Optical coherence tomography (OCT) is a non- invasive imaging test. OCT uses light waves to take cross-section pictures of your retina. With OCT, your ophthalmologist can see each of the retina’s distinctive layers. This allows your ophthalmologist to map and measure their thickness. These measurements help with diagnosis. They also provide treatment guidance. Scanning takes about 5 – 10 minutes. If your eyes were dilated, they may be sensitive to light for several hours after the exam. If you have any questions about your eyes or your vision, speak with your ophthalmologist. He or she is committed to protecting your sight.