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Acute Visual Loss
Acute visual loss is a rapid loss of the ability to see. It is caused by many ocular conditions like retinal detachment, glaucoma, macular degeneration, and giant cell arteritis, etc. Main causes Retinal detachment Retinal detachment should be considered if there were preceding flashes or floaters, or if there is a new visual field defect in one eye. If treated early enough, retinal tear and detachment can have a good outcome. Glaucoma Angle-closure glaucoma should be considered if there is painful loss of vision with a red eye, nausea or vomiting. The eye pressure will be very high typically greater than 40 mmHg. Emergent laser treatment to the iris may prevent blindness. Macular degeneration Wet macular degeneration should be considered in older people with new distortion of their vision with bleeding in the macula. Vision can often be regained with prompt eye injections with anti-VEGF agents. Giant cell arteritis Giant cell arteritis should be considered in an olde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snellen Chart
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen, who developed the chart in 1862. Many ophthalmologists and vision scientists now use an improved chart known as the LogMAR chart. History Snellen developed charts using symbols based in a 5×5 unit grid. The experimental charts developed in 1861 used abstract symbols. Snellen's charts published in 1862 used alphanumeric capitals in the 5×5 grid. The original chart shows A, C, E, G, L, N, P, R, T, 5, V, Z, B, D, 4, F, H, K, O, S, 3, U, Y, A, C, E, G, L, 2. Description The normal Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, or N. Subsequent rows have increasing numbers of letters that decrease in size. A person taking the test covers one eye from 6 metres or 20 feet away, and reads aloud the letters of each row ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-VEGF Agents
Anti–vascular endothelial growth factor therapy, also known as anti-VEGF () therapy or medication, is the use of medications that block vascular endothelial growth factor. This is done in the treatment of certain cancers and in age-related macular degeneration. They can involve monoclonal antibodies such as bevacizumab, antibody derivatives such as ranibizumab (Lucentis), or orally-available small molecules that inhibit the tyrosine kinases stimulated by VEGF: sunitinib, sorafenib, axitinib, and pazopanib (some of these therapies target VEGF receptors rather than the VEGFs). Both antibody-based compounds and the first three orally available compounds are commercialized. The latter two, axitinib and pazopanib, are in clinical trials. Bergers and Hanahan concluded in 2008 that anti-VEGF drugs can show therapeutic efficacy in mouse models of cancer and in an increasing number of human cancers. But, "the benefits are at best transitory and are followed by a restoration of tumour gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branch Retinal Artery Occlusion
Branch retinal artery occlusion (BRAO) is a rare retinal vascular disorder in which one of the branches of the central retinal artery is obstructed. Presentation Abrupt painless loss of vision in the visual field corresponding to territory of the obstructed artery is the typical history of presentation. Patients can typically define the time and extent of visual loss precisely. Retinal whitening that corresponds to the area of ischemia is the most notable finding. In chronic phase the retinal whitening disappears. Risk factors Risk factors include: * Hypertension * Elevated lipid levels * cigarette smoking * Diabetes * Susac's syndrome - This is one of the key symptoms of the disease. Diagnosis Ancillary testing is not usually necessary to make the diagnosis. Fluorescein angiography reveals an abrupt diminution in dye at the site of the obstruction. Visual field testing can confirm the extent of visual loss. Treatment No proved treatment exists for branch retinal artery occl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branch Retinal Vein Occlusion
Branch retinal vein occlusion is a common retinal vascular disease of the elderly. It is caused by the occlusion of one of the branches of central retinal vein. Signs and symptoms Patients with branch retinal vein occlusion usually have a sudden onset of blurred vision or a central visual field defect. The eye examination findings of acute branch retinal vein occlusion include superficial hemorrhages, retinal edema, and often cotton-wool spots in a sector of retina drained by the affected vein. The obstructed vein is dilated and tortuous. The quadrant most commonly affected is the superotemporal (63%). Retinal neovascularization occurs in 20% of cases within the first 6–12 months of occlusion and depends on the area of retinal nonperfusion. Neovascularization is more likely to occur if more than five disc diameters of nonperfusion are present and vitreous hemorrhage can ensue. Risk factors Studies have identified the following abnormalities as risk factors for the development ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Retinal Vein Occlusion
Central retinal vein occlusion, also CRVO, is when the central retinal vein becomes occluded, usually through thrombosis. The central retinal vein is the venous equivalent of the central retinal artery and both may become occluded. Since the central retinal artery and vein are the sole source of blood supply and drainage for the retina, such occlusion can lead to severe damage to the retina and blindness, due to ischemia (restriction in blood supply) and edema (swelling). CRVO can cause ocular ischemic syndrome. Nonischemic CRVO is the milder form of the disease. It may progress to the more severe ischemic type. CRVO can also cause glaucoma. Diagnosis Despite the role of thrombosis in the development of CRVO, a systematic review found no increased prevalence of thrombophilia (an inherent propensity to thrombosis) in patients with retinal vascular occlusion. Treatment Treatment consists of Anti-VEGF drugs like Lucentis or intravitreal steroid implant (Ozurdex) and Pan-Retinal La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Retinal Artery Occlusion
Central retinal artery occlusion (CRAO) is a disease of the eye where the flow of blood through the central retinal artery is blocked (occluded). There are several different causes of this occlusion; the most common is carotid artery atherosclerosis. Signs and symptoms Central retinal artery occlusion is characterized by painless, acute vision loss in one eye. Upon fundoscopic exam, one would expect to find: cherry-red spot (90%) (a morphologic description in which the normally red background of the choroid is sharply outlined by the swollen opaque retina in the central retina), retinal opacity in the posterior pole (58%), pallor (39%), retinal arterial attenuation (32%), and optic disk edema (22%). During later stages of onset, one may also find plaques, emboli, and optic atrophy. Diagnosis One diagnostic method for the confirmation of CRAO is Fluorescein angiography, it is used to examine the retinal artery filling time after the fluorescein dye is injected into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steroids
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and as signaling molecules. Hundreds of steroids are found in plants, animals and fungi. All steroids are manufactured in cells from the sterols lanosterol ( opisthokonts) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene. The steroid core structure is typically composed of seventeen carbon atoms, bonded in four " fused" rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from cholest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jaw Claudication
Jaw claudication is pain in the jaw associated with chewing. It is a classic symptom of giant-cell arteritis, but can be confused with symptoms of temporomandibular joint disease, rheumatoid arthritis of the temporomandibular joint, myasthenia gravis, tumors of the parotid gland, or occlusion or stenosis of the external carotid artery. The term is derived by analogy from claudication of the leg, where pain is caused by arterial insufficiency Peripheral artery disease (PAD) is an abnormal narrowing of arteries other than those that supply the heart or brain. When narrowing occurs in the heart, it is called coronary artery disease, and in the brain, it is called cerebrovascular diseas .... References Symptoms Jaw disorders {{Symptom-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macula
The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. The anatomical macula at a size of is much larger than the clinical macula which, at a size of , corresponds to the anatomical fovea. The macula is responsible for the central, high-resolution, color vision that is possible in good light; and this kind of vision is impaired if the macula is damaged, for example in macular degeneration. The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The term macula lutea comes from Latin ''macula'', "spot", and ''lutea'', "yellow". Structure The macula is an oval-shaped pigmented area in the center of the retina of the human eye and other animal eyes. Its center is shifted slightly away from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vision Loss
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] |
Red Eye (medicine)
A red eye is an eye that appears red due to illness or injury. It is usually injection and prominence of the superficial blood vessels of the conjunctiva, which may be caused by disorders of these or adjacent structures. Conjunctivitis and subconjunctival hemorrhage are two of the less serious but more common causes. Management includes assessing whether emergency action (including referral) is needed, or whether treatment can be accomplished without additional resources. Slit lamp examination is invaluable in diagnosis but initial assessment can be performed using a careful history, testing vision (visual acuity), and carrying out a penlight examination. Diagnosis Particular signs and symptoms may indicate that the cause is serious and requires immediate attention. Seven such signs are: * Reduced visual acuity * Ciliary flush (circumcorneal injection) * Corneal abnormalities including edema or opacities ("corneal haze") * Corneal staining * Pupil abormalities inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Field Defect
The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point. The equivalent concept for optical instruments and image sensors is the field of view (FOV). In optometry, ophthalmology, and neurology, a visual field test is used to determine whether the visual field is affected by diseases that cause local scotoma or a more extensive visual loss, loss of vision or a reduction in sensitivity (increase in threshold). Normal limits The normal (monocular) human visual field extends to approximately 60 degrees nasally (toward the nose, or inward) from the vertical meridian in each eye, to 107 degrees temporally (away from the nose, or outwards) from the vertical meridian, and approximately 70 degrees above and 80 below the horizontal meridian. The binocular visual field is the superimposition of the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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