Optical Coherence Tomography (OCT)

What is optical coherence tomography (OCT)?

Optical coherence tomography (OCT) is a noninvasive imaging method that eye care specialists use to produce cross-sectional images of your eye. It works by measuring wavelengths of infrared light that reflect off the back of your eye (your retina). OCT allows eye specialists to examine your eye in layers and to measure the depth of important structures. This helps them diagnose and treat eye conditions.

When used to examine your eye, optical coherence tomography is sometimes called ocular coherence tomography (ocular means eye-related). More recently, healthcare providers of other specialties have begun to use OCT to examine other tissues. OCT has provided a new way to look at blood vessels (angiography). Providers in cardiology, neurology and oncology have all found uses for OCT imaging.

When should I have an OCT eye test?

Your provider might suggest an optical coherence tomography if you have symptoms that suggest certain eye conditions, or if they see evidence of certain conditions during your eye exam. If you’re at risk of age-related eye problems or other eye diseases, your provider might suggest adding ocular coherence tomography to your regular schedule of eye exams. They can compare the scans over time to observe any changes.

What eye conditions can optical coherence tomography help diagnose and treat?

Eye care specialists often use OCT to examine your retina and the optic nerve in the back of your eye. This helps them diagnose retinal diseases and related conditions that may affect your vision, including:

• Bull’s eye maculopathy.
• Central serous retinopathy.
• Cystoid macular edema.
• Diabetes-related macular edema.
• Diabetes-related retinopathy.
• Eye cancer.
• Glaucoma.
• Macular degeneration.
• Optic atrophy.
• Posterior vitreous detachment.
• Retinal detachment.
• Retinal tears.
• Retinoschisis.

Sometimes, providers use OCT to look at the front of your eye, too. It can help them diagnose defects in the front of your eye or plan for eye surgery.

How does optical coherence tomography work?

Optical coherence tomography works similarly to ultrasound, another no-contact imaging method. Ultrasound (sonography) bounces inaudible sound waves off your tissues and measures the echo to create three-dimensional images. Similarly, OCT imaging bounces invisible red light off your tissues and measures them as they bounce back. This produces three-dimensional, cross-sectional images.

What happens during an OCT eye test?

An ocular coherence tomography scan takes just a few minutes in your provider’s office. You won’t need to prepare in advance. You might even have one directly after your standard eye exam.

Your provider might want to use eye drops to dilate your pupils before the exam. Then, you’ll sit in front of the scanner and rest your chin on a support attached to it. You’ll focus your eyes on a green target.

The OCT scanner will scan one eye at a time. You might see a red line while it’s scanning. You won’t feel anything, and nothing will touch your eyes. Try to stay still for the minute or two it takes to scan.

Are there any side effects or complications associated with OCT?

There aren’t any risks or side effects associated with an optical coherence tomography. But there are temporary side effects to having your pupils dilated. You’ll be sensitive to light and may have blurry vision for a few hours afterward. Some people get headaches. If you expect to have your pupils dilated, you might want to arrange for someone else to drive you home from the test, since your vision will take time to readjust.

What type of results do you get and what do the results mean?

Your eye care specialist will evaluate the images from your ocular coherence tomography scan. If they’ve taken previous scans, they’ll compare the images. They’ll discuss their findings with you as soon as they can. Their findings can confirm if you have a condition affecting your retina or optic nerve, and how advanced it is. Your provider will use this information to plan the next steps in your treatment.

When should I contact my healthcare provider?

It’s important to keep up with your regular eye exams so your provider can keep track of changes in your vision. If you notice any unusual symptoms or vision changes, be sure to let your provider know.

Call right away if you experience:

• New or persistent eye pain.
• Trouble seeing clearly or seeing colors.
• Frequent eye floaters or flashes.
• Sudden vision loss.