In this presentation from Glaucoma Subspecialty Day 2022, Dr. Donald Budenz discusses the use of optical coherence tomography (OCT) in diagnosing glaucoma progression. OCT is able to measure anatomic structures that change as part of the pathophysiologic process in glaucoma progression, including retinal nerve fiber, optic nerve, and ganglion cell layer parameters. Because OCT is able to measure these structures reproducibly, following these parameters over time offers clinicians the ability to diagnose glaucoma worsening; however, there are limitations. Dr. Budenz focuses on 3 areas of progression analysis: test reproducibility and the floor effect, Guided Progression Analysis software (Carl Zeiss Meditec), and TSNIT—temporal, superior, nasal, inferior, temporal—plots.