Ophthalmology Ophthalmology A-scan ultrasound biometry, commonly referred to as an A-scan, is routine type of diagnostic test used in ophthalmology. The A-scan provides data on the shape of the eye, which is a major determinant in common sight disorders. Instruments used in this type of test require direct contact with the cornea, however a non-contact instrument has been reported. Disposable covers, which come in actual contact with the eye, have also been evaluated. ...more on Wikipedia about "A-scan ultrasound biometry"
Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. Often used in the context of laser ablation, a process by which the molecular bonds of a material are dissolved by a laser. ...more on Wikipedia about "Ablation"
Accommodation is the process by which the eye increases optical power to maintain a clear image ( focus). ...more on Wikipedia about "Accommodation (eye)"
The accommodation reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object (and vice versa). It is dependent on cranial nerve II ( afferent limb of reflex), higher centres and cranial nerve III. ...more on Wikipedia about "Accommodation reflex"
Achromatopsia is a medical condition (also called maskun or rod monochromatism) characterized by a low cone cell count or lack of function in cone cells; these are the light receptors responsible for colour perception. It is endemic on the atoll of Pingelap and was described by Oliver Sacks in Island of the Colourblind. Sacks went there with a Norwegian who had maskun, and the book narrates his experiences on the island. ...more on Wikipedia about "Achromatopsia"
The Age-Related Eye Disease Study was a clinical trial sponsored by the National Eye Institute, one of the National Institutes of Health in the United States. The study was designed to ...more on Wikipedia about "Age-Related Eye Disease Study"
AgingEye Times is a private, not-for-profit, organization that provides free access to the latest medical information on diseases of the aging eye in an attempt to empower people to take control of their vision health, while educating them on the importance and need for further medical advances. AgingEye Times aim is to provide evidence-based medical information by careful analysis of the data in published journal articles. ...more on Wikipedia about "AgingEye Times"
Alice in Wonderland syndrome (AIWS), or micropsia, is a disorienting neurological condition which affects human visual perception. ...more on Wikipedia about "Alice in Wonderland syndrome"
Allergic conjunctivitis is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergens differ between patients, the most common cause is hay fever. Symptoms consist of redness (mainly due to vasodilation of the peripheral small blood vessels), itching and increased lacrimation (production of tears). ...more on Wikipedia about "Allergic conjunctivitis"
Amaurosis (Greek meaning darkening, dark, or obscure) is vision loss or weakness that occurs without an apparent lesion affecting the eye ** . It may result from either a medical condition of from excess acceleration, as in flight. The term is the same as the Latin gutta serena. ...more on Wikipedia about "Amaurosis"
Amaurosis fugax (Greek: fugax meaning fugitive, amaurosis meaning darkening, dark, or obscure) is a painless, temporary loss of vision in one eye caused by decreased blood flow ( ischemia) to the retina. It is a type of transient ischaemic attack (TIA). The lack of blood flow can be caused by emboli (moving clots) obstructing blood flow in the retinal artery or ophthalmic artery. The most common causes are a clot of plaque or a blood clot from a stenosed carotid artery, other sources are heart or heart valves and arterial spasm. Vision loss lasts for the period of time the clot obstructs blood flow. ...more on Wikipedia about "Amaurosis fugax"
Amblyopia, or lazy eye, is a disorder of the eyes. It is characterised by poor or blurry vision that is not correctable with glasses in an eye that is otherwise physically healthy and normal. The problem is due to either no transmission or poor transmission of the visual image to the brain for a sustained period of dysfunction or disuse during early childhood. The condition will only arise at this young age because most of the visual system's development in humans is complete and "locked in" by a few years of age. Amblyopia normally only affects one eye, but it is possible to be amblyopic in both eyes if both are similarly deprived of a good, clear visual image. ...more on Wikipedia about "Amblyopia"
Amplitude of accommodation (AA) is a measurement of the eye’s ability to focus clearly on objects at near distances (i.e. accommodation). This eye focusing range for a child is usually about 2-3 inches. For a young adult, it is 4-6 inches. The focus range for a 45-year-old adult is about 20 inches. For an 80-year-old adult, it is 60 inches. ** . ...more on Wikipedia about "Amplitude of accommodation"
The Amsler grid, used since 1945, is a grid of horizontal and vertical lines used to monitor a person's central visual field. It is a diagnostic tool that aids in the detection of visual disturbances caused by changes in the retina, particularly the macula (e.g. macular degeneration), as well as the optic nerve and the visual pathway to the brain. ...more on Wikipedia about "Amsler grid" Are you ready for http://www.shortopedia.com?
Aniridia is a rare congenital eye condition characterized by the underdevelopment or even absence of the iris of the human eye. This usually occurs in both eyes. It is associated with poor development of the retina at the back of the eye, and this causes loss of vision. ...more on Wikipedia about "Aniridia"
Anisocoria is a condition characterized by an unequal size of the pupils. ...more on Wikipedia about "Anisocoria"
Anisometropia is the condition in which the two eyes have unequal refractive power; that is, are in different states of myopia (nearsightedness) or hyperopia (farsightedness). ...more on Wikipedia about "Anisometropia"
Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision due to damage to the optic nerve from insufficient blood supply. ...more on Wikipedia about "Anterior ischemic optic neuropathy"
Aphakia is the absence of the lens of the eye, due to surgical removal, perforating wound or ulcer, or congenital anomaly; causes a loss of accommodation, hyperopia, and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma. ...more on Wikipedia about "Aphakia"
Arc eye, also known as arc flash or welder's flash or corneal flash burns, is a painful condition sometimes experienced by welders who have failed to use adequate eye protection. It can also occur due to light from sunbeds, light reflected from snow (known as snow blindness), water or sand. The intense ultraviolet light emitted by the arc causes a superficial and painful keratitis. ...more on Wikipedia about "Arc eye"
Argyll Robertson pupils are small, unequal, irregularly shaped pupils that constrict with accommodation but do not react normally to light. This means that while the eyes can focus on objects both near and far, the direct and consensual response to light are reduced or absent. These are usually, but not always caused by central nervous system complications of syphilis. ...more on Wikipedia about "Argyll Robertson pupil"
Asthenopia is an ophthalmological condition that manifests itself through unspecific symptoms such as fatigue, eye strain, pain in or around the eyes, blurred vision, headache and occasional double vision. Symptoms often occur after reading, computer work, or other activities that involve tedious visual tasks. Sometimes, asthenopia can be traced back to specific eye problems, such as uncorrected refraction errors or heterophoria. ...more on Wikipedia about "Asthenopia"
In optics, astigmatism is a monochromatic aberration in which an optical system has different focal planes for rays in different planes. Lenses and mirrors which are partly cylindrical show this behaviour already for on-axis rays, parabolic mirrors and uncorrected lens systems only proportional to the squared angle between rays and optical axis. Optical systems which are corrected to have no, or only higher order, astigmatism are called anastigmats. ...more on Wikipedia about "Astigmatism"
An automated refractor, or autorefractor, is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or contact lenses. This is achieved by measuring how light is changed as it enters a person's eye. ...more on Wikipedia about "Automated refractor"
B-scan ultrasonography, or B-scan, is a diagnostic test used in ophthalmology to produce a two-dimensional, cross-sectional view of the eye and the orbit. ...more on Wikipedia about "B-scan ultrasonography" Connect with www.shortopedia.com. shortopedia
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