A fundoscopy is a type of eye test that examines the back of the eye. As this test allows a doctor to view the structures in the eye, it can help them diagnose conditions that impact the retina, such as diabetic retinopathy.

Diabetic retinopathy (DR) is an eye condition that may occur as a potential complication of diabetes. It occurs when high blood sugar levels damage the small blood vessels present in the retina, which is the delicate layer of cells lining the inside of the eye. This layer senses light and sends signals to the brain that enables vision.

DR is the leading cause of blindness in adults and the most common cause of vision loss for people with diabetes. As such, it is important to have regular eye exams to help catch the condition early and prevent complications. One eye test a person may have is a fundoscopy. This test examines the back of the eye, including the retina.

In this article, we will discuss what a fundoscopy is and how it can help with diagnosing DR.

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Fundoscopy, also known as ophthalmoscopy, describes a type of eye exam. This test uses either a hand-held ophthalmoscope — direct fundoscopy — or a magnifying lens and a head-mounted light — indirect fundoscopy — to check the fundus of the eye. The fundus refers to the back of the inside of the eye and includes the retina. An eye doctor may also use fundus photography to take a picture of the back of the eyes.

As such, an eye doctor can use fundoscopy to check the retina for eye problems, such as DR. This can allow them to detect the condition or monitor its progress.

While performing a fundoscopy, the doctor will view the structures of the eye and look for signs of DR, which may include:

  • Microaneurysms: Appearing as tiny red dots in the retina, these are usually the earliest visible signs of DR. They refer to tiny bulges in the blood vessels in the back of the retina, which may leak small amounts of blood.
  • Cotton wool spots: These refer to white, fluffy patches that appear on the surface of the retina. These irregular patches are a common sign of DR and occur due to a reduction in blood flow and oxygen, resulting in the retinal nerve fiber layer swelling.
  • Hemorrhages: This describes when bleeding occurs in the retina. A doctor may check for different types of hemorrhages, which may include Roth spots, dot, flame, or vitreous hemorrhages.
  • Hard exudates: Typically occurring with microaneurysms, these refer to white or yellow deposits surrounding the leaking vessel.

Click here to learn more about diabetic eye screening.

As fundoscopy allows an eye doctor to view the structure of the retina, it is an important screening tool for DR. As such, health experts recommend that individuals with diabetes attend regular exams to check their eye health. Not only can early detection and treatment stop damage and prevent blindness, but fundoscopy can also allow the doctor to monitor the condition.

However, a 2022 study suggests that fundoscopic exams with a hand-held ophthalmoscope are a suboptimal option to screen for DR in primary care settings. It indicates that more research is necessary to identify more effective screening strategies.

This test uses eye drops to dilate, or widen, the pupil, which provides an optometrist or ophthalmologist a better view of the eye’s fundus to help them detect potential problems.

After dilating the pupil, the examiner will then use the fundoscope to view the inside of the eye, which allows them to assess the retina, blood vessels, and other features inside the eye.

A person will not need to prepare anything before a fundoscopic exam. After applying the eye drops, it may take 20–30 minutes for a person’s pupils to dilate fully. The doctor will then darken the room and use the fundoscope to examine the eye. They may pivot the fundoscope or ask the person to look in different directions to view all angles of the fundus.

Typically, a doctor will use a comprehensive eye exam to diagnose DR. In addition to fundoscopy, other tests may include:

  • visual acuity measurements to test central vision
  • refraction tests to determine if a person requires a new eyeglass prescription
  • measuring pressure within the eye
  • using a slit-lamp biomicroscope to examine structures in the eye

While a fundoscopic exam can help detect and monitor DR, problems, such as cataracts, may make it difficult to clearly see the fundus of the eye. A doctor may also wish to see different structures in the eye. Other diagnostic investigations for DR may include:

  • Fluorescein angiogram: This test also uses a special camera to view structures at the back of the eye. However, this test uses a yellow dye, called fluorescein, which a doctor injects intravenously. This helps the doctor take a better look at the eye’s blood vessels and identify any damage or abnormalities.
  • Optical coherence tomography: This test uses light waves to create a cross-section image of the retina. This enables an eye doctor to map and measure the thickness of different retinal layers, helping them diagnose eye conditions.
  • Ophthalmologic ultrasound: As the eye contains fluid, ultrasonography can be useful to visualize the structures in the eye. Similar to other types of ultrasound, it uses sound waves to create an image.

Diabetic retinopathy is a potential complication of diabetes and the leading cause of blindness. Early detection is important to help manage the condition and prevent vision loss.

To help detect diabetic retinopathy, health experts recommend regular eye tests, which will include a fundoscopic exam. This test involves a doctor looking at the back of the eye. They will look for signs of DR, which can include microaneurysms, exudates, and white patches in the retina that suggest blood vessel damage.