Tove'
I have severe dry eyes and have been diagnosed with Sjogrens syndrome. It mostly affects women, but men can have it too. I use over the counter lubricating drops throughout the day. I also have my puncta (drainage ducts in the eyes) cloesd up to keep as much moisture on them as possible. The final thing is use are called lacriserts and those work well for me. I would get your son to an eye doctor who is familiar with these things I have mentioned and start tying them.