Blindness

New-age prosthetic technique enables blind mice to see

(Medical Xpress) -- A recent TEDMED talk has scientists interested in a presenter’s novel techniques to help the blind. A device with two parts, encoder and transducer, can do the job. Sheila Nirenberg, a neuroscientist and professor at Weill Medical ...

Dec 23, 2011
popularity 5 / 5 (15) | comments 9 | with audio podcast report

Dr. Oz's questionable wizardry

Miracles are pretty rare events. Except on television's Dr. Oz Show, where they appear with astonishing frequency. Oz of course doesn't claim to raise the dead or part the Red Sea, but he does raise people's ...

Dec 31, 2013
popularity 4.6 / 5 (11) | comments 0

Algae may be the solution to blindness

(PhysOrg.com) -- The song about three blind mice may just be a song of the past according to new research presented by neuroscientist Alan Horsager from the Institute of Genetic Medicine at the University of Southern California ...

Apr 15, 2011
popularity 4.7 / 5 (9) | comments 1 | with audio podcast report

Loneliness is a major health risk for older adults

Feeling extreme loneliness can increase an older person's chances of premature death by 14 percent, according to research by John Cacioppo, professor of psychology at the University of Chicago.

Feb 16, 2014
popularity 4.3 / 5 (8) | comments 0

A short stay in darkness may heal hearing woes

Call it the Ray Charles Effect: a young child who is blind develops a keen ability to hear things that others cannot. Researchers have long known that very young brains are malleable enough to re-wire some ...

Feb 05, 2014
popularity 5 / 5 (6) | comments 1 | with audio podcast

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 licensed under CC BY-SA

Latest Spotlight News

Turning off depression in the brain

Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain's reward circuit and experimentally reversed it – but there's ...

New MRSA superbug emerges in Brazil

An international research team led by Cesar A. Arias, M.D., Ph.D., at The University of Texas Health Science Center at Houston (UTHealth) has identified a new superbug that caused a bloodstream infection ...

Classifying cognitive styles across disciplines

Educators have tried to boost learning by focusing on differences in learning styles. Management consultants tout the impact that different decision-making styles have on productivity. Various fields have ...

Bionic ankle 'emulates nature'

These days, Hugh Herr, an associate professor of media arts and sciences at MIT, gets about 100 emails daily from people across the world interested in his bionic limbs.