sharp-sightedness vs sharp-sighted

sharp-sightedness is a noun but sharp-sighted is not a noun.

Word	Noun	Adjective	Verb	Adverb
sharp-sightedness	Yes	No	No	No
sharp-sighted	No	Yes	No	No

sharp-sightedness (noun)	sharp-sighted (noun)
lively attentiveness
sharpness of vision; the visual ability to resolve fine detail (usually measured by a Snellen chart)

sharp-sightedness (adjective)	sharp-sighted (adjective)
	keenly perceptive or alert
	having very keen vision