Is Latisse Safe to Use While on Restasis?

This is a good question. Restasis is cyclosporin A and is used as a drop twice a day for dry eye conditions. It is actually cyclosporine which has an anti-inflammatory action. Specifically it inhibits T cells which are a type of inflammatory cell and thought to be responsible for the inflammatory component of dry eye. Latisse or Lumigan are a different type of medication. They are protoglandin like (prostamide) medications which reduce intraocular pressure and on the skin stimulate the growth of lashes.
Fortunately, the interaction of these two medications should not occur in that the Latisse is to be applied to the skin of the lashes and the Restasis is placed into the eye. Further, they are probably frequently used together in that it is the same demographic who would use both. Women, especially middle aged women are the ones who both suffer from dry eye the most and also are the most interested in Latisse for their lashes.
Since both medications are made by Allergan it would seem that the manufacturer would be aware of any untoward interactions between these two medications, and this has not to my knowledge been reported. It is certainly a good question and always a good policy to be aware of possible drug interactions.

Latisse and Restasis together: no problem.  Latisse is used on the eyelids at the base of the lashes to make them grow longer.  Restasis goes on the eyeballs themselves to treat dry eye. 

I don't see any reason why the two should not be used together. The one thing to remember, though, is that Restasis is being used for dryness of the eye. Both dryness and Restasis can cause stinging and burning. It so happens that Latisse can too, so while you won't be hurting yourself, you might have some trouble figuring out which of the three is the culprit if stinging begins.