Prolonged pain and discomfort can easily lead to severe Depression and discouragement. When the symptoms go on for months or years then everyday is a struggle, and the future seems bleak and hopeless. All the positive thinking, prayers, chants and other ways meant to change one's perception can be negated by another wave of pain or, in your son's case the vision problems. I know I have had thoughts of suicide more than once, and while I don't know your son, I can sense the discouragement he must be feeling from your posts. The main thing is to not totally give up hope. Even in the darkest times, hope is a tiny glowing light. Try to encourage him with hope all you can.
If you feel emotional issues are at work then perhaps some supplements of St. John's Wort and 5-HTP might help. Try some EFT too, this Emotional Freedom Technique can help, all he needs to do is repeat something like even though my eyes feel pointy and covered with mesh, I still love and respect myself. This is done while tapping certain points on the body. Complete instructions can be downloaded for free at http://www.mercola.com or http://www.emofree.com I can get temporary relief from doing this, EFT can also help your son deal with anger and emotional issues. It might help you control stress that you must be feeling too.
I would suggest he take magnesium supplements, Omega 3 EFAs-fish oil, flax oil, walnuts, raw pumpkin seeds, tuna, salmon are all good sources; plus either St John's Wort or 5-HTP (or both) all of these things can help equalize emotions and aid with reducing depression. Also, makes sure he breathes in fresh air using some yoga breathing techniques and spends some quiet time in the sunlight (although he may need to shade his eyes) let his skin get some early morning or late evening sun. These things will help improve his physical and emotional health and hopefully he will see some improvement with his eyes.