UTR, isn't the call of "visual" made to indicate you can make a visual approach, therefore if you are "visual on top" then you are not visual at all (unable to navigate with reference to the ground or water) and should say nothing.
AIP ENR 11.1.6 (b) says:
Identified - report assigned level, flight conditions, if appropriate, and receipt of ATIS (code).
so, no, you shouldn't say 'nothing'
UTR