Did you know that 1.3 billion people worldwide have some form of visual impairment? Blindness and low vision, for example, can be caused by diseases such as glaucoma, or by genetics. These conditions are based on two criteria: the decrease of visual acuity and the decrease of the field of vision. A person is considered blind or to have low vision when both eyes meet one of these criteria:
People with visual acuity below 6/21 or 20/70 are considered to have low vision. That means that they can only see at a distance of 6 metres (20 feet) compared to someone with perfect vision who sees at a distance of 21 metres (70 feet). A person is also considered to have low vision when their field of vision is less than 60 degrees. Unfortunately, the vision of these people cannot be corrected or improved, even with glasses, contact lenses or surgery. It is difficult for them to practise their daily activities, such as reading, writing or moving around without help. Driving a car is also not possible in their case.
A person is considered to be blind if their visual acuity is of 20/200 or 6/60 or less. People with a visual sharpness of 20/200, can only read the first line of the eye chart, the big "E". Blindness can also be characterized by a vision field of less than 20 degrees, which represents tunnel vision. There is a misconception that the visually impaired live in the dark, as if their eyes were closed. However, most of them can perceive light and even certain movements. If no form of light or movement can be perceived, then we speak of total blindness.
Several services are available to people with low vision or blindness to help them function in their daily activities. For reading, a screen can be provided to them to magnify the characters of a newspaper, for example. White canes or electronic obstacle sensors can also help them get around. Some people also use guide dogs to help them get around. For students and workers, they can use systems to help with their work or studies, such as a screen that magnifies the characters to help them read, or even a Braille printer.
Despite being visually impaired, most people with low vision or blindness can cope in their everyday lives and read, write and move around. Some organizations offer services for people with visual impairments and can provide them with support systems, or help them develop skills to be as independent as possible. Would you like to learn more about low vision and blindness? Talk to your optometrist during your next visit.