Lens pen...Specifically the Lenspen micropro
http://www.lenspen.com/?cPath=1&products_id=MCP-1&tpid=146
But..I have used with GREAT success....
Zeiss lens cleaner solution...should be able to pick up a bottle wherever they carry Zeiss optics...
I got mine at my favorite Gun Shop when I bought a New Zeiss Scope for one of my rifles.
Anyway....get 2-5 new Q-Tips..and spray the solution on one end of a Q-Tip...(Do NOT use that Q-tip to clean the lens..it will be too wet!!!)
Take another Q-tip and touch it to the wet q-tip...this will SLIGHTLY dampen the new Q-tip with solution...
Now Lightly, and carefully use that end to clean the lens. 2-3 strokes.
Now take a New dry Q-tip and go in 2-3 strokes...
LASTLY use a can of compressed air...and lightly blow off the lens...(LIGHTLY>>>NOT FULL PRESSURE)
Your lens should now be clean as a Whistle....
Be gentle in there..that lens is only glued in place..and NEVER use Alcohol!!!!
It will dissolve the glue!!!
Larry