Optical Coherence Tomography Progression Analysis: Sample Cases
The ability to detect glaucoma progression in a timely manner is crucial for adequate monitoring of the disease. Structural progression commonly precedes functional progression in glaucoma. Optical Coherence Tomography (OCT) is the current gold standard for detecting early structural progression in glaucoma. Spectral domain OCT systems can assess changes in the peripapillary retinal nerve fiber layer (RNFL), macular ganglion cells and their neural processes and optic nerve head simultaneously with high reliability. Commercially available OCT progression software of Cirrus HD-OCT is able to perform both event and trend analysis for all the above structural parameters. Spectralis OCT on the other hand mainly uses trend analysis. In order to fully benefit from these features of the OCT progression analysis, the clinician needs to be familiar with the basics of the analysis software and to understand the shortcomings of the current systems. This chapter presents examples of structural progression on OCT imaging in patients with early, moderate and advanced glaucoma. Progression analyses are provided for peripapillary RNFL, macular ganglion cells, and visual fields in order to familiarize the reader with the OCT progression analysis with a step-by-step approach. Although this chapter is based on Cirrus HD-OCT and Spectralis OCT progression analysis software, it can be helpful to the users of other OCT systems as all the OCT systems use at least one or more methods presented in these sample cases.