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Moore's Lightning Streaks
Moore's lightning streaks are lightning type streaks (photopsia) (seen to the temporal side) due to sudden head or eye movement in the dark. They are generally caused by shock waves in the vitreous humor hitting the retina or traction on the retina from fibers in the vitreous humor. The implication is that the vitreous is softer than normal, generally this is not a cause for alarm provided they are momentary, occur only in the dark, are due to sudden head movements (acceleration) and do not occur along with many new tiny black floating specks in the vision. Professional advice should be sought in cases of doubt, as retinal detachment, a serious condition, also can cause flashes in the eye. They are named after Robert Foster Moore (1878–1963), a British ophthalmologist Ophthalmology ( ) is a surgery, surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in med ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightning
Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or with one on the ground, temporarily neutralize themselves, causing the instantaneous release of an average of one gigajoule of energy. This discharge may produce a wide range of electromagnetic radiation, from heat created by the rapid movement of electrons, to brilliant flashes of visible light in the form of black-body radiation. Lightning causes thunder, a sound from the shock wave which develops as gases in the vicinity of the discharge experience a sudden increase in pressure. Lightning occurs commonly during thunderstorms as well as other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions. The three main kinds of lightning are distinguished by where they occur: either inside a single thundercloud (intra-cloud), between two clouds (cloud-to-cloud), or between a cloud and the ground ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photopsia
Photopsia is the presence of perceived flashes of light in the field of vision. It is most commonly associated with: * posterior vitreous detachment * migraine aura (ocular migraine / retinal migraine) * migraine aura without headache * scintillating scotoma * retinal break or detachment * occipital lobe infarction (similar to occipital stroke) * sensory deprivation (ophthalmopathic hallucinations) * age-related macular degeneration * vertebrobasilar insufficiency * optic neuritis * visual snow syndrome Vitreous shrinkage or liquefaction, which are the most common causes of photopsia, cause a pull in vitreoretinal attachments, irritating the retina and causing it to discharge electrical impulses. These impulses are interpreted by the brain as flashes. This condition has also been identified as a common initial symptom of punctate inner choroiditis ( PIC), a rare retinal autoimmune disease believed to be caused by the immune system mistakenly attacking and destro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temple (anatomy)
The temple is a latch where four skull bones fuse: the frontal, parietal, temporal, and sphenoid. It is located on the side of the head behind the eye between the forehead and the ear. The temporal muscle covers this area and is used during mastication. Cladists classify land vertebrates based on the presence of an upper hole, a lower hole, both, or neither in the cover of dermal bone that formerly covered the temporalis muscle, whose origin is the temple and whose insertion is the jaw. The brain has a lobe called the temporal lobe. Etymology The word "templar" as used in anatomy has a separate etymology from the other meaning of word ''temple'', meaning "place of worship". Both come from Latin, but the word for the place of worship comes from ', whereas the word for the part of the head comes from Vulgar Latin *', modified from ', plural form ("both temples") of ', a word that meant both "time" and the part of the head. Due to the common source with the word for ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Waves
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitreous Humor
The vitreous body (''vitreous'' meaning "glass-like"; , ) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates. It is often referred to as the vitreous humor (also spelled humour, from Latin meaning liquid) or simply "the vitreous". Vitreous fluid or "liquid vitreous" is the liquid component of the vitreous gel, found after a vitreous detachment. It is not to be confused with the aqueous humor, the other fluid in the eye that is found between the cornea and lens. Structure The vitreous humor is a transparent, colorless, gelatinous mass that fills the space in the eye between the lens and the retina. It is surrounded by a layer of collagen called the vitreous membrane (or hyaloid membrane or vitreous cortex) separating it from the rest of the eye. It makes up four-fifths of the volume of the eyeball. The vitreous humour is fluid-like near the centre, and gel-like near the edges. The vitreo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as well as high-acuity vision used f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass. The SI unit for acceleration is metre per second squared (, \mathrm). For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal Detachment
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a surgical emergency. The retina is a thin layer of light-sensitive tissue on the back wall of the eye. The optical system of the eye focuses light on the retina much like light is focused on the film in a camera. The retina translates that focused image into neural impulses and sends them to the brain via the optic nerve. Occasionally, posterior vitreous detachment, injury or trauma to the eye or head may cause a small tear in the retina. The tear allows vitreous fluid to seep through it under the retina, and peel it away like a bubble in wallpaper. Diagnosis Symptoms As the retina is responsible for vision, persons experiencing a retinal detachment have vision loss. This can be painful or painless. Imaging Ultrasou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many List of islands of the United Kingdom, smaller islands within the British Isles. Northern Ireland shares Republic of Ireland–United Kingdom border, a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is , with an estimated 2020 population of more than 67 million people. The United Kingdom has evolved from a series of annexations, unions and separations of constituent countries over several hundred years. The Treaty of Union between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmologist
Ophthalmology ( ) is a surgery, surgical subspecialty within medicine that deals with the diagnosis and treatment of eye 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 (medicine), residency training specific to that field. This may include a one-year integrated internship that involves more general medical training in other fields such as internal medicine or general surgery. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat 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 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Diseases
This is a partial list of human eye diseases and disorders. The World Health Organization publishes a classification of known diseases and injuries, the International Statistical Classification of Diseases and Related Health Problems, or ICD-10. This list uses that classification. H00-H06 Disorders of eyelid, lacrimal system and orbit * (H02.1) Ectropion * (H02.2) Lagophthalmos * (H02.3) Blepharochalasis * (H02.4) Ptosis * (H02.5) Stye, an acne type infection of the sebaceous glands on or near the eyelid. * (H02.6) Xanthelasma of eyelid * (H03.0*) Parasitic infestation of eyelid in diseases classified elsewhere ** Dermatitis of eyelid due to Demodex species ( B88.0+ ) ** Parasitic infestation of eyelid in: *** leishmaniasis ( B55.-+ ) *** loiasis ( B74.3+ ) *** onchocerciasis ( B73+ ) *** phthiriasis ( B85.3+ ) * (H03.1*) Involvement of eyelid in other infectious diseases classified elsewhere ** Involvement of eyelid in: *** herpesviral (herpes simplex) infection ( B00. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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