Optical coherence tomography (OCT) has become an important tool for diagnosing glaucoma and detecting glaucoma progression. Using a combination of didactic lecture and case examples, this video presents the interpretation of OCT for glaucoma diagnosis and progression, primarily relying on the Cirrus (Zeiss) OCT platform. Some examples of glaucoma detection and progression with Spectralis (Heidelberg) and RTVue (Optovue) are also presented. Case examples of false positives (“red disease”), false negatives (“green disease”), and other diagnostic dilemmas are reviewed to help the viewer sort the real from the artifact in OCT interpretation for glaucoma.