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Confrontation Visual Field Testing
Confrontation visual field testing is a test used in ophthalmology for rapid and gross detection of large-scale visual field problems. It is done by asking the patient to look directly at the examiner's eye or nose and compare the patient's visual field with the examiner's field. It can be used to test the binocular visual field (with both eyes open) and or the visual field of each eye separately (with one eye closed). Indications Confrontation visual field testing is an important part of a routine ophthalmological or neurological examination. It can be used for rapid and gross assessment of large-scale visual field problems due to ophthalmological or neurological diseases, such as homonymous and heteronymous hemianopias, quadranopsia, altitudinal visual loss, central/centrocecal scotoma etc. Test using a red target can detect red-desaturation, a sign of early optic nerve disease. Procedure Confrontation visual field testing does not need a clinical setting to perform. It can be d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Field
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.Strasburger, Hans; Pöppel, Ernst (2002). Visual Field. In G. Adelman & B.H. Smith (Eds): ''Encyclopedia of Neuroscience''; 3rd edition, on CD-ROM. Elsevier Science B.V., Amsterdam, New York. However, the visual field can also be understood as a predominantly ''perceptual'' concept and its definition then becomes that of the "spatial array of visual sensations available to observation in introspectionist psychological experiments" (for example in van Doorn et al., 2013). The corresponding concept for optical instruments and image sensors is the field of view (FOV). In humans and animals, the FOV refers to the area visible when eye mov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmology
Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. In the United States, following graduation from medical school, one must complete a four-year residency in ophthalmology to become an ophthalmologist. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat ailments, such as eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care—medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homonymous Hemianopsia
Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual pathways for the left hemifield of both eyes, and the left half of the brain has visual pathways for the right hemifield of both eyes. When one of these pathways is damaged, the corresponding visual field is lost. Signs and symptoms Paris as seen with right homonymous hemianopsia Mobility can be difficult for people with homonymous hemianopsia. "Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs." People with homonymous hemianopsia often experience discomfort in crowds. "A patient with this condition may be unaware of what he or she cannot see and frequently bumps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadranopsia
Hemianopsia, or hemianopia, is a loss of vision or blindness ( anopsia) in half the visual field, usually on one side of the vertical midline. The most common causes of this damage are stroke, brain tumor, and trauma. This article deals only with permanent hemianopsia, and not with transitory or temporary hemianopsia, as identified by William Wollaston PRS in 1824. Temporary hemianopsia can occur in the aura phase of migraine. Etymology The word ''hemianopsia'' is from Greek origins, where: * ''hemi'' means "half", * ''an'' means "without", and * ''opsia'' means "seeing". Types When the pathology involves both eyes, it is either homonymous or heteronymous. Homonymous hemianopsia Paris as seen with left homonymous hemianopsia A homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes. The visual images that we see to the right side travel from both eyes to the left side of the brain, while the visual images we see to the left side i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotoma
A scotoma 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 mammalian 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. They are simply regions of reduced information within the visual field. Rather than recognizing an incomplete image, patients with scotomas report that things "disappear" on them. The presence of the blind spot scotoma can be demonstrated subjectively by covering one eye, carefully holding fixation with the open eye, and placing an object (such as one's thumb) in the lateral and horizontal visual field, about 15 degrees from fixati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Nerve
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, Pretectal area, pretectal nuclei, and superior colliculus. Structure The optic nerve has been classified as the second of twelve paired cranial nerves, but it is technically a myelinated tract of the central nervous system, rather than a classical nerve of the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoplasm
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, which may be called a tumour or tumor.'' ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior. Malignant neoplasms are also simply known as cancers and are the focus of oncology. Prior to the abnormal growth of tissue, such as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia does not always progress to neoplasia and can occur in other conditions as well. The word neoplasm is from Ancient Greek 'new' and 'formation, creation'. Types A neoplasm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, 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 humour, aqueous humor helps to maintain shape and provides nutrients. The aqueous humor normally drains through the trabecular meshwork. In open-angle glaucoma, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Neuropathy
Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain. Damage and death of these nerve cells, or neurons, leads to characteristic features of optic neuropathy. The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. A pale disc is characteristic of long-standing optic neuropathy. In many cases, only one eye is affected and a person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. Optic neuropathy is often called optic atrophy, to describe the loss of some or most of the fibers of the optic nerve. Signs and symptoms The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. In many cases, only one eye is affected and the person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. People may also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diagnostic Ophthalmology
Diagnosis (: diagnoses) is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in a lot of different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions. Computer science and networking * Bayesian network * Complex event processing * Diagnosis (artificial intelligence) * Event correlation * Fault management * Fault tree analysis * Grey problem * RPR problem diagnosis * Remote diagnostics * Root cause analysis * Troubleshooting * Unified Diagnostic Services Mathematics and logic * Bayesian probability * Block Hackam's dictum * Occam's razor * Regression diagnostics * Sutton's law Medicine * Medical diagnosis * Molecular diagnostics Methods * CDR computerized assessment system * Computer-aided diagnosis * Differential diagnosis * Retrospective ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
