Visual impairment or loss of vision is defined as blindness. Total blindness refers to that condition when a person is completely unable to perceive light. This person cannot tell light from dark or has no light perception. However even people with light perception can be technically blind. Such people to a certain extent can distinguish between light and dark and can generally perceive the direction of the light.
Many governmental jurisdictions have formulated rather complex definitions to determine what is termed as ‘legal blindness’. Generally when the vision or visual acuity is less than 6/60 – that is if a person is able to identify an object only from a distance of 6.1 meters with a vision correction as clearly as a person with normal vision can see the object at 600 meters – a person is said to be legally blind.
However as per others a person is considered legally blind if he or she has a visual field that is less than about 20 degrees, the normal being 180 degrees
Causes of Blindness
Malnutrition is considered to be the leading cause of blindness.
Glaucoma is another factor, which triggers blindness, and in many cases AMD or Age related Macular degeneration could cause blindness. Cataract, Trachoma and Uvieits may also cause blindness.
Aging is yet another cause for blindness. The instances of blindness are more in developing countries when compared to developed countries. Blindness has also been linked to poverty. This could be due to the fact that methods to treat the possible causes could be expensive and hence due to poverty they are often left untreated. Cataract, which is the cause of blindness in almost 50% of the cases, is not treated in many poverty-stricken areas in the developing countries perhaps due to the affordability factor. This is an easily treatable condition and when not treated it leads to permanent visual impairment.
Vision loss in one eye is termed as monocular vision. An injury, to the eye is the leading cause of monocular vision among the people who are 30 years of age or less. Cataract and injuries cause blindness as they affect the eye. However there are certain abnormalities like optic nerve hyperplasia, which affect the bundle of nerves that are responsible for sending signals from the eye to the brain and back again, which can also lead to severe vision impairment.
Occipital lobe in brain, when damaged, can also lead to blindness even if the optic nerves and the eyes are not damaged. Albinism could lead to blindness. Genetic causes include the Bardet-Beidl syndrome. Inadvertent consumption of chemicals like methanol that is present in methylated spirits also causes blindness. This happens when cheap substitutes alcoholic beverages are consumed.
Treatment for Blindness
If the blindness is caused due to cataract or glaucoma then effective treatment of the malaise can help one to confront it. Blind people can carry on daily activities by using a number of adaptive techniques. Technological advancements made in this area to aid the blind people include computers, mobile phones that have such adaptive features, which enable a blind person to use them.
Currency notes, which have tactile features that help one to identify the denominations, are also helpful in this regard. This feature is present in the upper right hand corner of the bank note. In many countries the size of the currency notes increase with the value. Other adaptive features include helping the visually impaired by:
Tagging or labelling the personal items that they use including clothes.
Placing food items at a particular position on the table or their plates.
Walking techniques could include the use of cane that is extendable and swung around to pave their way around.
Some blind people also use guide dogs. These dogs act as pilots and are trained to help navigate the visually impaired person. There are some organizations or people who professionally train the blind people walk independently. They are called orientation or mobility specialists.
Magnification devices can be used to enlarge the size of the print. Audio books and Braille is a technique that helps the blind to read. While using the computers – there are style sheets designed to increase the size of the font and images through controls. Many modern web browsers cater to the needs of the blind.
To sum up blindness often is a disease, which cannot be cured. However with technological advancements there have been many aids which help the blind people to lead a normal life.
