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What is a dilated eye exam and when do you need one?

Posted on October 26th, 2018

Has your doctor asked you to undergo a dilated eye exam? Or, have you heard a friend talking about their experience with one?

Let’s take a closer look at the specifics of this exam, and how it’s different from the more common Optomap exam you might be familiar with.

What’s the difference between them? And why does that matter?

Here’s what you need to know.

The importance of examinations

The value of eye exams comes from how much they can tell your doctor about the health of your eyes. While there is a lot of overlap in both the Optomap and dilated fundus exam (DFE, or, dilated eye exam), there are some important differences as well.

What is a dilated fundus exam (DFE)?

As the name suggests, your eye must be dilated during this exam. To do this, a doctor will put in drops that will make your pupils widen, allowing more light in, and giving him or her a better view of the back of your eye. This is important because it enable your doctor to see blood vessels, which can give them important diagnostic information about certain health conditions such as stroke, heart disease, hypertension and diabetes.

Different instruments may be used to view the back of the eye. Most commonly, doctors use a fundus handheld lens and the slit lamp. Another popular technique is with a 20D handheld lens and a BIO – binocular indirect ophthalmoscope—that is worn on the doctor’s head.

Who needs a DFE?

This procedure is one of the best ways to spot disorders common to aging adults, like macular degeneration and glaucoma. DFEs can also help determine other conditions like retinal tears and detachment or ocular tumours.

Experts recommend that patients with diabetes, high muopes (nearsightedness) or those who may be more prone to glaucoma, undergo regular dilated retinal exams. People without the above listed conditions, or starting at age 65, should consider booking a DFE annually to maintain good eye health.

DFE: Features

  • Allows for higher magnification and higher resolution of images.
  • Gives a true 3D view of the eye, making it easier to spot more subtle changes in the retina.
  • It can also be conducted when the patient’s eye’s ability to focus is immobilized (called cycloplegia), which allows the doctor to better evaluate conditions like nearsightedness, farsightedness and astigmatism.

DFE: Considerations

  • Dilating the eyes can impact your vision for anywhere from 12 to 24 hours after the exam. You’ll be sensitive to light and could possibly experience some mild blurry vision until your pupils return to normal size.
  • Some patients (those who have very narrow anterior chamber angles) can’t undergo this procedure at all, because dilation could potentially cause a condition called angle closure glaucoma, where dangerous pressure builds up behind the eye. This risk is very low and the condition very rare.
  • The DFE also allows your ophthalmologist or optometrist to see only a very small part of the retina at a time (like looking at the inside of a large room from a keyhole in a door).

What is an Optomap exam?

This is an easy, comfortable eye exam where a patient stares into a small hole and a camera takes a detailed panoramic image of your eyes, one eye at a time. “Optomap” is the name of the imaging technology that captures the picture.

With these images, the doctor can easily read and manipulate the images for assessment. For example, doctors can use different filters to assess different layers of the fundus, to make measurements, or to compare with earlier images. This is extra helpful because small, subtle changes are easier to see when comparing images rather than when comparing written notes in a file.

Optomap: Features

  • Gives the examiner a wide view of your eye (like look through a doorway into a room, rather than through a keyhole).
  • No drops, or dilation required, which means no impact to your vision, and is safe for all patients.
  • Provides a lasting, accurate representation of the fundus (the inside of the eye).

Optomap: Considerations

  • To create a true 3D view of the eye like you would with a DFE, you must fuse together multiple images, making it a more in-depth process to get a 3D perspective.
  • Some subtle retinal findings show up better with a DFE than with Optomap.

How to know which exam is right for you

You can now understand how both the Dilated Fundus Exam (DFE) and Optomap have unique advantages when it comes to examining your eye for overall health and spotting certain conditions.

Fortunately, your eye care professional is an expert at knowing when to conduct which exam, and which is best for you. He or she will order one or the other (or both!) according to what symptoms you may be experiencing or when it’s time to check on different elements of your eye.

Remember to get your eyes checked regularly. And, if you’re ever wondering about which exam is appropriate for you – don’t be afraid to ask for more information. Your FYidoctors optometrist is here to help.

Contact FYidoctors today to book your next appointment.

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