A visual impairment refers to both eyes having significant loss of vision that cannot be fixed with glasses. There are two categories for visual impairments, low vision and total blindness.
In order to be diagnosed with low vision, one must have sight with a visual acuity of 20/70 or less, that cannot be corrected with glasses. With a visual acuity of 20/200 or less, an individual is considered to be legally blind. Those with legal blindness usually are able to distinguish light and may be able to see forms.
Total blindness refers to possibly having some light perception, but little else.