Visual impairment is when a person has sight loss that cannot be corrected using glasses or contact lenses.
There are two main categories of visual impairment:
being partially sighted or sight impaired – where the level of sight loss is moderate
severe sight impairment (blindness) – where the level of sight loss is so severe that activities that rely on eyesight become impossible
How vision is measured
There are two main areas that are looked at when someone’s vision is measured:
visual acuity – which is your central vision and is used to look at objects in detail, such as reading a book or watching television
visual field – which is your ability to see around the edge of your vision while looking straight ahead