I Take Zioptan To Control Glaucoma. I Used To Take

I take Zioptan to control Glaucoma. I used to take Lumigan which kept pressure in check but was causing eye infections which is why my physician switched to Zioptan. (it is preservative free) My insurance company is giving me a hard time on covering Zioptan and has recommended Latanoprost instead. is it preservative free and a good alternative to Zioptan?