Bogey had tear stains  years ago and I did 3 things that helped him.  
 
1.  I grew out the hair around his eyes.  
2.  Changed his food to Royal Canine Yorkshire Terrier brand kibble
3. Bought this and it was amazing!  
Eye Envy Pet Dog Starter Kit Tear Stain Remover Cleaner | eBay 
*I've since changed food but for a different reason.  But still no stain.  I believe it's because I grew the hair out.