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Hydrophthalmos
Buphthalmos (plural: buphthalmoses) is enlargement of the eyeball and is most commonly seen in infants and young children. It is sometimes referred to as buphthalmia (plural buphthalmias). It usually appears in the newborn period or the first 3 months of life. and in most cases indicates the presence of congenital (infantile) glaucoma, which is a disorder in which elevated pressures within the eye lead to structural eye damage and vision loss. Signs and symptoms Buphthalmos in itself is merely a clinical sign and does not generate symptoms. Patients with glaucoma often initially have no symptoms; later, they can exhibit excessive tearing (lacrimation) and extreme sensitivity to light ( photophobia). On ophthalmologic exam, a doctor can detect increased intraocular pressure, distortion of the optic disc, and corneal edema, which manifests as haziness. Other symptoms include a prominent eyeball, Haab's striae tear in the Descemet's membrane of the cornea, an enlarged cornea, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photophobia
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia. The term ''photophobia'' comes from the Greek language, Greek φῶς (''phōs''), meaning "light", and φόβος (''phóbos''), meaning "fear". Causes Patients may develop photophobia as a result of several different medical conditions, related to the human eye, eye, the nervous system, genetic, or other causes. Photophobia may manifest itself in an increased response to light starting at any step in the visual system, such as: *Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if its pupil(s) is unabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaucoma
Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye remains open, with less common types including closed-angle (narrow angle, acute congestive) glaucoma and normal-tension glaucoma. Open-angle glaucoma develops slowly over time and there is no pain. Peripheral vision may begin to decrease, followed by central vision, resulting in blindness if not treated. Closed-angle glaucoma can present gradually or suddenly. The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea. Vision loss from glaucoma, once it has occurred, is permanent. Eyes affected by glaucoma are referred to as being glaucomatous. Risk factors for glaucoma include increasing age, high pressure in the eye, a family history of glaucoma, and use of steroid medication. F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Humor
The aqueous humour is a transparent water-like fluid similar to 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 the walls of the eyeball ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blindness
Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment– visual impairment may cause the individual difficulties with normal daily tasks including reading and walking. Low vision is a functional definition of visual impairment that is chronic, uncorrectable with treatment or correctable lenses, and impacts daily living. As such low vision can be used as a disability metric and varies based on an individual's experience, environmental demands, accommodations, and access to services. The American Academy of Ophthalmology defines visual impairment as the best-corrected visual acuity of less than 20/40 in the better eye, and the World Health Organization defines it as a presenting acuity of less than 6/12 in the better eye. The term blindness is used for complete or nearly complete vision loss. In ... [...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 ( B00.5+ ) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ray Charles
Ray Charles Robinson Sr. (September 23, 1930 – June 10, 2004) was an American singer, songwriter, and pianist. He is regarded as one of the most iconic and influential singers in history, and was often referred to by contemporaries as "The Genius". Among friends and fellow musicians he preferred being called "Brother Ray". Charles was blinded during childhood, possibly due to glaucoma. Charles pioneered the soul music genre during the 1950s by combining blues, jazz, rhythm and blues, and gospel styles into the music he recorded for Atlantic Records. He contributed to the integration of country music, rhythm and blues, and pop music during the 1960s with his crossover success on ABC Records, notably with his two ''Modern Sounds'' albums. While he was with ABC, Charles became one of the first black musicians to be granted artistic control by a mainstream record company. Charles's 1960 hit "Georgia On My Mind" was the first of his three career No. 1 hits on the ''Billboard'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitreous Humour
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 vitreous h ... [...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 micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schlemm's Canal
Schlemm's canal is a circular lymphatic-like vessel in the eye. It collects aqueous humor from the anterior chamber and delivers it into the episcleral blood vessels. Canaloplasty may be used to widen it. Structure Schlemm's canal is an endothelium-lined tube, resembling that of a lymphatic vessel. On the inside of the canal, nearest to the aqueous humor, it is covered and held open by the trabecular meshwork. This creates outflow resistance against the aqueous humor. Development While Schlemm's canal has generally been considered as a vein or a scleral venous sinus, the canal is similar to the lymphatic vasculature. It is never filled with blood in physiological settings as it does not receive arterial blood circulation. Schlemm's canal displays several features of lymphatic endothelium, including the expression of PROX1, VEGFR3, CCL21, FOXC2, but lacked the expression of LYVE1 and PDPN. It develops via a unique mechanism involving the transdifferentiation of venous endotheli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iris (anatomy)
In humans and most mammals and birds, the iris (plural: ''irides'' or ''irises'') is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. Eye color is defined by the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Structure The iris consists of two layers: the front pigmented fibrovascular layer known as a stroma and, beneath 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. The sphincter pupillae is the opposing muscle of the dilator pupillae. The pupil's diameter, and thus the inner border of the iris, changes size when constricting or dilating. The outer border of the iris does not change size. The constricti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tearing
Tearing is the act of breaking apart a material by force, without the aid of a cutting tool. A tear in a piece of paper, fabric, or some other similar object may be the result of the intentional effort with one's bare hands, or be accidental. Unlike a cut, which is generally on a straight or patterned line controlled by a tool such as scissors, a tear is generally uneven and, for the most part, unplanned. An exception is a tear along a perforated line, as found on a roll of toilet paper or paper towels, which has been previously partially cut, so the effort of tearing will probably produce a straight line. Materials vary in their susceptibility to tearing. Some materials may be quite resistant to tearing when they are in their full form, but when a small cut or tear is made, the material becomes compromised, and the effort needed to continue tearing along that line becomes less. Materials can be characterized by standard test methods to measure their tear resistance. There are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea 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 is fixed. 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 "'' kerat-''" from the Greek word κέρας, ''horn''. Structure The cornea has unmyelinated nerve endings sensitive to touch, temperature and chemicals; a touch of the cornea causes an involuntary reflex to close the eyelid. Because transparency is of prime importance, the healthy cornea does not have or need blood vessels with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
