CD/DVD Lens Cleaners-How Safe are they?

I recently got my CD ROM serviced because the lens was Spoilt. I agree my CD ROM is over 4 years old, but I do know of CD ROMs that last longer.
I used to regularly clean my CD ROM with a disc cleaning CD (The one with a single tiny brush – no liquid) – as per the instructions on the CD lens cleaner pack. I would like to know whether such cleaning is required at all. If so, what are the safe methods. Also for DVD players. Thanks in advance