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.

A nephrologist is a medical professional who specializes in diagnosing and treating diseases and disorders that affect the kidneys. Nephrologists are often referred to as kidney specialists. Some nephrologists also do research that helps them learn more about kidney diseases, so they can produce better treatments for their patients.

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.