Definition of Blindness and vision loss:

Blindness is a lack of vision. It may also refer to a loss of vision that cannot be corrected with glasses or contact lenses.

• Partial blindness means you have very limited vision.
• Complete blindness means you cannot see anything and do not see light. (Most people who use the term "blindness" mean complete blindness.)

People with vision worse than 20/200 are considered legally blind in most states in the United States.

Vision loss refers to the partial or complete loss of vision. This vision loss may happen suddenly or over a period of time.

Some types of vision loss never lead to complete blindness.

Common Causes:

Blindness has many causes. In the United States, the leading causes are:

• Accidents or injuries to the surface of the eye (such as chemical burns or sports injuries)
• Diabetes
• Glaucoma
• Macular degeneration

The type of partial vision loss may differ, depending on the cause:

• With cataracts, vision may be cloudy or fuzzy, and there may be problems seeing shapes
• With diabetes, vision may be blurred, there may be shadows or missing areas of vision, and difficulty seeing at night
• With glaucoma, there may be tunnel vision and blurry vision
• With macular degeneration, the side vision is normal but the central vision is slowly lost

Other causes include:

• Blocked blood vessels
• Complications of premature birth (retrolental fibroplasia)
• Complications of eye surgery
• Lazy eye
• Optic neuritis
• Stroke
• Retinitis pigmentosa
• Tumors such as retinoblastoma and optic glioma