Genetic defects in Blindness
People with albinism often suffer from visual impairment to the extent that many are legally blind, though few of them actually cannot see. Leber’s congenital amaurosis can cause total blindness or severe sight loss from birth or early childhood.
Recent advances in mapping the human genome have identified other genetic causes of low vision or blindness. One such example is Bardet-Biedl syndrome.A small portion of all cases of blindness are caused by the intake of certain chemicals. A well-known example is methanol  , found in methylated spirits, which are sometimes used by alcoholics as a cheap substitute for regular alcoholic beverages.
Blinding has been used as an act of vengeance and torture in some instances, to deprive a person of a major sense by which they can navigate or interact within the world, act fully independently, and be aware of events surrounding them.
There exist a number of organizations, such as International Agency for the Prevention of Blindness, ORBIS International, and Seva Foundation, who have developed programs aimed at preventing blindness.
On September 10, 2007, in a 6-year study, researchers, led by John Paul SanGiovanni of the National Eye Institute, Maryland found that Lutein and zeaxanthin (nutrients in eggs, spinach and other green vegetables) protect against blindness (macular degeneration), affecting 1.2 million Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD (journal Archives of Ophthalmology). Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas and Brussels sprouts.
A tactile feature on a Canadian banknote.Visually impaired and blind people have devised a number of techniques that allow them to complete daily activities using their remaining senses. These might include the following:
Adaptive computer software that allows people with visual impairments to interact with their computer via audio or screen magnifiers.
Adaptive mobile phones that allows people with visual impairments to interact with their phones via audio or screen magnifiers. These mobile phones uses software called Mobile Speak a screen reader from Code.
Adaptations of banknotes so that the value can be determined by touch. For example:
In some currencies, such as the euro, pound sterling and Australian dollar, the size of a note increases with its value.
Many banknotes from around the world have a tactile feature to indicate denomination in the upper right corner. This tactile feature is a series of raised dots, but it is not standard Braille .
It is also possible to fold notes in different ways to assist recognition.
Labeling and tagging clothing and other personal items
Placing different types of food at different positions on a dinner plate
Marking controls of household appliances
Most people, once they have been visually impaired for long enough, devise their own adaptive strategies in all areas of personal and professional managemen.