This patient support community is for questions related to juvenile diabetes including celiac disease, depression, diabetic complications, hyperglycemia / diabetic keto-acidosis, hypoglycemia, islet cell transplantation, nutritional issues, parenting a diabetic child, pregnancy, pump therapy, school issues, and teens with diabetes.
I'm also a volunteer, and am a long-time diabetic about your dad's age.
I have learned that it's important for us to be followed by an ophthalmologist who specializes in care of diabetics. Altho' I long thought that an ophthalmogist is specialty enough, I've come to learn that there are specialties within that. When a diabetic's eys are evaluated by a physician who sees hundreds of diabetic eyes and works on hundreds of diabetic eyes, we are benefitting from deep experience.
I have some "internet pals" who have had vitreous surgeries with very good outcomes. Pre-surgery consultation has always included discussions about other conditions and a detailed list of all medications, vitamins, supplements, herbs, etc. that the person takes. The anesthesia choice is an important one, and is made by considering many factors including health conditions and medications, etc.
Read up on the underlying condition and the recommended surgery at reputable sites such as this one:
http://www.nei.nih.gov/neitrials/viewStudyWeb.aspx?id=56
As a person your dad's age, I can say I'd welcome the *informed* involvement of any family member, but can become frustrated when well-meaning, but uninformed folks tell me what to do or to be concerned about. You're clearly in the group of family members who're looking to inform yourself and, unless your dad is too frightened to talk about all this, I imagine he'll be relieved to have an informed conversation with you & to have you participate with him in quizzing & deciphering info from his docs.
Good luck to you both! Your dad is lucky to have you in his court.