Optical coherence tomography

Optical coherence tomography (OCT) is a painless imaging test that takes detailed pictures of the back of the eye. The test works like an ultrasound, but instead of sound waves, it uses invisible infrared light to see inside the eye. This safe technology provides a clear view of the structure and thickness of the retina and the optic nerve. By examining these layers, your provider can find early signs of disease or track small changes over time.

At Penn Medicine, specialists use advanced neurodiagnostics and imaging tools like OCT to evaluate both eye and nerve health. Our ophthalmology and neuro-ophthalmology programs work closely together to diagnose and monitor conditions that affect vision. With deep experience and leading technology, we focus on giving you clear answers and a care plan that fits your needs.

OCT may be recommended if you have vision changes, are at risk for certain eye diseases, or need monitoring for an existing condition. It’s often part of a routine eye exam when there is concern about the retina or optic nerve. Because OCT scans can track tiny changes over time, it’s a helpful tool for diagnosing and monitoring conditions like:

• Age-related macular degeneration (AMD)
• Glaucoma
• Diabetes-related eye disease, like diabetic retinopathy
• A macular hole or pucker
• Swelling in the retina
• Ocular (eye) cancer
• Blockages in the blood vessels
• Retinal detachment or tears

An OCT eye test is usually done during a regular eye visit and takes only a few minutes. You’ll sit in front of the machine and rest your chin on a support to help keep your head still. Without touching your eye, the camera scans one eye at a time. You’ll focus on a green target and try to remain still during the test.

In some cases, eye drops are used to dilate your pupils so the retina can be seen more clearly. If your eyes are dilated, you may have temporary blurred vision or light sensitivity for a few hours afterward.

After the scan, your eye care specialist will review the images. If you’ve had previous scans, the new images are compared with earlier ones to look for changes. A normal result shows healthy retinal layers with the right thickness and no unusual fluid or swelling.

If changes are found, the images can help confirm a diagnosis, show how advanced a condition may be, and guide treatment decisions. OCT is especially helpful in detecting early stage disease, often before symptoms become severe. Your care team will explain the findings and talk with you about any next steps, so you know what to expect moving forward.