Visual impairment or vision impairment is vision loss that constitutes a significant limitation of visual capability resulting from isease, trauma, or a congenital or degenerative condition that cannot be corrected by conventional means, including refractive correction, medication, or surgery. This functional loss of vision is typically defined to manifest with 1) best corrected visual acuity of less than 20/60, or significant central field defect, 2) significant peripheral field defect including homonymous or heteronymous bilateral visual field defect or generalized contraction or constriction of field, or 3) reduced peak contrast sensitivity either of the above conditions.