Singular visual aid? (7,4)

I believe the answer is:

contact lens

(Other definitions for contact lens that I've seen before include "you're supposed to see through it" , "Eyesight corrector" , "Sight corrector" , "Aid to vision" , "Visual aid" .)

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.