Problem in the DR is you don't have to indicate what degree you have when you call yourself a Dr. In most states in the US, if you indicate that you are a doctor and are not a medical doctor (MD) or an osteopath (DO), you must further indicate that you are an optometrist (OD), chiropractor(DC), podiatrist (DPM), psychologist (PhD or PsyD), etc.
Although an opthalmologist is better trained in treatment of ocular disease, most find it beneath themselves to do vision exams and keep asking "is that better or worse". I have found optometrists give a better vision exam. That is why most opthalmologists in the US are associated with optometrists and do different parts of the patient's evaluation.