APA Dictionary of Psychology

partial or total inability to see, or to see normally, due to partial or complete loss or absence of vision or to visual dysfunction. Visual impairment encompasses the continuum from blindness to low vision. It can result from disease or degenerative disorder (e.g., cataract, glaucoma, diabetic retinopathy, or macular degeneration), injury, or congenital defects (e.g., refractive errors, astigmatism). The degree of visual impairment is assessed in terms of disability in everyday life. Also called vision impairment. See also adventitious visual impairment; congenital visual impairment.