nearsightedness vs ametropia

nearsightedness and ametropia both are nouns.

Word	Noun	Adjective	Verb	Adverb
nearsightedness	Yes	No	No	No
ametropia	Yes	No	No	No

As nouns, ametropia is a hypernym of nearsightedness; that is, ametropia is a word with a broader meaning than nearsightedness:

nearsightedness: (ophthalmology) eyesight abnormality resulting from the eye's faulty refractive ability; distant objects appear blurred
ametropia: (ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia

nearsightedness (noun)	ametropia (noun)
(ophthalmology) eyesight abnormality resulting from the eye's faulty refractive ability; distant objects appear blurred	(ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia