He also has cataracts. Is there anything holistic that can be done for those?
Cataracts are much easier to prevent than they are to get rid of once formed. There are old eye drops made from the plant dusty miller that were used to dissolve cataracts, but they are caustic so they must be used carefully. A safer choice is to look for shi jue ming, which is an old Chinese remedy for dissolving cataracts when used internally. So it can be added to his food. It will take a while though to work.
Natural vitamin E sources, such as wheat germ oil, are great for helping to prevent most cataracts. If he has glaucoma or diabetes causing the cataracts then these also need to be addressed.