As far as i know it's ungrammatical to use the verb form seeing when perception is involved - do you mean specifically the gerund seeing, or any use of to see?
Either way, it sounds wrong to this us.
Idiomatically, what do you see?
Can also be taken to mean what are you capable of seeing?
(as a human being, what do you see?) the answer could be the wavelengths of light observable by the.