Vision insurance and medical insurance gets confusing. Both deal with the eyes. If you have a medical eye disease, you probably need a thorough dilated eye exam. This should be covered by your "health" insurance.
Small study reports that diabetic macular edema is better treated with intraocular injections of anti-VEGF medications. These small studies aren't large enough to change practice habits, but do have some merit.
Vision requirements in most states require good vision in only one eye! Patients with diabetic retinopathy and macular degeneration usually do not lose their driver's license due to vision requirements.