Cave snake?

So, this is going to seem incredibly naive of me, I just know it, but I wanted to see if this could possibly be true.

Yesterday I took my kids to the Caverns of Sonora in west Texas for a cave tour. (The cavern is absolutely gorgeous btw, and although expensive I would recommend it if you're ever in the area.) The tour level goes down to about 155 feet, but the explored caverns go to about 280. Our tour guide stated that there are snakes that live in the deeper levels of the cave, that rarely come up to the tour levels, and that are apparently related to cottonmouths. He said that they are eyeless and colorless, to the point of transparency, and that he has seen these snakes himself.

I know that many animals live in caves and adapt in that way; salamanders, scorpions, crayfish, fish, etc. I've never heard of this happening to reptiles or mammals, however.

Anyone else EVER heard of this happening, or of a species of snake that could possibly match this description?

There are cave snakes! now I don't know if what your guide told you is accurate or not but there are species of cave dwelling snakes . This is from -Ecology Asia..
"The Cave Dwelling Snake or Cave Racer inhabits limestone caves, occasionally venturing to the cave entrance. It is considered a specialised subspecies of the more widespread Elaphe taeniura.

The anterior scales are yellowish-brown or beige, and the posterior scales black, with a thick, white or yellow vertebral stripe. The head is slender and bears a thick, black eye-mask. The top of the head is bluish. It preys mainly on bats."
Randy

Yup, Cave racers are beautiful rat snakes, close relatives of Blue Beauties and Taiwanese Beauties.

are the eyes on cave snakes underdeveloped like those of many other cave dwelling species?