visual impairment vs visual defect

visual impairment and visual defect both are nouns.

Word	Noun	Adjective	Verb	Adverb
visual impairment	Yes	No	No	No
visual defect	Yes	No	No	No

As nouns, visual impairment and visual defect are synonyms defined as:

Other synonyms of visual impairment include vision defect, visual disorder.

visual impairment (noun)	visual defect (noun)
impairment of the sense of sight	impairment of the sense of sight