As from the history your dad is a known patient with glaucoma
, but unfortunately he has lost his complete vision in one eye because of advanced stage of glaucoma. Since it has become red now, which probably indicates absolute stage of glaucoma.
The treatment options available are laser
cyclophotocoagulation or cryo photocoagulation to the affected pain for pain relief. Removal of the eye ball is usually not required.
The most important part is treatment for the other eye as he has already lost vision in one eye. Hence I advice you to consult eye doctor or preferably glaucoma specialist for treatment.