Blindness

Blindness is substantial or complete loss of sight, ranging from limited visual function to no light perception. It can be present from birth or develop later, and may result from many causes.

Visual acuity: Visual acuity is the sharpness with which fine details can be distinguished, commonly measured with an eye chart. Reduced acuity is one route to functional blindness, even when some sight remains.
Retina: The retina is the light-sensitive neural tissue lining the back of the eye. Damage to its photoreceptors or supporting cells can prevent light from becoming useful visual signals.
Orientation and mobility: Orientation and mobility is training in spatial awareness and safe, independent travel for people with vision loss. It develops strategies for navigating environments without relying on sight.
Retinitis pigmentosa: Retinitis pigmentosa is a group of inherited disorders that progressively damage retinal photoreceptors. It illustrates how genetic retinal disease can gradually cause severe sight loss.
Braille literacy: Braille literacy is the ability to read and write using the tactile Braille system. Literacy access affects education and independent communication for people who are blind.
Visual field: The visual field is the area visible while the eyes focus on a fixed point. Severe field loss can meet blindness criteria despite relatively sharp central vision.
Optic nerve: The optic nerve carries visual information from the retina to the brain. Injury can interrupt signals even when the eye detects light normally.
White cane: A white cane is a mobility aid used by people with vision loss to detect obstacles and signal visual disability. It provides tactile information about the path and nearby hazards.
Age-related macular degeneration: Age-related macular degeneration is a disease that damages the macula, the central part of the retina, in older adults. Its central vision loss can become severe while peripheral vision remains.
Inclusive education: Inclusive education teaches students with disabilities alongside peers while providing appropriate support and accommodations. Accessible materials and teaching practices shape educational opportunities for blind students.

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