Visual impairment (VI) refers to a significant reduction in vision that cannot be corrected with standard glasses, contact lenses, medication, or surgery. This includes conditions such as low vision and blindness, which can impact a person's ability to perform everyday activities. Additionally, color blindness is considered a form of visual impairment, affecting how individuals perceive colors.
| Total blindness | no light perception |
| Severe low vision | visual acuity of 6/120 or worse (seeing an object within 6M , as compared with the normal range at a distance of 120M or above); or, visual field: 20 degrees or less |
| Moderate low vision | vision acuity of 6/60 to better than 6/120 |
| Mild low vision | visual acuity of 6/18 to better than 6/60 |