presbyopia vs longsightedness

presbyopia and longsightedness both are nouns.

Word	Noun	Adjective	Verb	Adverb
presbyopia	Yes	No	No	No
longsightedness	Yes	No	No	No

As nouns, longsightedness is a hypernym of presbyopia; that is, longsightedness is a word with a broader meaning than presbyopia:

presbyopia: a reduced ability to focus on near objects caused by loss of elasticity of the crystalline lens after age 45
longsightedness: abnormal condition in which vision for distant objects is better than for near objects

Other hypernyms of presbyopia include farsightedness, hypermetropia, hypermetropy, hyperopia.

presbyopia (noun)	longsightedness (noun)
a reduced ability to focus on near objects caused by loss of elasticity of the crystalline lens after age 45	abnormal condition in which vision for distant objects is better than for near objects