A gastroenterologist is a healthcare professional who has been educated and trained to treat patients who are experiencing health problems or have diseases that affect the gastrointestinal tract and liver. They also diagnose and treat diseases that affect the esophagus, stomach, small intestine, colon, rectum, pancreas, gallbladder, bile ducts, and liver.

An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.

Optometry is a medical profession that deals with the eyes and eye health. Optometrists can look at patients’ eyes to address abnormalities or irregularities as well as diagnose diseases of the eye. These doctors may also refer patients to surgeons who can correct eye problems. While optometrists do also focus on helping people find corrective lenses that can improve their vision, their focus extends far beyond glasses and contacts to include overall eye health, including management of eye diseases.