In "Lord of the Flies", what is the connection between Ralph, the conch, and the glasses?

I think the main connection is about the idea of democracy and fairness they represent.

Ralph, as chief, represents an idea of democracy and fairness. It's significant, I think, that in the first chapter, when Ralph is elected chief, it is a democratic election and the conch, as a symbol of togetherness, influences the boys' vote: they vote for Ralph because...

...most obscurely, yet most powerfully, there was the conch. The being that had blown that, had sat waiting for them on the platform with the delicate thing balanced on his knees, was set apart.
“Him with the shell.”
“Ralph! Ralph!”
“Let him be chief with the trumpet-thing.”

And then, in the second chapter, it's the conch that becomes the symbol of who can speak, of everyone listening to a single speaker. The conch initially summoned all the boys together: and it now represents keeping them together, a sign of "order, authority, dialogue, democracy":

“Conch?”
"That’s what this shell’s called. I’ll give the conch to the next person to speak. He can hold it when he’s speaking.”

Ralph as chief is chiefly bothered about the fire. It's important, he realises, to have the fire as a signal so that they might be rescued. And this fire needs Piggy's glasses to be lit. The glasses, then are literally and metaphorically associated with clear-sightedness - like Ralph's insistence on the fire.

So you see the link. Ralph, the conch, and the glasses are all tied into Ralph's ideas as chief - the opposite to Jack, hunting, and sharpened sticks!