mydriasis vs reflex action

mydriasis and reflex action both are nouns.

Word	Noun	Adjective	Verb	Adverb
mydriasis	Yes	No	No	No
reflex action	Yes	No	No	No

As nouns, reflex action is a hypernym of mydriasis; that is, reflex action is a word with a broader meaning than mydriasis:

mydriasis: reflex pupillary dilation as a muscle pulls the iris outward; occurs in response to a decrease in light or certain drugs
reflex action: an automatic instinctive unlearned reaction to a stimulus

mydriasis (noun)	reflex action (noun)
reflex pupillary dilation as a muscle pulls the iris outward; occurs in response to a decrease in light or certain drugs	an automatic instinctive unlearned reaction to a stimulus