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Brock String
A Brock string (named after Frederick W. Brock) is an instrument used in vision therapy. It consists of a white string of approximately 10 feet in length with three small wooden beads of different colors. The Brock string is commonly employed during treatment of convergence insufficiency and other anomalies of binocular vision. It is used to develop skills of convergence as well as to disrupt suppression of one of the eyes. During therapy, the one end of the Brock string is held on the tip of the nose while the other is tied to a fixed point. The three beads are spaced out at various distances. The patient is asked to focus on one of the beads, while noting the visual input of each eye and sensation of convergence. The patient can use variable techniques to make easier or more difficult by bringing the beads closer\further to the nose and by employing lenses and prisms. Although this procedure is usually associated with binocular vision and anti-suppression therapy, it can also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brock String
A Brock string (named after Frederick W. Brock) is an instrument used in vision therapy. It consists of a white string of approximately 10 feet in length with three small wooden beads of different colors. The Brock string is commonly employed during treatment of convergence insufficiency and other anomalies of binocular vision. It is used to develop skills of convergence as well as to disrupt suppression of one of the eyes. During therapy, the one end of the Brock string is held on the tip of the nose while the other is tied to a fixed point. The three beads are spaced out at various distances. The patient is asked to focus on one of the beads, while noting the visual input of each eye and sensation of convergence. The patient can use variable techniques to make easier or more difficult by bringing the beads closer\further to the nose and by employing lenses and prisms. Although this procedure is usually associated with binocular vision and anti-suppression therapy, it can also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frederick W
Frederick may refer to: People * Frederick (given name), the name Nobility Anhalt-Harzgerode *Frederick, Prince of Anhalt-Harzgerode (1613–1670) Austria * Frederick I, Duke of Austria (Babenberg), Duke of Austria from 1195 to 1198 * Frederick II, Duke of Austria (1219–1246), last Duke of Austria from the Babenberg dynasty * Frederick the Fair (Frederick I of Austria (Habsburg), 1286–1330), Duke of Austria and King of the Romans Baden * Frederick I, Grand Duke of Baden (1826–1907), Grand Duke of Baden * Frederick II, Grand Duke of Baden (1857–1928), Grand Duke of Baden Bohemia * Frederick, Duke of Bohemia (died 1189), Duke of Olomouc and Bohemia Britain * Frederick, Prince of Wales (1707–1751), eldest son of King George II of Great Britain Brandenburg/Prussia * Frederick I, Elector of Brandenburg (1371–1440), also known as Frederick VI, Burgrave of Nuremberg * Frederick II, Elector of Brandenburg (1413–1470), Margrave of Brandenburg * Frederick William, Elector ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vision Therapy
Vision therapy (VT), or behavioral optometry, is an umbrella term for alternative medicine treatments using eye exercises, based around the pseudoscientific claim that vision problems are the true underlying cause of learning disabilities, particularly in children. Vision therapy has not been shown to be effective using scientific studies, except for helping with convergence insufficiency. Most claimsfor example that the therapy can address neurological, educational, and spatial difficultieslack supporting evidence. Neither the American Academy of Pediatrics nor the American Academy of Ophthalmology support the use of vision therapy. Definition and conceptual basis Vision therapy is based on the proposition that many learning disabilities in children are based on vision problems, and that these can be cured by performing eye exercises. Vision therapy lacks sound evidence, has been characterized as a pseudoscience and its practice as quackery. Vision therapy is a broad concept t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergence Insufficiency
Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence. Symptoms The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation, among others. In some cases, difficulty with making eye contact have been noted as a complaint amongst those affected. Note that some Internet resources confuse convergence and divergence dysfunction, reversing them. Diagnosis Diagnosis of convergence insufficiency is made by an eye care professional skilled in binocular vision dysfunctions, such as an orthoptist, to rule out any organic disease. Convergence insufficiency is chara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binocular Vision
In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an animal has eyes on opposite sides of its head and shares no field of view between them, like in some animals. Neurological researcher Manfred Fahle has stated six specific advantages of having two eyes rather than just one: #It gives a creature a "spare eye" in case one is damaged. #It gives a wider field of view. For example, humans have a maximum horizontal field of view of approximately 190 degrees with two eyes, approximately 120 degrees of which makes up the binocular field of view (seen by both eyes) flanked by two uniocular fields (seen by only one eye) of approximately 40 degrees. #It can give stereopsis in which binocular disparity (or parallax) provided by the two eyes' different positions on the head gives precise depth per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergence (eye)
A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision. When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the projection of the image is in the centre of the retina in both eyes. To look at an object closer by, the eyes rotate towards each other (convergence), while for an object farther away they rotate away from each other (divergence). Exaggerated convergence is called ''cross eyed viewing'' (focusing on the nose for example). When looking into the distance, the eyes diverge until parallel, effectively fixating the same point at infinity (or very far away). Vergence movements are closely connected to accommodation of the eye. Under normal visual conditions, looking at an object at a different distance will automatically cause changes in both vergence and accommodation, sometimes known as the '' accommodation-convergence reflex''. When under non-typi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suppression (eye)
Suppression of an eye is a subconscious adaptation by a person's brain to eliminate the symptoms of disorders of binocular vision such as strabismus, convergence insufficiency and aniseikonia. The brain can eliminate double vision by ignoring all or part of the image of one of the eyes. The area of a person's visual field that is suppressed is called the suppression scotoma (with a scotoma meaning, more generally, an area of partial alteration in the visual field). Suppression can lead to amblyopia. Effect Nobel-prize winner David H. Hubel described suppression in simple terms as follows: :"Suppression is familiar to anyone who has trained himself to look through a monocular microscope, sight a gun, or do any other strictly one-eye task, with the other eye open. The scene simply disappears for the suppressed eye."David H. Hubel: ''Eye, Brain, and Vision'', Chapter 9 "Deprivation and development"section "Strabismus" Published online by Harvard Medical School (downloaded 30 Septemb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lentil plant), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism (optics)
An optical prism is a transparent optics, optical element with flat, polished surfaces that are designed to refraction, refract light. At least one surface must be angled — elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are prism (geometry), geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic glass, acrylic and fluorite#Optics, fluorite. A dispersive prism can be used to break white#White light, white light up into its constituent spectral colors (the colors of the rainbow) as described in the following section. Other types of prisms noted below can be used to reflection (physics), reflect light, or to split light into components with different polarization (w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplopia
Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occurring involuntarily, it results in impaired function of the extraocular muscles, where both eyes are still functional, but they cannot turn to target the desired object. Problems with these muscles may be due to mechanical problems, disorders of the neuromuscular junction, disorders of the cranial nerves ( III, IV, and VI) that innervate the muscles, and occasionally disorders involving the supranuclear oculomotor pathways or ingestion of toxins. Diplopia can be one of the first signs of a systemic disease, particularly to a muscular or neurological process, and it may disrupt a person's balance, movement, or reading abilities. Causes Diplopia has a diverse range of ophthalmologic, infectious, autoimmune, neu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
