Blindness
Biodegradable stent proves non-inferior to drug-eluting stent
The Orsiro stent, which is a novel stent platform eluting sirolimus from a biodegradable polymer, demonstrated non-inferiority to the Xience Prime everolimus-eluting stent for the primary angiographic endpoint of in-stent ...
Cardiology
1 hour ago |
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Antidepressant reduces stress-induced heart condition
A drug commonly used to treat depression and anxiety may improve a stress-related heart condition in people with stable coronary heart disease, according to researchers at Duke Medicine.
Cardiology
3 hours ago |
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Monoclonal antibody appears effective and safe in asthma Phase IIa trial
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9 hours ago |
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Free distribution of auditory orientation training system for the visually impaired
Researchers from the National Institute of Advanced Industrial Science and Technology (AIST), and the Research Institute of Electrical Communication (RIEC) of Tohoku University have jointly developed an auditory ...
Other
10 hours ago |
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0
Analgesics prescribed more heavily to women than to men, study finds
Regardless of pain, social class or age, a woman is more likely to be prescribed pain-relieving drugs. A study published in Gaceta Sanitaria (Spanish health scientific journal) affirms that this phenomenon is inf ...
Medications
10 hours ago |
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0
New study finds blind people have the potential to use their 'inner bat' to locate objects
New research from the University of Southampton has shown that blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object.
Medical research
May 20, 2013 |
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Diabetes drug tested in Parkinson's disease patients
Parkinson's disease (PD) is a degenerative neurological disorder marked by a progressive loss of motor control. Despite intensive research, there are currently no approved therapies that have been demonstrated to alter the ...
Parkinson's & Movement disorders
May 20, 2013 |
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Pharmaceutical advances offer new options for health outcomes
Research presented at Digestive Disease Week (DDW) explores pharmaceutical advances for treating irritable bowel syndrome with diarrhea (IBS-D) and hepatitis C.
Diseases, Conditions, Syndromes
May 20, 2013 |
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Computational tool translates complex data into simplified 2-dimensional images
In their quest to learn more about the variability of cells between and within tissues, biomedical scientists have devised tools capable of simultaneously measuring dozens of characteristics of individual ...
Medical research
May 19, 2013 |
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Research examines new methods for managing digestive health
Research presented at Digestive Disease Week (DDW) explores new methods for managing digestive health through diet and lifestyle.
Cancer
May 19, 2013 |
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1
Early screenings key to diagnosing glaucoma
New research is emphasizing the importance of regular screenings for glaucoma, a disease that deteriorates the optic nerve over time and is a leading cause of irreversible blindness worldwide. The onset of glaucoma is associated ...
Ophthalmology
May 17, 2013 |
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The artificial pancreas that keeps tabs on sugar
(Medical Xpress)—Development of a sophisticated artificial pancreas holds potential to transform the lives of patients with Type 1 diabetes.
Diabetes
May 16, 2013 |
5 / 5 (1) |
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Tissue damage from metal-on-metal hip implants appears before pain symptoms appear
Metal-on-metal hip implants can cause inflammation of the joint lining (synovitis) long before symptoms appear, and magnetic resonance imaging (MRI) can be used to identify this inflammation, according to ...
Surgery
May 15, 2013 |
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EU court finds Swiss assisted-suicide laws vague (Update)
An elderly Swiss woman who would rather end her life now than decline further in health found sympathy Tuesday from the European Court of Human Rights, which called on the Swiss to clarify their laws on so-called passive ...
Other
May 14, 2013 |
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Lyme disease vaccine shows promise in clinical trial
(Medical Xpress)—The results of a phase 1/2 clinical trial in Europe of an investigational Lyme disease vaccine co-developed by researchers at Stony Brook University, Brookhaven National Laboratory, and at Baxter International ...
Medications
May 13, 2013 |
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Blindness is the condition of lacking visual perception due to physiological or neurological factors. Various scales have been developed to describe the extent of vision loss and define blindness. Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP, an abbreviation for "no light perception." Blindness is frequently used to describe severe visual impairment with residual vision. Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source.
In order to determine which people may need special assistance because of their visual disabilities, various governmental jurisdictions have formulated more complex definitions referred to as legal blindness. In North America and most of Europe, legal blindness is defined as visual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet (6.1 m) from an object to see it—with corrective lenses—with the same degree of clarity as a normally sighted person could from 200 feet (61 m). In many areas, people with average acuity who nonetheless have a visual field of less than 20 degrees (the norm being 180 degrees) are also classified as being legally blind. Approximately ten percent of those deemed legally blind, by any measure, have no vision. The rest have some vision, from light perception alone to relatively good acuity. Low vision is sometimes used to describe visual acuities from 20/70 to 20/200.
By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, low vision is defined as visual acuity of less than 20/60 (6/18), but equal to or better than 20/200 (6/60), or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction. Blindness is defined as visual acuity of less than 20/400 (6/120), or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.
Blind people with undamaged eyes may still register light non-visually for the purpose of circadian entrainment to the 24-hour light/dark cycle. Light signals for this purpose travel through the retinohypothalamic tract and are not affected by optic nerve damage beyond where the retinohypothalamic tract exits.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
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