How Doctors Diagnose Diabetic Macular Edema

Diabetic Macular Edema (DME) is diagnosed by a doctor, often an eye specialist (eg, ophthalmologist) who treats diabetic retinopathy. The doctor carefully reviews the patient's medical history because DME is a complication of diabetes.

Types of information that help diagnose the severity of DME include:

  • How long has the patient had diabetes
  • Type of diabetes
  • Blood pressure (eg, hypertensive, high blood pressure)
  • Does the patient retain fluid
  • Lab test results (eg, fats and proteins in the blood)


Eye examination
The doctor examines the areas around each eye, eye alignment and movement. Using a hand-held light source called an ophthalmoscope, he inspects the inside of each eye. By moving the ophthalmoscope toward the eye and adjusting its angle, the doctor can examine the macula and retina.

Vision test
Vision is tested using a standardized chart viewed from a distance by the patient.

Slit lamp
The slit lamp is a microscope equipped with a high-intensity light. It enables the doctor to view the macula and retina three-dimensionally. Often, before the test, fluroescien—a temporary eye stain—is added to each eye to assess the cornea. Next, the patient's pupils (black center of each eye) are dilated using drops that cause the size of each pupil to widen—like opening a window to see more of what's inside.

When the pupils are sufficiently dilated (about 15 minutes), the patient is seated behind the slip lamp and rests their forehead and chin in the instrument's support. The doctor sits opposite the patient, and holds a small lens close to one eye at a time to examine the inside. Photographs of the interior of each eye are taken.


Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Complications of diabetes mellitus. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders;2011.

Robinett DA, Kahn JH. The physical examination of the eye. Emerg Med Clin North Am. 2008:26(1).