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November 13 is the International Day of the Blind. This day marks the birthday of French Valentin Hauy (1745-1822). He was the first person to teach blind children, who in 1784 founded the world’s first boarding school for the blind in Paris.

This day is perfect for voicing the social and psychological challenges of visually impaired people.

As of 2012 there were 285 million visually impaired people in the world, of which 246 million had low vision and 39 million were blind. The majority of people with poor vision are in the developing world and are over the age of 50 years.

Blindness is defined by the World Health Organization as vision in a person's best eye of less than 20/500 or a visual field of less than 10 degrees. This definition was set in 1972, and there is ongoing discussion as to whether it should be altered somewhat.

Blind people with undamaged eyes may still register light non-visually for the purpose of circadian entrainment to the 24-hour light/dark cycle. Light signals for this purpose travel through the retinohypothalamic tract and are not affected by optic nerve damage beyond where the retinohypothalamic tract exits.