed from the eye to the brain by a tube. Aristotle advanced such ideas with empiricism. He dissected the eyes of animals, and discovering three layers (not two), found that the fluid"
"Sclerocornea Sclerocornea is a congenital anomaly of the eye in which the cornea blends with sclera, having no clear-cut boundary. The extent of the resulting opacity varies from peripheral to total (""sclerocornea totalis""). The severe form is thought to be inherited in an autosomal recessive manner, but there may be another, milder form that is expressed in a dominant fashion. In some cases the patients also have abnormalities beyond the eye (systemic), such as limb deformities and craniofacial and genitourinary defects. According to one tissue analysis performed after corneal transplantation, the sulfation pattern of keratan sulfate proteoglycans in the affected"