Other

Many baby formula plants weren't inspected because of COVID

U.S. regulators have historically inspected baby formula plants at least once a year, but they did not inspect any of the three biggest manufacturers in 2020, according to federal records reviewed by The Associated Press.

Ophthalmology

Drug treatment for cataracts moves a step closer

A revolutionary new treatment for cataracts has shown extremely positive results in laboratory tests, giving hope that the condition, which currently can only be cured with surgery, could soon be treated with drugs.

Ophthalmology

Allowing blind people to see again with a wireless implant

Being able to see without eyes sounds like a miracle, but in the not-too-distant future, a new brain chip could allow the blind and visually impaired to perceive images again. Ph.D. student Adedayo Omisakin worked on wireless ...

Psychology & Psychiatry

Blind people remember language better than sighted people do

Blind people can remember speech better than sighted people, but a person's ability to see makes no difference in how they remember sound effects, found a new study by Johns Hopkins University and the University of California, ...

Neuroscience

Like social media feeds, our brains take a little while to update

Like our social media feeds, our brains are constantly uploading rich, visual stimuli. But instead of seeing the latest image in real time, we actually see earlier versions because our brain's refresh time is about 15 seconds, ...

Neuroscience

Seeing and hearing: How they interplay in the brain

As it is common experience, our senses do not work in complete isolation from the others: sight helps listening (and this is maybe why it is difficult to understand people when they speak with their mask on) but can also ...

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Blindness

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 vision correction—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 6/18 (20/60), but equal to or better than 3/60 (20/400), 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 3/60 (20/400), or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.

It should be noted that 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, so a damaged optic nerve beyond where the retinohypothalamic tract exits it is no hindrance.

This text uses material from Wikipedia, licensed under CC BY-SA