Blindness is strictly defined as the state of being totally sightless in both eyes. A completely blind individual is unable to see at all. The word blindness, however, is commonly used as a relative term to signify visual impairment, or low vision.

Reference: Medical Author: Andrew A. Dahl, MD, FACS / Medical Author: Andrew A. Dahl, MD, FACS  Medical Editor: William C. Shiel Jr., MD, FACP, FACR https://www.medicinenet.com/blindness/article.htm , consulted on june 30th,2019