First of all, here is a great link that talks about KCS. Please read it to help increase your understanding of the disease and what our goals are.
So, in summary KCS is the decreased tear production of that eye. Our goal is to increase that production, but this is not always possible. In your case, the first thing that I would absolutely do is to use the Veterinary approved cyclosporine topical product called optimmune. The Restasis is the human medication for dry eye with optimmune in it. The difference between the products is that the Restasis has a 0.05% concentration of the cyclosporine where the optimmune has a 0.2% concentration.
So the veterinary product is much stronger and has a better chance of stimulating the tear glands. If it is going to stimulate them. I always start my KCS cases on the veterinary product.
Sometimes other topical medications are needed to help break up the mucous in the eye. Here is copy from the above link.
Mucomyst® Eye Drops are made from a respiratory product used to dissolve thick mucus. In an eye formula, Mucomyst (active ingredient is Acetylcysteine) helps remove the thick eye discharge that accompanies dry eye.
Severin's Solution is a mixture of Mucomyst, pilocarpine, artificial tears, and antibiotic that can be made up and prescribed. The recipe originated in an article published by a veterinary ophthalmologist named Dr. Severin in 1996. Many animal hospitals mix up their own conglomerations based on this recipe. In most cases, cyclosporine has made these mixtures obsolete.
Both of these can be used if the optimmune doesn't work.
So again, ask your vet to get you the vet product for dry eye and make sure you use it twice a day for a couple weeks and then recheck his tear production to see if the glands have responded. They may or may not depending on how much functional gland is left.