Optical coherence tomography (OCT) is a non-invasive imaging test that uses light waves to take cross-section pictures of your retina. 

Your retina is 10 different layers and with OCT, your optometrist can see each of the retina’s distinctive layers to see fine and sometimes subtle abnormalities. This allows your optometrist to map and measure their thickness and changes over time. These measurements help with diagnosis and can also guide treatment for glaucoma and retinal diseases, like age-related macular degeneration (AMD) and diabetic eye disease.