Capitalizing the first word after a comma doesn’t really make that the start of a new sentence. *shakes head*
Change the comma after world to a period… or better yet, combine the second sentence with the first by adding a conjunction.
Add a comma after hunting.
Change the comma after them to a period.
Change it’s to they’re.
It has been years since the alien invasion changed the world and those who remained fled to the mountains. You accidentally broke your glasses while hunting, and you’re very nearsighted without them. Someone finds you and offers help. You’re pretty sure they’re human.
What I like about this example is the (probably unintended) ambiguity: Maybe the POV character is human, or maybe it’s the alien invaders who are. The latter would make an interesting story.