aphakia vs visual defect

aphakia and visual defect both are nouns.

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

As nouns, visual defect is a hypernym of aphakia; that is, visual defect is a word with a broader meaning than aphakia:

aphakia: absence of the natural lens of the eye (usually resulting from the removal of cataracts)
visual defect: impairment of the sense of sight

Other hypernyms of aphakia include vision defect, visual disorder, visual impairment.

aphakia (noun)	visual defect (noun)
absence of the natural lens of the eye (usually resulting from the removal of cataracts)	impairment of the sense of sight