They've already got a green light for a sequel

Maybe the title will be "Don't Fart"?

I can see it playing out like this:

In the hospital, the old man regains his sight - the Doctor tells him he banged his visual cortex when he fell into the basement and hit the back of his head.

After his release, his only mission in life is payback!

He tracks Rocky to L.A., where she is living in some cheap rental in the O.C. with her little girl; the old man kidnaps Rocky and her daughter, then pays some homeless lady to take the little girl to a Police station.

The old man has rented an old house with a basement near Joshua Tree (in the desert); he explains to a captive Rocky that he can now see, and now that he's seen how cute she is, he'd chosen not to bother with a turkey baster this time.

Flash forward six years, and Rocky and her son live in that basement, and we have a rip off Room.

But in the desert with a formerly blind man.

Rocky and her new son end up killing the old man and escape; Rocky finds her daughter, and they all three live happily ever after.

Until the ghost of the old man shows up in the (now) teenage daughter's dreams, and we have a ripoff of A Nightmare on Elm Street.

But in the O.C. with the vengeful ghost of a formerly blind man.

Fertile ground for more sequels!