Ed
I'm quite older than your son and have dry eye for many year. It's a dreadful affliction and sorry to say there's no cure; only treatment. I've been to 7 or 8 opthamologists re; the condition. It's depressing. I would recommend a Dr. Brian McNeary in Woodside, NYC. He's about the best. He has no cure, but at least his examination and treatment is the best. Good luck!