What is Blindness?

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What is Blindness?

Blindness is a condition in which there is a full or partial lack of sight, as a result of a congenital defect or hereditary disease, or due to injury, defect or disease affecting the eyes, the optic nerve or the brain. Systemic diseases affecting the body, such as diabetes and high blood pressure can harm the eye and the visual perception and can also cause blindness. It is important to point out that the condition of blindness cannot be corrected by the wearing of glasses or contact lenses.

It should be noted that it is a mistake to use the term ‘blindness’ to describe conditions that are unrelated to visual field or acuity, such as in the term ‘color blindness’. The condition of ‘color blindness’ should actually be called ‘Color Vision Deficiency’.

It is possible to distinguish between the condition of total blindness, indicated by the complete lack of light perception, and the condition of partial sight, in which the ability to perform everyday tasks is severely impaired. The State of Israel, together with the majority of developed countries, defines ‘blindness’ according to the definition of UNESCO (United Nations Educational, Scientific and Cultural Organization).

Two main parameters regarding visual perception are taken into consideration when defining blindness: Distance Visual Acuity and Field of Vision.
Distance Visual Acuity - the ability to see detail, such as recognition of characters or letters in different sizes. Normal vision is defined by the numbers 6/6, while a blind person is defined as having 3/60 vision or worse.
Field of Vision – the central and peripheral fields of view. A normal field of vision encompasses 180° (a semi-circle). A person is defined as blind when his field of vision encompasses less than 20°.
While visual impairment is not defined as blindness, it refers to a condition of impaired visual ability which interferes with the performance of everyday tasks. Some visually

impaired persons are able to perform various tasks that blind persons cannot perform independently, while other visually impaired persons require the assistance of special equipment in order to perform those same tasks.

According to the World Health Organization, there are approximately 40-45 million blind persons in the world (2004), and approximately 160 million visually impaired persons. According to the Israeli Ministry of Social Affairs and Social Services, as of 2010 approximately 26,000 legally blind and visually impaired persons live in Israel, and approximately 2,000 cases of blindness are added every year. The percentage of totally blind persons within the whole blind community is decreasing relative to the age of the individuals. Every year some 5,000 eye injuries occur in Israel due to accidents in the workplace, 2,500 occur in schools and about 600 during sports or other leisure activities. However, over 90% of these injuries could be prevented through observation of safety rules and the use of protective equipment.

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