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Anterior Chamber Angle
The anterior chamber angle is a part of the eye located between the cornea and iris which contains the trabecular meshwork. The size of this angle is an important determinant of the rate aqueous humour flows out of the eye, and thus, the intraocular pressure. The anterior chamber angle is the structure which determines the anterior chamber depth. An extremely narrow anterior chamber angle is a feature of angle closure glaucoma. Additional images File:Anterior chamber angle - 3D motion parallax.gif, Gonioscopy of the anterior chamber angle File:Kammerwinkel.jpg, Gonioscopy of the anterior chamber angle. Labeled structures: 1. Schwalbe's line, 2. Trabecular meshwork (TM), 3. Scleral spur, 4. Ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliary ..., 5. Iris See also * Van ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea Refraction, refracts light, 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 (optics), focus is fixed. Accommodation (eye), Accommodation (the refocusing of light to better view near objects) is accomplished by changing the geometry of the lens. Medical terms related to the cornea often start with the prefix "''wikt:kerat-, kerat-''" from the Ancient Greek, Greek word κέρας, ''horn''. Structure The cornea has myelinated, unmyelinated nerve endings sensitive to touch, temperature and chemicals; a to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iris (anatomy)
The iris (: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm (optics), diaphragm. Eye color is defined by the iris. Etymology The word "iris" is derived from the Greek word for "rainbow", also Iris (mythology), its goddess plus messenger of the gods in the ''Iliad'', because of the many eye color, colours of this eye part. Structure The iris consists of two layers: the front pigmented Wikt:fibrovascular, fibrovascular layer known as a stroma of iris, stroma and, behind the stroma, pigmented epithelial cells. The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trabecular Meshwork
The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the eye covered by the cornea). The tissue is spongy and lined by trabeculocytes; it allows fluid to drain into a set of tubes called Schlemm's canal which is lined by endothelium with blood and lymphatic properties that allow aqueous humor to flow into the blood system. Structure The meshwork is divided up into three parts, with characteristically different ultrastructures: #''Inner uveal meshwork'' - Closest to the anterior chamber angle, contains thin cord-like trabeculae, orientated predominantly in a radial fashion, enclosing trabeculae spaces larger than the corneoscleral meshwork. #''Corneoscleral meshwork'' - Contains a large amount of elastin, arranged as a series of thin, flat, perforated sheets arranged in a laminar pattern; c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Humour
The aqueous humour is a transparent water-like fluid similar to blood plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posterior chambers of the eye, and is not to be confused with the vitreous humour, which is located in the space between the lens and the retina, also known as the posterior cavity or vitreous chamber. Blood cannot normally enter the eyeball. Structure Composition * Amino acids: transported by ciliary muscles * 98% water * Electrolytes ( pH = 7.4 -one source gives 7.1) ** Sodium = 142.09 ** Potassium = 2.2 - 4.0 ** Calcium = 1.8 ** Magnesium = 1.1 ** Chloride = 131.6 ** HCO3− = 20.15 ** Phosphate = 0.62 ** Osm = 304 * Ascorbic acid * Glutathione * Immunoglobulins Function * Maintains the intraocular pressure and inflates the globe of the eye. It is this hydrostatic pressure that keeps the eyeball in a roughly spherical shape and keeps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraocular Pressure
Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated to measure pressure in millimeters of mercury (mmHg). Physiology Intraocular pressure is determined by the production and drainage of aqueous humour by the ciliary body and its drainage via the trabecular meshwork and uveoscleral outflow. The reason for this is because the vitreous humour in the posterior segment has a relatively fixed volume and thus does not affect intraocular pressure regulation. An important quantitative relationship (Goldmann's equation) is as follows: :P_o = \frac + P_v Where: * P_o is the IOP in millimeters of mercury (mmHg) * F the rate of aqueous humour formation in microliters per minute (μL/min) * U the resorption of aqueous humour through the uveoscleral route (μL/min) * C is the facility of outflow in mic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Chamber Depth
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, ''Terminologia Anato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Closure Glaucoma
Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. A major risk factor for glaucoma is increased pressure within the eye, known as intraocular pressure (IOP). It is associated with old age, a family history of glaucoma, and certain medical conditions or the use of some medications. The word ''glaucoma'' comes from the Ancient Greek word (), meaning 'gleaming, blue-green, gray'. Of the different types of glaucoma, the most common are called open-angle glaucoma and closed-angle glaucoma. Inside the eye, a liquid called aqueous humor helps to maintain shape and provides nutrients. The aqueous humor normally drains through the trabecular meshwork. In open-angle glaucoma, the draining is impeded, causing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonioscopy
In ophthalmology, gonioscopy is a routine procedure that measures the angle between the iris (anatomy), iris and the cornea (the iridocorneal angle), using a goniolens (also known as a gonioscope) together with a slit lamp or operating microscope. Its use is important in diagnosing and monitoring various eye conditions associated with glaucoma. The goniolens or gonioscope The goniolens allows the clinician - usually an ophthalmologist or optometrist - to view the irideocorneal angle through a mirror or prism, without which the angle is masked by total internal reflection from the ocular tissue. The mechanism for this process varies with each type of goniolens. Three examples of goniolenses are the: * Koeppe direct goniolens: this transparent device is placed directly on the cornea along with lubricating fluid (to avoid damaging its surface). The steeper curvature of this goniolens' exterior surface optically eliminates the total internal reflection problem and allows a view o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schwalbe's Line
Schwalbe's line is the anatomical line found on the interior surface of the eye's cornea, and delineates the outer limit of the corneal endothelium layer. Specifically, it represents the termination of Descemet's membrane. In many cases it can be seen via gonioscopy In ophthalmology, gonioscopy is a routine procedure that measures the angle between the iris (anatomy), iris and the cornea (the iridocorneal angle), using a goniolens (also known as a gonioscope) together with a slit lamp or operating microscope .... Some evidence suggests that the corneal endothelium actually possesses stem cells that can produce endothelial cells, especially after injury, albeit on a limited scale. References Human eye anatomy {{Eye-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trabecular Meshwork
The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the eye covered by the cornea). The tissue is spongy and lined by trabeculocytes; it allows fluid to drain into a set of tubes called Schlemm's canal which is lined by endothelium with blood and lymphatic properties that allow aqueous humor to flow into the blood system. Structure The meshwork is divided up into three parts, with characteristically different ultrastructures: #''Inner uveal meshwork'' - Closest to the anterior chamber angle, contains thin cord-like trabeculae, orientated predominantly in a radial fashion, enclosing trabeculae spaces larger than the corneoscleral meshwork. #''Corneoscleral meshwork'' - Contains a large amount of elastin, arranged as a series of thin, flat, perforated sheets arranged in a laminar pattern; c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scleral Spur
The scleral spur in the visual system is a protrusion of the sclera (the white of the eye) into the anterior chamber. The spur is an annular structure composed of collagen in the human eye. It is the origin of the longitudinal and circular fibres (which swerve acutely from the spur to run circumferentially, as a sphincter near the periphery of the lens) of the ciliary muscle, and is attached posteriorly to the trabecular meshwork. Role in treatment of Glaucoma Open-angle glaucoma (OAG) and closed-angle glaucoma (CAG) may be treated by muscarinic receptor agonists (e.g., pilocarpine), which cause rapid miosis and contraction of the ciliary muscles, this pulls the scleral spur and results in the trabecular meshwork being stretched and separated. This opens the fluid pathways, and facilitates drainage of the aqueous humour, into the canal of Schlemm and ultimately results in decreasing of the intraocular pressure.Neal, M. J. (2004). "Medical Pharmacology at a Glance" (6th edition). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciliary Body
The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliary body. The ciliary body is part of the uvea, the layer of tissue that delivers oxygen and nutrients to the eye tissues. The ciliary body joins the ora serrata of the choroid to the root of the iris.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. Structure The ciliary body is a ring-shaped thickening of tissue inside the eye that divides the posterior chamber from the vitreous body. It contains the ciliary muscle, vessels, and fibrous connective tissue. Folds on the inner ciliary epithelium are called ciliary processes, and these secrete aqueous humor into the posterior chamber. The aqueous humor then flows through the iris into the anterior chamber. The ciliary bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
