There are many, many causes of legal blindness. It can be the result of a disease or injury, and it can happen at any time, including later years or in childhood. It's a limiting disability, but one with which many people function perfectly.
The lieutenant governor lost his vision because of a childhood infection as an infant. It left him blind in his left eye and with severely limited vision in his right. That limited sight has qualified him as legally blind.
Two years ago, Paterson described his vision in our Eyewitness News "Up Close" program.
"I have optic atrophy, which is the scarring of the optic nerve," he said. "And it has happened to a lot of babies that were in incubators that were too hot, and it burned away their scar tissue."
The optic nerve plays a major part in vision. It is the highway that connects the eye and the brain, where the images are processed.
Impaired vision that meets a specific level of loss is defined as legal blindness. It can be based on acuity or on tunnel vision.
Acuity means a person sees through a cloudy lens. A vision of 20/200 defines legal blindness. That number means that a figure at 200 feet can't be seen well until the patient is 20 feet away.
The other type of loss is the tunnel vision, which means there is no clear peripheral vision.
With both, there is a lot of variation.
The degree of Paterson's vision loss is not clear, but he has been described as surprising one prominent opponent in a basketball game. The opponent was former Governor Mario Cuomo, who told the New York Times, "Just want I wanted, a blind guy to guard me. The second time down the court, he stole the ball."
Advocates of people with low or no vision are welcoming this new attention to the disability.
"This will bring more attention to low vision problems, and will make it more relevant for the average person, there will be more curiosity about services," said Dominique Auguste, of the Jewish Guild for the Blind.
Advocates emphasizes that legal blindness simply means people needs some tools to help them with some functions, but otherwise can perform any job from entry level positions to the head of a state. Paterson told us two years ago that the only thing he can't do is drive a car.
